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PASCAL·SO USER`S GUIDE

1. Pate Dulle PASCAL 80 USER S GUIDE Manual Order Number 9801015 02 Intel Corporation has carefully reviewed this Vendor Supplied Product for its suitability and operational characteristics when used with intel products and believes that the product will operate and perform according to its published user manuals HOWEVER INTEL MAKES NO WARRANTIES WITH RESPECT TO THE OPERATION AND USE OF THIS VENDOR SUPPLIED PRODUCT Successful use depends solely on customer s ability to install and use this product This Vendor Supplied Product is licensed on an as is basis and Intel Corporation does not guarantee any future enhancements or extensions to this product The existence of this product does not imply its adaptation in any form as an Intel standard nor its compatibility with any other Intel product except as specifically stated in the published user manuals Intel wil provide limited telephone assistance to the customer in the understanding of the operation of the product In addition if a problem is encountered which the user diagnosis indicates is caused by a defect in this Vendor Supplied Product the user is requested to fill out a Problem Report form and mai it to Intel Corporation MCSD Marketing 3065 Bowers Avenue Santa Clara CA 95051 Intel will use its best efforts to respond to Problem Reports in one of the following ways 1 Release information to correct the problem 2 Offer a new revision when available w
2. unsigned integer gt sign unsigned integer sign lt string gt character character unsigned constant unsigned number lt string gt constant identifier NIL letter A BiciDIiElFIGIBIIIJIKILIMINIOIPIOIRISITIUIVIWIXIYIZI alblcidiel ligihliiljlkll1 miniolpigirisitiuiviwixiylz digit 0 1 21314 151 61718191 0 APPENDIX H SUMMARY OF EXTENSIONS TO STANDARD PASCAL PASCAL 80 is an extension of Standard Pascal as defined in the PASCAL User Manual and incorporates structures and operations not found in Standard Pascal The following data types are extensions to Standard Pascal and are described in Chapter 2 and Chapter 7 The string type Untyped FILES INTERACTIVE files The MESSAGE type The following predeclared procedures and functions are extensions to Standard Pascal and are described in Chapter 3 blockread f a b s integer blockwrite f a b s integer bufferread f a b integer bufferwrite f a i b integer close f PURGE concat s s string copy s i l string delete s i l errorset p exit p fillchar a l c gotoxy x y insert s t i ioresult integer length s integer log x real mark p memavail integer moveleft s d 1 moveright s d portinput p v portoutput p v pos p s integer pwroften x real release p reset f lt string gt rewrite f lt string
3. PASCAL 80 Language Features o PROCEDUREs and FUNCTIONs As in Standard Pascal PASCAL 80 allows for associating an identifier with a pro gram part and hence defining named PROCEDUREs and FUNCTIONs The syntax for these declarations is the same as in Standard Pascal except in one respect In PASCAL 80 procedures and functions may not be used as arguments to other procedures or functions SEGMENT Procedures In order to allow for the execution of very large programs which cannot fit into main 4 memory PASCAL 80 allows these programs to be partitioned into SEGMENT PROCEDUREs or SEGMENT FUNCTIONS This language construct allows for dynamic overlaying in that a SEGMENT PROCEDURE FUNCTION is resident in memory only when it is a part of the dynamic execution thread Once a SEG MENT PROCEDURE FUNCTION exits the portion of memory which it occupied is now free for some other overlay A SEGMENT is declared as follows SEGMENT PROCEDURE initialize firsttime boolean and SEGMENT FUNCTION getcharacter char raava where denotes the body of the PROCEDURE FUNCTION which has the same syntax as non overlay program parts The main body of programi is always resident as is every procedure which is not a SEGMENT All SEGMENT declarations must occur before any of the resident procedure declarations or the main body of the program 2 7 As in all implementations of the Pascal programming lan
4. label lt unlabelled statement lt unlabelled statement simple statement structured statement simple statement assignment statement procedure statement lt go to statement empty statement assignment statement variable expression function identifier expression variable entire variable component variable lt referenced variable X entire variable variable identifier variable identifier identifier component variable indexed variable lt field designator gt file buffer indexed variable array variable expression expression array variable variable lt field designator gt record variable lt field identifier record variable variable lt field identifier identifier file buffer file variable file variable variable referenced variable pointer variable lt pointer variable variable expression lt simple expression simple expression relational operator simple expression relational operator lt gt lt lt gt gt IN simple expression term sign term simple expression gt lt adding operator gt lt term gt adding operator OR term factor term m
5. 2c ce eee ee ee eee 3 7 String Manipulation Routines 2 3 9 Character Array Manipulation Routines 3 10 CHAPTER 4 OPERATING INSTRUCTIONS Getting Started with PASCAL 80 4 Release DISKS sia iris 4 1 Nita Steps caida edi 4 1 Compiler uc er aa 4 2 Rune Time System wunderbarer 4 2 Librames 5 0002 25542 rare 4 2 Example Programs isaac re E ERES 4 2 CONTENTS PAGE ligure Programs sica bai e x a ce esce edo dca 4 2 Run Time System Memory Layout 4 2 Operating the PASCAL 80 System 4 3 Invoking PASCAL 80 eeees 4 3 Command Line Syntax for PASCAL 80 4 4 Code Filename Specification 4 4 Command Line Options L 4 5 Program Tracing Facility 4 5 The TRACE Flap ipsa vet idu or eek d RA 4 5 Tracing Instructions o oooooomoooom oo 4 5 Run Time Monitoring eere 4 6 Displaying the Statistics oo ooooooooo o 4 6 Automatic Program Execution ooooooo 4 1 Interrupting Program Execution 4 7 Operating the PASCAL 80 Compiler 4 7 Command Line Syntax for the Compiler 4 7 Compiler DIIGCUVES ease cade EN RR ODER eR 4 8 Compiler Command Line Directives 4 8 Excluded Combinations 4 9 Summary of Information on CRT 4 9 Compiler Listing Format o ooooooo oo o
6. CHAPTER 5 EXAMPLE PROGRAMS The Pascal programs presented in this chapter are designed to illustrate both the basic characteristics and some of the language extensions in PASCAL 80 Compiling the Example Programs Compile all the demonstration programs on the release diskette These programs have the extension PAS For example PASCAL PASCAL 80 Vv r gt COMP EX PAS PASCAL 80 Compiler Vv r COMPILING EX PAS Symbol table space remaining 12234 bytes 37 lines compiled PASCAL 80 Vv r gt NOTE All of the examples in this manual assume that a PASCAL 80 system diskette is created by following the initial steps in Chapter 4 and that this Pascal software diskette is loaded in drive 0 If the diskette was loaded in drive 1 the first line in the above example would be F1 PASCAL the third line would be F1 COMP F1 EX PAS and the other examples in this manual would be modified accordingly To return to ISIS II type QUIT For example PASCAL 80 Vv r 2QUIT 5 1 Example Programs PASCAL 80 A directory listing of the disk will show that two new files exist namely EX LST which is the list file and EX COD which contains the intermediate code Now com pile the programs BUFFER PAS SEEKEX PAS and ERROR PAS Note that ERROR PAS has a bug in it which is present to show error formats and is for demonstration purposes only It does not affect the running of the program The message produced by the error is
7. 4 10 Initial Compilations y Ra rn 4 10 CHAPTER 5 EXAMPLE PROGRAMS Compiling the Example Programs 5 1 Running the Demonstration Programs 5 2 Addition and Subtraction of Numbers 5 2 EX PAS Program Listing uam AREE PRI 5 3 Bufferread and Bufferwrite Example 5 4 BUFFER PAS Program Listing 5 4 ERROR PAS Program Listing 5 5 Example of Seek and Advanced Record Structure 5 6 Information Retrieval Program SEEKEX PAS 5 6 SEEKEX PAS Program Listing 5 7 CHAPTER 6 SEPARATE COMPILATION PROGRAM LINKAGE RELOCATION AND EXECUTION Partitioning a Pascal Program 6 1 The Structure of a Partitioned Program 6 1 Code File Construction oooooooooooomono 6 3 Linking with non Pascal Modules 6 4 PASCAL 80 Extensions such 6 4 Invoking an External Procedure or Function 6 8 The External Reference Table 6 8 Program Execution with External Objects 6 9 Compile the Pascal Program 6 9 Compile and or Assemble the External Module s 6 9 Link the Modules Together 6 10 2 2 2 2 27 R 9 9 9 9 9 9 CONTENTS Cont d PAGE Locate the External Module 6 10 Load the External Module into Memory and Invoke the PASCAL 80 Run Time System 6 11 Load and Go Program Generation 6 12 Ge
8. ERROR sum cause an error Line 15 Procedure ADD Error 104 The arrow A points to the location in the line where the error occurred Running the Demonstration Programs When these programs have been compiled and run you have checked out your disk and have mastered the fundamentals of the PASCAL 80 facilities Addition and Subtraction of Numbers PASCAL PASCAL 80 Vv r gt EX NOTE If you have not returned to ISIS II i e QUIT then you type only gt EX since you are already in the PASCAL 80 System Also note that the code file produced by compiling EX PAS is EX COD but to run EX COD only EX need be typed since the PASCAL 80 System automatically appends COD to any name typed in Exceptions to this condition are explained in Chapter 4 under Code Filename Specification The program is now running Input two integers 2 5 The difference of the two is 3 The sum of the two is 7 PASCAL 80 V vr gt PASCAL 80 Example Programs EX PAS Program Listing Line Seg Proc Lev Disp Qo SOG WN CO CO CO CO CO CO CO CO AD AD AD A PD AS BD DB ho ROB A A m ml mo Ont OD oo m yO con OF PO Wn ON PWM DD b b ASS ee ee ee E SS ee ee ee ee ee ee ee h b b o C9 C9 CO CO CO CO Aa d d d d CO C9 OD RD DD RD DA a OO O O NUUNA 2220002220000 oo oo Mm ho w MN N aAa Aa
9. PASCAL 80 PASCAL 80 Separate Compilation Program Linkage Relocation and Execution A 64K Intellec System has a highest usable memory address of F6COH Therefore the base of the external module should be located at F6COH total length of module For example if the length of the external module is 4096 1000H bytes the base of the module must be set to E6COH or lower in the LOCATE step As was mentioned above the external reference table must be situated at the begin ning of the external module If the linking operation described in the previous sec tion was performed correctly the external reference table will be situated at the beginning of the CODE segment in the relocatable object file of the external module Therefore if the CODE segment is the first segment in the executable object file generated by LOCATE the external reference table will be positioned correctly The ISIS II LOCATE utility will position the CODE segment as the first segment if the ORDER control is not used in the LOCATE command or if it is used CODE is mentioned ahead of any other segment name Use of the LOCATE facility is fully described in the S S II User s Guide For example LOCATE EXTMOD OBJ CODE 0E6COH locates the CODE segment of the module and therefore the entire module at E6C0H and writes the absolute object module onto EXTMOD Unless a private STACK is required the STACKSIZE 0 control should be specified
10. PASCAL 80 Separate Compilation Program Linkage Relocation and Execution e Ifa procedure or function is called recursively each of its instances has its own e data frame allocated on the STACK e All parameters to procedures functions and operators are passed on the STACK e The code of an active SEGMENT PROCEDURE or FUNCTION is allocated on the STACK e All dynamic variables are allocated on the HEAP by the new v predeclared procedure A consideration of these factors leads to the following conclusions e The longer a procedure call chain is the more STACK space is used e The deeper the level of recursion of a procedure or function the more STACK space is used e Two procedures which are never active concurrently will not extend the STACK concurrently e The more complex a Pascal expression is the more STACK space is used during e its evaluation Linking the Object Module The relocatable object module created from the pascal program code file must now be linked to the Pascal Run Time libraries and associated external modules if any The required LINK command has the form LINK lt input list gt TO lt link file gt lt link controls gt The lt input list gt is a list of ISIS II files of the form lt program module gt 4 lt external ref table gt lt external module gt amp P80RUN LIB P80RAR LIB P80ISS LIB where e lt program module gt is the relocatable object file created from the
11. case list element END case list element case label list statement empty case label list case label case label repetitive statement while statement repeat statement for statement while statement WHILE expression DO statement repeat statement REPEAT statement statement UNTIL expression lt for statement FOR control variable for list DO Statement lt for list initial value TO final value initial value DOWNTO final value control variable identifier initial value expression final value expression with statement WITH record variable list DO statement record variable list record variable record variable lt identifier gt letter letter or digit gt lt letter or digit letter digit constant unsigned number sign unsigned number constant identifier sign constant identifier lt string gt lt unsigned number gt lt unsigned integer gt lt unsigned real gt lt unsigned integer gt lt digit gt lt digit gt lt unsigned real gt lt unsigned integer gt lt digit gt lt digit gt lt unsigned integer digit digit E scale factor unsigned integer E scale factor scale factor
12. from which both the HEAP and the Execution STACK are allocated The HEAP grows upward from the bottom of the free space while the STACK grows downward from the top The amount of free space a Pascal program needs is dependent on both the static and dynamic characteristics of the program For example the size of the local data frame of a procedure will affect the STACK space used as will the calling depth of a set of recursive procedures In order to assist in the determination of the amount of free space a Pascal program requires the PASCAL 80 Run Time System has the SIZEON command This feature described in detail in Chapter 4 causes the Run Time System to continuously monitor the amount of free space used by a program and to keep track of the maximum value This value can then be displayed with the STATS command Remember however that the value obtained during one execu tion run might not be valid during another run if the program has different execu tion characteristics In addition to monitoring the sizes of the STACK and HEAP during one or more execution runs the following factors should be considered when computing the required free space size The global data frame is allocated on the STACK when the program begins execution e The data frame of a procedure or function is allocated on the STACK only when that procedure or function is active i e only when it is part of the dynamic calling chain PASCAL 80
13. widowed date married date divorced date divorced date first divorce boolean single independent boolean end person var people file of person ch char recnumber integer procedure initfile only one boolean var i integer ch char procedure get date var date to set date begin with date to set do begin repeat readln i case i of 1 month jan 2 month feb 3 month mar 4 month apr 5 month may 6 month jun 7 month jul 8 month aug 9 month sep 10 month oct ll month nov 12 month dec end case if i lt 1 or i gt 12 then write Bad date Try again until i in 1 12 write DAY repeat readln i if i lt 1 or i 31 then write Bad date Try again until i in 1 31 day ij write YEAR readln year end with end get date begin finit files l if not only one then rewrite people people dat else seek people recnumber repeat with people do begin writeln write First name readln input name first if not eof input then hd begin write Last name readln input name last write S S number readln input ssnum repeat write M ale or F emale readln input ch case ch of M m x sex male F f sex female end Example Programs SEEKEX PAS Program Listing Cont d until ch in M m EF f writeln write Input b
14. C Un i CJ ND A O Hn Figure 3 1 Examples of Predeclared Procedures reset rewrite get put and close This procedure may be used only on TEXT or INTERACTIVE files 1f f is omitted input is assumed Note that this construct is equivalent to read f v1 read f vj If vi is of type string read f vi will read up to the end of the line and set eoln f true See figure 3 3 for an example readin f v1 vj This construct is equivalent to the sequence read f v1 vj readin f where readIn f is used to read to and subsequently skip past the end of the current line If the file is not exhausted eof f and eoln f are set false See figure 3 3 for an example PASCAL 80 Predeclared Procedures f This program uses the data file created in program threel to illustrate the use of the predeclared procedures reset seek and get program three2 var 1 integer datafile file of integer begin 3 2 reset datafile F1 DDATA DAT for i 10 downto 6 do begin seek datafile i get datafile open the file DDATA DAT on drive 1l Seek to a record get its value write output Record number i 3 and display the data write output Record value datafile 3 writeln output end close datafile end 3 2 Executing this program will result in the following output Record number 10 Record value 10 Record number 9 Record value 9 Record
15. Cee Ce AAA A A A ee ee en ey ho o o EE AAA AA AAA A A O ey O C9 hb bh d d Bh WF N N MM KH d o 4 3 3 3 3 44 64 65 67 108 0 0 27 68 87 109 109 116 132 179 197 208 208 226 262 292 331 378 378 388 program example Example using bufferread and bufferwrite with break characters var buffer string disk storage file break char new__len len integer buff array packed array 0 80 of char begin rewrite disk storage data writeln Input a line of text readin buffer len bufferwrite disk storage buffer 1 length buffer repeat reset disk storage writeln writeln write Input break char cntrl Z to stop readin break if not eof input then begin new len bufferread disk storage buff array len ord break writeln The buffer read writeln copy buffer 1 abs new len writeln Length abs new len 0 if new len lt 0 then writeln Break char not found end until eof input end T PASCAL 80 Example Programs ERROR PAS Program Listing Line 00 N Oo Qn bh coh de 10 11 12 13 14 15 16 ERROR 104 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 Seg m b bh ee ee ee ee ee ee Se a Sa aa L A E He mo o m do e dk MR eo dl A A h h mb hb h bh Proc Bo d BW W CO PMY NN A
16. If the R is followed by a range checking code is generated by the compiler such that if a value range error occurs while running the program a run time error occurs When followed by a no range checking code is generated if a value range error does occur while running the program a run time error does not occur The default valueis R O This directive determines whether the compiler operates in overlay mode If the O directive is given the compiler operates in overlay mode If the O directive is given the compiler doesn t operate in overlay mode In the O mode there are about 6300 bytes less memory available for symbol table space but compile time is decreased since the compiler does not have to read from the disk as often as in the O mode O is therefore very useful for compiling small and moderate sized programs O is the default value T This directive determines whether the compiler generates tracing instructions and may appear anywhere in the source code If the T directive is given tracing instructions are inserted in the generated object code If the T directive is given no tracing instructions are generated The default value is T H This directive specifies a heading to be printed on the second line of each page of the compiler listing just below the main title line All characters in the directive following the H become part of the heading For example H File Translation Program will c
17. LST CODE external file name Specifies the file to which the code is to be directed The default is lt source filename gt COD NOECHO Error lines are echoed on the console unless this directive is specifed GLOBAL external file name Specifies the global symbol table file when separately compiling a partitioned Pascal program The default is lt source filename gt SYM WORKFILE lt device gt Specifies which diskette device is to be used for the compiler s workfile P8OWRK TMP The default value is the device of the output code file DATE lt date gt Specifies the date to be included in the page heading of the compiler listing The lt date gt parameter is any sequence of nine or fewer characters not contain ing parentheses The default value is all spaces NOSTATISTICS Specifies that the compiler should not accumulate or list the procedure data frame and parameter sizes ETAB external file name Specifies the external table file when compiling a Pascal program with external references The default is lt source filename gt ERT C 1 Summary of Compiler Directives PASCAL 80 C 2 Excluded Combinations Certain of these directives may not be used in combinations The following table shows which directives are excluded if the directive in the left hand column is specified NOLIST Exciuded Directives LIST ERRLIST NOCODE CODE Embedded Directives Embedded compiler directives are ins
18. Release Disk in source form PASCAL 80 programs may be loaded and executed under control of the PASCAL 80 Command Line Interpreter as described in Chapter 4 or they may be converted to standard ISIS II object modules and executed directly in the ISIS II environment The procedure for generating these Load and Go versions is described in Chapter 6 Also described in Chapter 6 are the PASCAL 80 extensions which allow a Pascal program to link with non Pascal object modules coded in PL M 80 FORTRAN 80 or ASM 80 Chapter 7 describes the procedures necessary to generate an RMX 80 applications system which includes a Pascal task The RMX 80 Interactive Configuration Util ity which automates much of this process is also discussed A powerful feature of the PASCAL 80 System is the ability for a Pascal program to declare an error procedure which is invoked upon the detection of a run time error Use of this facility which is described in Chapter 8 is extremely important in appli cations systems since it allows a program to retain control over its execution even in the event of run time errors 1 1 Introduction 1 2 The PASCAL 80 Language The PASCAL 80 language is a superset of the programming language Pascal as defined in PASCAL User Manual and Report Second Edition by Kathleen Jensen and Niklaus Wirth Springer Verlag 1974 Corrected Printing 1978 This book defines Standard Pascal and will be referred to in the r
19. Table F 1 Nonfatal Error Numbers Returned by System Calls OPEN READ WRITE SEEK RESCAN CLOSE DELETE RENAME ATTRIB CONSOL WHOCON ERROR LOAD EXIT SPATH 3 4 5 9 12 13 14 22 23 25 28 2 8 2 6 2 19 20 27 31 35 2 21 2 4 5 13 14 17 23 28 32 4 5 10 11 13 17 23 28 4 5 13 23 26 28 None all errors are fatal None None 3 4 5 12 13 22 23 28 34 None 4 5 23 28 Table F 2 Fatal Errors Issued by System Calls OPEN READ WRITE SEEK RESCAN CLOSE DELETE RENAME ATTRIB CONSOL WHOCON ERROR LOAD SPATH 1 7 24 30 33 24 30 33 7 24 30 33 7 24 30 33 33 33 1 24 30 33 1 24 30 33 1 24 30 33 1 4 5 12 13 14 22 23 24 28 30 33 33 33 1 15 16 24 30 33 33 APPENDIX G SYNTAX SUMMARY o MM M ee The syntax of Pascal is described below using Backus Naur Form BNF notation This notation uses meta symbols which belong to the BNF formalism and are not symbols of the Pascal language These meta symbols are m 9 In addition syntactic constructs are denoted by English words enclosed in angular brackets as in lt digit gt These words s also define the meaning or nature of the con struct The syntactic construct lt empty gt denotes the null sequence of symbols The first symbol is used in BNF productions to mean is defined to be as in
20. Y ODOOO O OO 090090909 9 4 gy m mn oO OO m cc 100 108 108 116 175 227 235 program example var i j integer function sub valuel value2 integer integer begin Sub value1 value2 end sub procedure diff and sum var sum difference integer var temp integer function add value1 value2 integer integer begin add valuel value2 end add begin diff and sum temp add sum difference difference sub sum difference sum temp end diff and sum begin example writeln writeln writeln write Input two integers readin i j if i 20 or j lt gt 0 then begin diff and sum i j writeln end writeln writeln The difference of the two is j 0 writein The sum of the two is i 0 writeln end example 5 3 Example Programs 5 4 PASCAL 80 Bufferread and Bufferwrite Example gt BUFFER Input a line of text THIS IS A LINE OF TEXT Input break char cntrl Z to stop A The buffer read THIS IS A Length 9 Input break char cntrl Z to stopl W The buffer read THIS ISALINE OF TEXT Length 23 Break char not found Input break char cntrl Z to stop cntrl Z gt PASCAL 80 Vv r gt QUIT BUFFER PAS Program Listing Line Seg Proc Lev Disp On Dm Aa QN GW A AD AD AD AD AD AD ADO AO PR dd Ss ol oS c c oo OD 05 on bw OW On DM ana GON Oo D pen o ho o o o Crees Crees Cre o o
21. a a 2 2 09 09 C C0 C2 CO Il hh d m Lev OOO CO a Ad Q5 ADO ao ODO a a 24 O DO Oo gt Disp Ooo ow 120 0 co Oo WHA WW O gt 22 10 20 23 36 26 97 85 94 94 100 108 108 116 175 227 235 program example vari j integer function sub value1 value2 integer integer begin sub value1 value2 end sub procedure diff and sum var sum difference integer var temp integer function add value value2 integer integer begin ERROR sum cause an error add value value2 end add begin diff and sum temp add sum difference difference sub sum difference sum temp end diff and sum begin example writeln writeln writeln write Input two integers readin i j if i lt gt 0 or lt gt 0 then begin diff and sum i j writeln end writeln writeln The difference of the two is j 0 writeln The sum of the two is 1 0 writeln end example 5 5 Example Programs PASCAL 80 Example of Seek and Advanced Record Structure This program is an information retrieval program named SEEKEX PAS which is designed to manage user information records in a data file named PEOPLE DAT Each record in this file contains the name of a person along with additional personal information SEEKEX will display a requested record and will allow the user to
22. a program is shown in figure 6 3 This Pascal program references two external modules ASUM and PSUM each of which declare both an integer variable and an integer function with three parameters of type range The module ASUM is written in 8080 8085 Assembly Language and the module PSUM Is written in PL M 80 Each of the external functions merely computes the sum of their three parameters stores the sum in a PUBLIC variable and then returns the result as their function value As is shown in this example the module coded in PL M must not be a main module i e it must not contain executable statements at the module level Note that there may be multiple public declaration records but that they must all appear before any private objects are declared In particular this restriction causes all external objects to be in the global environment of the Pascal program Therefore as for all global identifiers every external variable procedure and func tion name must be different from every other external name and from every private global variable name If this condition is not satisfied e g if two external names are the same or if an external name is the same as a private global name the com piler will generate Error 101 Identifier declared twice and will not accept the duplicate name However it is possible that two separate public declaration records may contain declarations for variables of the same type If this type is not a prede
23. a string which is the concatenation of the strings s1 to sj There is no restriction on the number j except that the resultant string be less than 256 characters See figure 3 7 for an example copy s lt index gt lt length gt string Returns substring of s starting at position index of length characters See figure 3 7 foran are insert s1 s2 lt index gt Inserts the string s into the string s2 starting at the lt index gt th character in s2 See figure 3 7 for an example 3 9 Predeclared Procedures PASCAL 80 This program illustrates the use of the string manipulation routines length pos concat copy insert and delete program three var sa Sb sc sd string 70 First STRING to be defined Sb Second STRING we are defining sc in this example sd null string writeln length sa 3 length sd 3 writeln pos nd sb 3 pos XXX sc 3 writeln concat sb sc writeln copy sa 7 3 insert Pascal sb 8 writeln sb delete sa 14 6 writeln sa end 3 7 Executing this program results in the following output 26 0 5 0 Second STRINC we are defining in this example STR Second Pascal STRING we are defining First STRING defined Figure 3 7 Examples of String Manipulation Routines length pos concat copy insert and delete Character Array Manipulation Routines These routines operate on PACKED ARRAY OF char structures N
24. control to the PASCAL 80 System When the compilation is complete the compiler displays the message Symbol table space remaining nnnnn bytes mmmmm lines compiled where nnnnn is the number of bytes of memory that were not used during compila tion of the program This tells you how much more symbol table space your program can use The mmmmm is the number of lines in the program Compiler Listing Format The general layout of the list file is as follows PASCAL 80 Compiler Vv r filename date page nnn Line Seg Proc Lev Disp nnnn nn nnn n nnnn statement 1 nnnn nn nnn n nnnn statementn The first two lines are title information and are repeated for each page Line is the line number Seg is the segment number Proc is the procedure number Lev is the current level of nesting and Disp is the displacement of the variable or statement in the current procedure These numbers are useful in debugging since when a run time error occurs the segment number procedure number and instruction displace ment are displayed See Appendix E Run Time Errors for more information Refer to Chapter 5 for examples of program listing Initial Compilations When developing a PASCAL 80 program it is often desired to perform a quick syntax and semantic check of the program Compiling a program with NOSTATISTICS NOLIST and NOCODE specified on the command line will per form these checks in the minimum possible time
25. digit 011 2131415161718 9 o The bar symbol is used to denote alternation as in the above production In other words digit is defined to be either 0 1 2 or 9 The braces and denote zero or more repetitions of the symbols enclosed in them In particular the production Xu y is a short form of the recursive construct X empty XY In the following productions symbols in upper case denote terminal symbols not syntactic constructs The BNF Description of Pascal lt program declaration program heading block program heading PROGRAM identifier PROGRAM identifier file identifier file identifier file identifier identifier block label declaration part constant definition part type definition part variable declaration part lt procedure and function declaration part statement part lt label declaration part empty LABEL label label label unsigned integer constant definition part gt empty CONST constant definition gt constant definition constant definition identifier constant lt constant identifier identifier type definition part empty TYPE type definition type definition lt type definition identifier type lt type gt simple type struct
26. identify Intel products BXP intellec Multibus CREDIT iSBC Multimodule i SBX PROMPT ICE Library Manager Promware CS MCS RMX Insite Megachassis UPI Intel Micromap Scope Intelevision and the combination of ICE iCS iSBC iSBX MCS or RMX and a numerical suffix A235 780 5K FL This manual describes the PASCAL 80 language for programming the 8080 and 8085 microcomputers PASCAL 80 is based on the Pascal language invented in 1970 by Professor Niklaus Wirth of Zurich and incorporates extensions designed to take advantage of both the microcomputer features of the 8080 and 8085 and the system features of ISIS II Each release of PASCAL 80 1s characterized by a two digit code in the form of version number release number within version Manual Organization The PASCAL 80 language is a superset of the Pascal programming language as defined in PASCAL User Manual and Report Second Edition by Kathleen Jensen and Niklaus Wirth Springer Verlag 1974 Corrected Printing 1978 This book defines Standard Pascal and will be referred to in the remainder of this manual as PASCAL User Manual Since PASCAL User Manual is a concise reference for the features of Standard Pascal the programming language PASCAL 80 will be described only by its differences from and extensions to Standard Pascal the assumption being that the reader is familiar with the contents of PASCAL User Manual and
27. load and go version of your Pascal program which is directly executable from the ISIS II command line interpreter All of Chapter 6 exceeds standard Pascal Partitioning a Pascal Program In order to allow for easier development of large PASCAL 80 programs a program may be partitioned into separate COMPONENTS or compilation units These e COMPONENTS are then compiled separately and combined by the JOIN utility to produce the final code file since the COMPONENTS are compiled separately a change in a COMPONENT requires that only that COMPONENT be recompiled not the entire program This recompilation is then followed by the JOIN procedure The entire program must be recompiled only if the global data in the main program is altered The Structure of a Partitioned Program A partitioned program set consists of a main PARTITIONED program and one or more separate COMPONENTS The main PARTITIONED program contains the global data and the outer block program statements as well as all resident global procedures Each COMPONENT contains one or more global segment procedures Each one of the COMPONENTS as well as the main PARTITIONED program is a compilation unit and is compiled separately Each global segment procedure which is contained in a COMPONENT must be declared in the main program as a SEPARATE segment procedure as follows Segment procedure pl separate Note that the syntax of a SEPARATE segment procedure declaration is simil
28. main PARTITIONED PROGRAM and each of the COM PONENTs are compiled separately The PARTITIONED PROGRAM must be compiled before any of the COMPONENTS can be compiled During the compilation of the PARTITIONED PROGRAM the compiler writes the global symbol table onto a diskette file This global symbol table file is then read in during the compilation of each of the COMPONENTS In this way each of the SEPARATE PROCEDUREs and FUNCTIONS of a partitioned program set is declared within the global environment declared in the main PARTITIONED PRO GRAM The GLOBAL lt file name gt compiler directive allows the name of the global symbol table file to be specified In the absence of this directive the compiler uses the file name source file name SYM 6 3 Separate Compilation Program Linkage Relocation and Execution PASCAL 80 For example if SIX1 PAM is a PARTITIONED PROGRAM the command COMP SIX1 PAM GLOBAL MYSYM XYZ will cause the global symbol table to be written onto MYSYM XYZ while the com mand COMP SIX1 PAM will cause the global symbol table to be placed on the file SIX1 SYM After all of the compilation units of a partitioned program set have been successfully compiled the JOIN utility is used to combine all of the separate code files into a final executable code file The format of the JOIN command is JOIN code file lt code file gt TO lt code file gt For example the following command will com
29. moderately conversant with Standard Pascal Chapters 1 through 3 describe the features of the PASCAL 80 language and Chapter 4 describes how to operate the PASCAL 80 System Chapter 5 presents example programs illustrating the features of PASCAL 80 The appendices supply reference information for all aspects of program generation compilation and execution Audience This manual is intended for programmers who are familiar with PASCAL It con tains the following chapters and appendices Chapter 1 Introduction system which gives a general description of the PASCA L 80 Chapter 2 Language Features which describes the data types control con structs and procedure and function declarations Chapter 3 Predeclared Procedures which describes the predeclared procedures and functions in PASCAL 80 Chapter 4 Operating Instructions which describes how to generate compile and execute a PASCAL 80 program Chapter 5 Example Programs which presents four PASCAL 80 programs complete with compiler listing and output Chapter 6 Separate Compilation Program Linkage Relocation and Execution which gives general instructions for partitioning a Pascal program into separate compilation units for linking to external non Pascal object modules and for creating Load and Go versions of Pascal programs PREFACE ii Chapter 7 Preparing Programs to Run Under RMX 80 which gives information applic
30. particular these conditions imply that a data item which is equal in size to one of type integer two bytes will always be allocated on a word boundary However the RMX 80 Message Format is incompatible with these conditions in that the HOME EXCHANGE field and the RESPONSE EXCHANGE field as well as any additional data items in the remainder of the message are aligned on odd byte boundaries It is therefore not possible to define a data type in PASCAL 80 which has the same structure as an RMX 80 message Consequently in the absence of any specific language extensions an RMX 80 message would be a cumbersome type to manipulate The above incompatibility is resolved by the definition of a new class of data types and a set of additional predeclared procedures and functions in the supporting environment The MESSAGE Data Type RMX 80 PASCAL incorporates the MESSAGE type which is used to define a class of structured data types corresponding to RMX 80 messages Each Pascal MESSAGE is one byte longer than its associated RMX 80 message This additional byte 1s located at the beginning of the Pascal defined MESSAGE and offsets the fields in the RMX 80 message format by one byte The result of the inclusion of this extra byte is that from the viewpoint of Pascal the HOME EXCHANGE field the RESPONSE EXCHANGE field and all succeeding fields are located on word boundaries and therefore are simple to define and manipulate in a Pascal program For ex
31. program module gt lt ext ref table gt lt external modules gt P80RUN LIB P80RAR LIB P80RMX LIB where e lt program module gt is the relocatable object file created from the Pascal program code file by GENOBJ PASCAL 80 Preparing Programs to Run Under RMX 80 lt ext ref table gt is the file containing the External Reference Table This item is present only if the Pascal program references external objects lt external modules gt represents one or more relocatable object files which contain the code for the external module s This item is present only if the Pascal program references external objects The last three files are the PASCAL 80 libraries required for a Pascal program to run in the RMX 80 environment 7 9 CHAPTER 8 RUN TIME ERROR PROCEDURES During the execution of a PASCAL 80 program various run time errors may occur These errors are divided into three general categories e Data structure errors e Value range errors e nput output errors The interpreter will always detect data structure errors while detection of errors in the other two categories is not automatic Errors in these categories are detected only by in line interpreter p code operations which may or may not be generated by the compiler during the compilation of the Pascal program As is discussed in Appendix C the R compiler directive controls the generation of the range checking cod
32. system A discussion of this can be found in Chapter 2 of the ISIS II User s Guide Under RMX 80 filenames and extensions are files on the Disk File System are defined by the user and DFS device names are defined by the configuration module The device names CI and CO are predefined to be input from the Terminal Handler and output to the Terminal Handler respectively A complete file designator has the same format in Pascal programs running in both the ISIS II and RMX 80 environments This common format is as follows X device filename extension where e device is a two character alphanumeric designation for a device If the file is a DFS file device should correspond to a value of the DEVICENAME field in a Device Configuration Table Entry see ICUSO discussion below If the file refers to the Terminal Handler either CI or CO are valid e filename is a one to six upper case non blank alphanumeric characters which specify a portion of the name of a DFS file PASCAL 80 PASCAL 80 Preparing Programs to Run Under RMX 80 e extension is zero to three upper case non blank alphanumeric characters e which are appended to filename to completely specify a Disk File System file The following are valid RMX 80 PASCAL file names CI Input from Terminal Handler CO Output to Termina Handler F1 MYFILE TXT DFS disk file on device F1 HD DATA36 DFS disk file on device HD The Predeclared
33. value 1 gt Run Time Tracing flag value 2 where X y The version and revision of the Pascal Interpreter itself lt size 1 gt The number of bytes available for the code and data of a user program PASCAL 80 PASCAL 80 Operating Instructions lt size 2 gt lt size 3 gt lt size 4 gt The current values ofthe size monitoring variables lt flag value 1 gt lt flag value 2 gt The state of the associated Run Time parameters The possible values of these parameters are On or Off Automatic Program Execution If a code file is specified on the ISIS II command line when invoking PASCAL 80 the PASCAL 80 System is loaded and code filename is executed with no further user input For example typing PASCAL COMP EX PAS would result in the following PASCAL 80 Vv r PASCAL 80 Compiler Vv r COMPILING EX PAS Symbol table space remaining 12234 bytes 37 lines compiled PASCAL 80 Vv r 2 Interrupting Program Execution INTERRUPT switch 3 on the Intellec system front panel causes the currently executing Pascal program to cease execution and causes control to be returned to the PASCAL 80 System command handler An error message is displayed along with the Segment Procedure and Instruction where execution was suspended Operating the PASCAL 80 Compiler Command Line Syntax for the Compiler The command line syntax for compiling a Pascal program is as follows COMP filename directives
34. where filename is the name of the source code file If the filename is not given an error message is printed and control is returned to the PASCAL 80 system The source filename may be specified in the following ways Name Specified Name Used lt filename gt lt ext gt lt filename gt lt ext gt lt filename gt lt filename gt PAS lt filename gt lt filename gt Operating Instructions The directives field is an optional sequence of compiler directives see below Each directive must be separated from the preceding directive by one or more spaces Where directives have brackets the left hand bracket may occur zero one or more spaces after the body of the directive To terminate the sequence press return If a COMP command is longer than one line on your console which must not be greater than 122 characters you can continue it by entering an ampersand amp before the carriage return The ampersand cannot appear within a directive name or file name COMP creates a work file named P8OWRK TMP on the diskette to which the output code file is directed If you have a file by this name on the output diskette it will be destroyed Compiler Directives The PASCAL 80 System compiler recognizes various directives which are used to control various phases and details of the compilation process These directives are partitioned into two classes The first class is the command line directives which are specified on the
35. will be packed if and only if the prefix PACKED appears immediately preceding the last occurrence of the symbol ARRAY In particular at PACKED ARRAY 0 10 OF ARRAY 0 10 OF char will not be packed while a2 ARRAY 0 10 OF PACKED ARRAY 0 10 OF char a3 PACKED ARRAY 0 10 OF PACKED ARRAY 0 10 OF char a4 PACKED ARRAY 0 10 0 10 OF char will all be packed two characters per word A components of a PACKED ARRAY may not be passed as a variable parameter to a FUNCTION or PROCEDURE It may however be passed as a value parameter The RECORD Type A variable of type RECORD has values which are composed of a fixed number of fields with no restriction on the type of each field In PASCAL 80 the RECORD type is as specified in Standard Pascal If the RECORD declaration is prefixed by the reserved word PACKED the com piler will attempt to minimize storage requirements by packing more than one field into each word However this packing is subject to the following restrictions l Packing will occur only with adjacent fields of subrange or scalar type Any field which is of a structured type ARRAY RECORD SET string or FILE will always begin on a word boundary Packing will never cross word boundaries This implies that two or more fields will be packed into a word only if the total number of bits required for their combined representation is less than 16 The prefix PACKED must appear before every occurrence of RECO
36. 1 Attempted seek on write only output file 32 Can tdelete an open file o 33 Illegal system call parameter 34 Bad RETSW argument to LOAD 35 Attempt to extend a file opened for input by seeking past end of file ISIS II Error Messages PASCAL 80 F 2 201 Unrecognized switch 202 Unrecognized delimiter character 203 Invalid command syntax 204 Premature end of file 206 Illegal disk label 207 No END statement found in input 208 Checksum error 209 Illegal records sequence in object module file 210 Insufficient memory to complete job 211 Object module record too long 212 Bad object module record type 213 Illegal fixup record specified in object module file 214 Bad parameter in a SUBMIT file 215 Argument too long in a SUBMIT invocation 216 Too many parameters in a SUBMIT invocation 217 Object module record too short 218 Illegal object module record format 219 Phase error in LINK 220 Noend of file record in object module file 221 Segment overflow during Link operation 222 Unrecognized record in object module file 223 Fixup record pointer is incorrect 224 Illegal record sequence in object module file in LINK 225 Illegal module name specified 226 Module name exceeds 31 characters 227 Command syntax requires left parenthesis 228 Command syntax requires right parenthesis 229 Unrecognized control specified in command 230 Duplicate symbol found 23 File already exists 232 Unrecogni
37. 3 lt n gt 4 lt n gt gt 5 or lt n gt lt Q Figure 3 6 Example of Predeclared Procedure exit 3 8 PASCAL 80 Predeclared Procedures gotoxy lt column gt rows Positions the CRT cursor to We column and row Both arguments must be integers Position E 0 1 is the top left corner of the screen oo x s setpointer p v Places the addres of the variable v into the pointer variable p E portinput p V Inputs a value from the 8080 8085 vo pora p rand set variable v to that value portoutput p e B Outputs the value of the fer expression e to the 8080 8085 I O port p errorset p Causes p to become the current error procedure The procedure p must bea parameterless procedure declared at the global level of the Pascal program The errorset p procedure may be executed as often as desired each invoca tion causes the previous error procedure to be overridden by the new pro cedure specified by errorset String Manipulation Routines length s integer Returns the current value of the dynamic engi of the SHANE S See figure 3 7 for an example pos lt pattern gt s integer Returns the position in the string s of the first occurrence of the string lt pattern gt If lt pattern gt is not a substring of s 0 is returned The position returned is the position of the first character of the match See figure 3 7 for an example concat s1 sj uie Returns
38. ASCAL 80 Run Time System is invoked it responds as specified above and displays its prompt character gt to indicate that it is waiting for a command which is defined as follows command lt file command gt lt direct command gt lt file command gt lt code filename gt lt options gt lt direct command gt TRACEON TRACEOFF QUIT SIZEON SIZEOFF STATS The code filename specifies a compiled Pascal program which will be loaded by the RTS and executed The meaning of the lt options gt field is determined by the pro gram being executed It allows for the specification of data files execution options and directives at the time of invoking the program The next two commands TRACEON and TRACEOFF are used to control the tracing facility of the PASCAL 80 System The QUIT command returns control to the ISIS II Command Line Interpreter The SIZEON and SIZEOFF commands are used to control the run time monitoring of the STACK size and HEAP size The STATS command causes certain run time statistics to be displayed Examples of valid commands are as follows 2COMP TEST PAS gt TEST 2TRACEON gt TRACEOFF gt QUIT The first command will compile the Pascal source program file TEST PAS The second command will execute the Pascal object program TEST COD which the previous compilation just generated The third command will turn on the TRACE flag so that the line number of each executed program state
39. EGMENT on the global level e Each SEPARATE PROCEDURE and FUNCTION can reference every global constant type variable PROCEDURE and FUNCTION PASCAL 80 PASCAL 80 Separate Compilation Program Linkage Relocation and Execution Main Program Compilation Unit Source on SIX1 PAM partitioned program sixl const header This is procedure type procname string 10 var level integer Segment procedure aa Separate segment procedure bb separate segment procedure cc separate function increment i integer integer begin writeln level 1 3 5 increment i 1 end increment begin sixl level 1 write This is the main program level increment level aa end sixl Component 1 Compilation Unit Source on SIXIl PAl Component sixlci segment procedure aa var name procname begin name aa write header name level increment level bb end aa begin end sixlcl Component 2 Compilation Unit Source on SIX1 PA2 component sixlc2 segment procedure bb begin write header bb level increment level ec end bb segment procedure cc begin write header cc level increment level end cc begin end sixlc2 Figure 6 1 A Partitioned Pascal Program Code File Construction The final executable code file is constructed from the code files of all of the com pilation units The
40. EIGHTI PAS 8 1817 1872 2002 BLOCKS USED Double Density Release Diskette DIRECTORY OF F1 970058 02 NAME EXT BLKS LENGTH ATTR NAME EXT BLKS PASCAL 8l 10053 PASCAL RES 102 COMP COD 293 36864 JOIN COD 25 GENOBJ COD 17 2048 P80EXT LIB 2 P80RUN LIB 378 47569 P80ISS LIB 236 P8ORAR LIB 205 25603 P80ISS PLB 238 EX PAS 8 810 BUFFER PAS 8 ERROR PAS 8 847 SEEKEX PAS 49 PEOPLE DAT 7 700 FIG31 PAS 8 FIG32 PAS 9 982 FIG33 PAS 10 FIG34 PAS 12 1349 FIG35 PAS 4 FIG36 PAS 13 1480 FIG37 PAS 8 FIG38 PAS 10 1152 SIX3 PAS 6 ASUM OBJ 2 100 ASUM LST 15 ASUM ASM 7 733 PSUM PLM 4 PSUM OBJ 3 130 PSUM LST 22 SIX3 CSD 2 111 SIXl PAM 6 SIXl PA2 4 347 SIX1 PAl 4 SIXl1 CSD 3 193 EIGHT1 PAS 8 1817 1926 4004 BLOCKS USED LENGTH 12800 3072 127 29588 29843 878 6120 869 1189 366 811 544 1714 361 2585 576 279 795 LENGTH 12800 3072 127 29588 29843 878 6120 869 1149 366 8ll 544 1714 361 2585 576 279 795 ATTR ATTR K 1
41. ERENCE TEXTS APPENDIX K DIRECTORY OF RELEASE DISKETTES TABLES TABLE TITLE PAGE F 1 Nonfatal Error Numbers Returned by System Calls oda wa Ado Ed area bore F 3 A F 2 Fatal Errors Issued by System Calls F 3 ILLUSTRATIONS FIGURE TITLE PAGE FIGURE TITLE PAGE 1 1 Program Development Cycle 1 3 3 7 Examples of String Manipulation 3 1 Examples of Predeclared Procedures Routines length pos concat copy insert reset rewrite get put and close 3 2 and delete oooooooo oo ooo 3 10 3 2 Examples of Predeclared Procedures 3 8 Examples of Character Array Routines reset seek and get ooooooono 3 3 scan moveleft moveright and fillchar 3 11 3 3 Examples of Predeclared Procedures 4 1 Main Memory Layout for a 64KB System 4 3 read and readln eve s 3 3 6 1 A Partitioned Pascal Program 6 3 3 4 Examples of Predeclared Procedures 6 2 Compiling and Joining a Partitioned l new mark and release 3 6 Pascal Program siure e a 6 4 3 5 Examples of Predeclared Procedures 6 3 A Pascal Program With External Linkages 6 7 Ord and Chl carrere rer XS OI be eR 3 7 8 1 Use of the errorset Procedure 8 2 3 6 Example of Predeclared Procedure exit 3 8 CHAPTER 1 INTRODUCTION General Description Pascal is a highly structured computer programming language devised in 1970 by Professor Niklaus Wirth of Zurich It i
42. Files Input and Output In PASCAL 80 input is a predeclared file variable of type INTERACTIVE and output is a predeclared file variable of type TEXT In a Pascal program executing under ISIS II the initialization logic in the surrounding environment automatically connects input to the ISIS II CI file and output to the ISIS II CO file Under RMX 80 these automatic connections are also made where CI corresponds to ter minal input and CO to terminal output as discussed above Therefore as under ISIS II an RMX 80 PASCAL program does not have to open the terminal files input and output DFS Service Operations In addition to supporting the data storage and transfer operations of Pascal the Disk File System in RMX 80 also provides a number of Directory Maintenance Ser vices and other service operations While procedures corresponding to these service operations are not predeclared in the surrounding environment they may easily be invoked by a Pascal program using the external linkage features of PASCAL 80 Run Time Error Handling As in the ISIS II environment an RMX 80 PASCAL task can specify a user error procedure to be invoked upon detection of a run time error by the PASCAL 80 Run Time System In the absence of such a specification the default system error procedure will be invoked upon a run time error This procedure will attempt to out put an error message to the Terminal Handler will then cause the task to exit and henc
43. In the absence of this directive the compiler uses the file name source file name ERT The External Reference Table contains an external reference for each external object declared in the Pascal program and defines the relationship between the location of gt each external object and the location of its Indirect Reference Pointer in the global environment of the Pascal program The address of the External Reference Table itself is defined by the PUBLIC symbol PQETAB Program Execution with External Objects In order to execute a PASCAL 80 program which references external objects it is necessary to e I Compile the Pascal program Compile and or assemble the external module s Link the external module s together with the External Reference Table Locate the module produced by step 3 Load the module into memory and invoke the PASCAL 80 Run Time System RH gt N Each of these steps is explained in detail below using the programs in figure 6 3 as an example Compile the Pascal Program If the Pascal program is a single compilation unit then compile it to produce the code and External Reference Tabie file If the Pascal program is a partitioned pro gram compile the main module and each of the COMPONENTS The compiler will generate the External Reference Table file when compiling the main module then invoke the JOIN utility to combine all the code files into one resultant code file _ For example the comman
44. Pascal program code file by GENOBJ and should be the first file on the list e lt external ref table gt is the file containing the External Reference Table This item is present only if the Pascal program references external objects e lt external module gt represents one or more object files which contain the code for the external module s This item is present only if the Pascal program references external objects e The last three files are the Pascal libraries required for a Pascal program to run under ISIS II The ISIS II User s Guide should be consulted for complete operating instructions for the LINK utility Locating the Object Module The relocatable object module produced by the previous linking operation must now be located to absolute locations This procedure is performed with the ISIS II LOCATE utility as follows LOCATE lt link file gt TO lt output file gt lt controls gt 6 13 Separate Compilation Program Linkage Relocation and Execution PASCAL 80 The only restriction on this command is that the CODE segment must be located to an even byte boundary Other than this the user is free in the choice of locations for the various segments Program Execution The linked and located Pascal program may now be loaded and executed simply by presenting its name to the ISIS II command line interpreter For example MYPROG lt options gt will load and execute this Pascal program and wil
45. RD or ARRAY in order for the fields themselves to be packed A field of a PACKED RECORD may not be passed as a variable parameter to a FUNCTION or PROCEDURE It may however be passed as a value parameter PASCAL 80 PASCAL 80 The String Type Language Features PASCAL 80 contains he neon ae dui be ihe This oe is le to a PACKED ARRAY OF khar but it also o a o aud byte a String may be uon t to 255 characters 80 ch r acters Being th d default iuh in addition the individual characters of a string may be referenced using an index of 1 to the length of the string Thef ollowing examples illustrate the use of strings ch char NE QU cp theta D up T Mc name string 30 en The variable name is of type xui die o0 os String with a maximum length Yon sad of 30 characters s address string oo The variable address is 5 0f type string with a maximum E length of 80 characters name George Washington read input address ch namel3 The SET Type In PASCAL 80 as n Standard Pascal the SET type defines the set of all subsets of values of a base type which must be either a scalar type or subrange type The maximum number of elements in a set in PASCAL 80 is 4080 each one of which must satisfy the following ord element 0 i The FILE Type As in Standard Pascal a FILE is a structure consisting of a sequence of identical 1 e of the
46. SS procedure even if the value being returned occupies one byte or less Similarly if an external function is coded in assembly language it must always return its value in the HL register pair If it normally would return a byte in the A register 1t should copy the result in A to the L register and clear the H register prior to returning to the Pascal program These details of external module linkage are illustrated by the programs in figure 6 3 The FORTRAN 80 convention for calling a function with n arguments is to pass n l addresses to the function routine The first address is the location for storing the result and the next addresses are the locations of the n arguments since in FORTRAN 80 all arguments are passed by reference Therefore if you want to call an external function of n arguments written in FORTRAN 80 from your Pascal program you should declare an external procedure of n 1 parameters each of which is a VAR parameter and the first one is the variable which receives the result of the FORTRAN 80 function The External Reference Table If a PASCAL 80 program references one or more external objects the compiler automatically generates an External Reference Table on an ISIS II relocatable PASCAL 80 PASCAL 80 Separate Compilation Program Linkage Relocation and Execution object file The ETAB lt file name gt compiler directive allows the name of the exter nal reference table file to be specified
47. V DO DOWNTO ELSE END FOR FILE FORWARD FUNCTION GOTO IF IN LABEL MOD NOT OF OR PACKED PARTITIONED PROCEDURE PROGRAM PUBLIC RECORD REPEAT SET SEGMENT SEPARATE THEN TO TYPE UNTIL VAR WHILE WITH NIL In this manual reserved words are written in upper case letters to emphasize their interpretation as single symbols with a fixed meaning They may not be used in any context other than that explicit in their definition In particular they may not be used as identifiers Identifiers These are names denoting constants types variables procedures and functions An identifier must begin with a letter which may be followed by any combination and number of letters and digits However in PASCAL 80 only the first eight characters of any identifier are significant Matching upper and lower case letters are equivalent in identifiers and reserved words In particular the two identifiers sample and SAMPLE refer to the same variable Similarly packed and PACKED are equivalent names for the same delimiter APPENDIX C SUMMARY OF COMPILER DIRECTIVES Command Line Directives A description of the available command line directives follows NOLIST No list file is produced NOCODE No intermediate code file is produced ERRLIST The listing is limited to those lines containing syntax errors LIST external fiie name Specifies the file to which the listing is to be directed The default is lt source filename gt
48. X 80 environment These extensions give an RMX 80 PASCAL program the ability to interface with the complete facilities of RMX 80 This capability together with the use of the RMX 80 Interactive Configuration Utility ICU80 allows a user to construct an RMX 80 application system entirely in the Pascal pro gramming language without the need to resort to either PL M or assembly language for certain modules Under RMX 80 PASCAL 80 input and output operations normally use the full or minimal Terminal Handler and the Disk File System rather than the ISIS II func tions used in the ISIS II environment Alternatively you can omit the Terminal Handler and or Disk File System and just use direct port input and output Program Structure Under RMX 80 Under RMX 80 programs run as a series of tasks under the control of the RMX 80 Nucleus These tasks communicate with each other by sending and receiving messages to and from exchanges One of the tasks in an RMX 80 application system may be coded in Pascal this program may make full use of all of the language features of PASCAL 80 The other user tasks if any in addition to any external subroutines called by the Pascal task may be written in PL M 80 FORTRAN 80 or ASM 80 depending on the nature of the functions to be performed The RMX 80 task written in Pascal is coded identically to one coded to execute under ISIS II no adjustments at the source language level need be made for the dif fere
49. York 1979 PASCAL An Introduction to Methodical Programming W Findlay amp D A Watt Computer Science Press 1978 Microcomputer Problem Solving Using PASCAL Kenneth L Bowles Springer Verlag New York 1977 Programming in PASCAL Peter Grogono Addison Wesley 1978 An Introduction to Programming and Problem Solving with PASCAL Schneider Weingart Perlman John Wiley amp Sons 1978 Structured Programming and Problem Solving with PASCAL Richard B Keiburtz Prentice Hall 1978 J 1 T APPENDIX K DIRECTORY OF RELEASE DISKETTES The PASCAL 80 System software is contained on each of two 2 release diskettes single and double density The directory listing of each of these diskettes is as follows Single Density Release Diskette DIRECTORY OF F4 9500065 02 NAME EXT BLKS LENGTH ATTR NAME EXT BLKS PASCAL 81 10053 PASCAL RES 102 COMP COD 293 36864 JOIN COD 25 GENOBJ COD 17 2048 P8OEXT LIB 2 PBORUN LIB 378 417569 PBOISS LIB 236 P8ORAR LIB 205 25603 P80ISS PLE 238 EX e PAS 8 810 BUFFER PAS 8 ERROR PAS 8 847 SEEKEX PAS 49 PEOPLE DAT 7 700 FIG31 PAS 8 FIG32 PAS 9 982 FIG33 PAS 10 FIG34 PAS 12 1349 FIG35 PAS Y FIG36 PAS 13 1480 FIG37 PAS 8 FIG38 PAS 10 1152 SIX3 PAS 6 ASUM OBJ 2 100 ASUM LST t5 ASUM ASM T 133 PSUM PLM y PSUM 0PJ 3 130 PSUM LST 22 SIX3 CSD 2 111 SIXI PAM 6 SIX PA2 y 347 SIX1 PA y SIXI CSD 3 193
50. able to running Pascal programs in the RMX 80 environment Chapter 8 Run Time Error Procedures which gives instructions for declaring and using user defined error procedures Appendix A Summary of Operations allowable operations among data types which presents in tabular form the Appendix B PASCAL 80 Vocabulary which contains all of the operators and reserved words in the PASCAL 80 programming language Appendix C Summary of Compiler Directives which describes the directives for the compiler Appendix D Compiler Error Messages which lists all errors that can be signaled during the compilation of a Pascal program Appendix E Run Time Errors which is a listing of the error messages issued by the system default error procedure Appendix F ISIS II Error Messages which is a listing of the error messages issued by ISIS II Appendix G Syntax Summary which summarizes the syntax of legal PASCAL 80 programs Appendix H Summary of Extensions to Standard Pascal which summarizes all extensions to Standard Pascal provided by PASCAL 80 Appendix I Implementation Details which presents the format of the predeclared data types in PASCAL 80 lists certain implementation size limits and summarizes the differences between PASCAL 80 and Standard Pascal Appendix J Pascal Reference Texts which lists a number of books that are of interest to the Pascal programmer Ap
51. ading valid only on global level Error in real number digit expected String constant must not exceed source line Integer constant exceeds range PASCAL 80 PASCAL 80 250 251 252 253 259 261 300 302 303 304 398 399 400 401 402 403 404 405 406 407 Too many scopes of nested identifiers Too many nested procedures or functions Too many forward references of procedure entries Procedure too long Expression too complicated Too many segment declarations Division by zero Index expression out of bounds Value to be assigned is out of bounds Element expression out of range Implementation restriction Implementation restriction Illegal character in text Unexpected end of input Error in writing code file not enough room Error in reading include file Error in writing list file not enough room Error in reading globals file Error in writing globals file Wrong version of globals file Compiler Error Messages APPENDIX E e RUN TIME ERROR MESSAGES In the absence of a user specified error procedure a run time error will cause the system default error procedure to be invoked This procedure displays an error message and then forces the current program to terminate Each run time error A causes a specific message to be displayed along with the Segment number Procedure number and Instruction offset of the offending operation By referring to the compiler listin
52. am When the TRACE flag is set the line number of each program statement being executed is output to CO enclosed in brackets and Using this information together with the com piler listing which associates line numbers with program statements a programmer may more easily determine what the program is doing As an example of the tracing output if the program were to ask for a customer name 137 138 Customer name 139 might be displayed if the TRACE flag were set while Customer name would only be displayed if the TRACE flag were not set The TRACE Flag The TRACE flag may be manipulated in two ways The TRACEON command will set the flag and the TRACEOFF command will reset the flag Additionally press ing the INTERRUPT 4 switch on the Intellec system front panel will cause the TRACE flag to toggle In particular every time the INTERRUPT 4 switch is press ed the TRACE flag will be set if it was reset or will be reset if it was set This allows for selectively tracing only those portions of a program which are in question and a executing the remainder of the program normally Tracing Instructions In order for the PASCAL 80 System to trace a program or portions of a program tracing instructions must be present in the compiled code The PASCAL 80 com piler normally inserts these instructions in the object code but they may be omitted using the embedded compiler directive T When the compile
53. am by the Pascal interpreter using the standard PL M calling convention The details of that convention and their relationship to PASCAL 80 are as follows e The value of an actual parameter is passed to an external procedure if the corresponding formal parameter is specified as a value parameter The address of the actual parameter is passed if the corresponding formal parameter is specified as a VAR or variable parameter e If the external procedure for function is coded in PL M or FORTRAN each Pascal actual parameter is assigned to its corresponding PL M or FOR TRAN formal parameter e If the external procedure or function is coded in assembly language it will find its arguments in the standard locations A single parameter is passed in the BC register pair Fora two parameter procedure or function the first parameter is passed as above and the second is passed in a similar fashion in the DE register pair For a procedure or function with more than two parameters the last two parameters are passed as described above next to last in BC last in DE and the remainder are found on the stack They are pushed onto the stack in order from left to right in the parameter list followed by the return location into Pascal which is the state of the stack when the called procedure or function begins execution e The only restriction to the standard PL M calling convention is that an external PL M function must be an ADDRE
54. ample a DFS Delete Request Message type is declared as follows type deletemsg message homeexch exchange respexch exchange status integer fileptr fnameblock end The MESSAGE type is similar to the RECORD type with the following differences In a MESSAGE type e An unnamed six byte field preceds the first declared user field Certain parameters to some predeclared procedures must be of type message e The PACKED prefix is not allowed Note that a MESSAGE type declaration does not declare the LENGTH and TYPE fields of the RMX 80 message These fields of a message are manipulated by the predeclared procedures rqsetlt and rggetlt described below PASCAL 80 PASCAL 80 Preparing Programs to Run Under RMX 80 In order to allow for the extra byte in these MESSAGE types the RMX 80 predeclared procedures pass to the external world the address of the second byte in the MESSAGE not the address of the beginning of the Pascal MESSAGE Con versely when an RMX 80 predeclared procedure receives a message address from a nucleus operation it decrements it by one byte before returning it to the Pascal program When a Pascal program declares a private variable to be of type MESSAGE the compiler allocates storage for it and the item is addressed as described above In particular Pascal addresses the first byte of the MESSAGE while RMX 80 addresses the second byte In order to allow for a MESSAGE variable to b
55. an 10 8 ca 91 3 scan 10 X ca 9 4 moveleft ca cb sizeof ca copy ca to cb both ways writeln cb moveright ca cb sizeof ca writeln cb moveleft ca ca l 9 the incorrct way to move characters up by one position writeln ca moveright cb cb 1 9 the correct way writeln cb sa ABCDEFGHIJKLMNOPQRSTUVWXYZ writeln sa fillchar sa 1 1 25 0 a string is a packed array of char writeln sa end 3 8 Executing this program results in the following output 4 2 10 5 l 10 0123456789 e 0123456789 0000000000 0012345678 ABCDEFGHIJKLMNOPQRSTUVWXYZ 00000000000000000000000002 Figure 3 8 Examples of Character Array Routines scan moveleft moveright and fillchar CHAPTER 4 OPERATING INSTRUCTIONS The PASCAL 80 System is composed of a Run Time System RTS and a compiler which itself executes on the Run Time System The PASCAL 80 compiler converts PASCAL source code into an intermediate code which is then interpreted by the Run Time System The ISIS II text editor is used to create the Pascal source file s The PASCAL 80 compiler is then used to compile the source programs so that they may be executed on the RTS A listing of the PASCAL 80 program is provided by the compiler during compilation Any error messages are included in this listing Getting Started with PASCAL 80 Each user is provided with all the software that makes up the PASCAL 80 develop m
56. ar to that of a forward segment procedure declaration j The syntax of a PARTITIONED program is as follows lt partitioned program lt partitioned program heading block lt partitioned program heading PARTITIONED PROGRAM ident PARTITIONED PROGRAM lt ident gt lt file id lt file id 3 block label deciaration part constant declaration part type declaration part variable deciaration part separate procedure and function heading part procedure and function heading part statement part 6 1 Separate Compilation Program Linkage Relocation and Execution separate procedure and function heading part separate procedure or function heading separate procedure or function heading separate procedure heading separate function heading separate procedure heading SEGMENT procedure heading SEPARATE separate function heading SEGMENT function heading SEPARATE The syntax of a COMPONENT is as follows component component heading component block component heading COMPONENT identifier component block lt segement procedure and function declaration part BEGIN END segment procedure and function declaration part segment procedure or function declaration segment procedure or function declaration segment procedure declaration segment function de
57. art constant declaration part type declaration part variable declaration part procedure and function declaration part statement part Program Heading The program heading names the program which allows the predeclared procedure exit lt name gt described below to force the program itself to cease execution Any file identifiers if present in the heading are ignored program heading PROGRAM identifier Or program heading PROGRAM lt identitier gt lt tile identifier list il The following are legal program headings PROGRAM sort PROGRAM convert input output PROGRAM generate listing Label Declaration Part Any statement in a PASCAL 80 program may be labelled with an unsigned integer label followed by a colon This allows references to this statement by goto statements Any such label must be declared in the label declaration part which has the form LABEL label lt label gt where lt label gt is an unsigned integer of at most four digits Examples of label declarations are LABEL 1 2 3 4 5 LABEL 1999 2999 6789 2 Language Features PASCAL 80 2 2 Constant Declaration Part A constant declaration defines an identifier as a synonym for a constant The general form for this declaration is CONST identifier constant lt identifier gt constant where lt constant gt is either a number a constant string or a co
58. art declares procedures and functions which are defined and allocated externally to the Pascal program The compiler allocates an indirect reference pointer in the global environment for each such exter nal procedure or function These procedures are assumed to exist in memory in 8080 8085 machine executable form and the Pascal interpreter CALLs them using the standard PL M subroutine calling convention Since the only two data types which can be passed as parameters using this convention are the BYTE type and the ADDRESS type a procedure or function heading within a public declaration record 6 5 Separate Compilation Program Linkage Relocation and Execution 6 6 has a restricted form In particular if the size of a parameter is not greater than one word two bytes it may be passed by value or by reference VAR However if the size of a parameter is greater than one word it must be a VAR parameter Addi tionally the size of the result of a function must not be greater than one word The general structure of a program which accesses external objects is as follows program program heading block block public declaration part lt label declaration part constant declaration part type declaration part variable declaration part procedure and function declaration part statement part public declaration part empty public declaration record An example of such
59. ause the message File Tanslation Program to be a heading on each page of the compiler listing C 3 Summary of Compiler Directives The next two options deal with list file format Causes a top of page on the list file Causes a top of page on the list file if the current position on the page is within 10 lines from the bottom of the page C 4 PASCAL 80 APPENDIX D 0 COMPILER ERROR MESSAGES 1 Errorin simple type 2 Identifier expected 3 PROGRAM expected a 4 y expected 5 expected 6 Illegal symbol maybe missing on the line above T Error in parameter list e 8 OF expected 9 expected 10 Errorintype 11 expected 12 expected 13 END expected 14 expected e 15 Integer expected 16 expected E BEGIN expected 18 Error in declaration part 19 Error in lt field list gt 20 expected 21 expected 50 Error in constant 51 expected 52 THEN expected 53 UNTIL expected 54 DO expected 55 TO or DOWNTO expected in for statement 56 iF expected 57 FILE expected 58 Error in factor bad expression 59 Error in variable 101 Identifier declared twice 102 Low bound exceeds high bound 103 Identifier is not of the appropriate class 104 Undeclared identifier 105 Sign notallowed 106 Number expected 107 Incompatible subrange type
60. bine SIX1 COM SIX1 CO1 and SIXI CO2 into SIX1 COD JOIN SIX1 COM SIX1 CO1 SIX1 CO2 TO SIX1 COD The sequence of commands shown in figure 6 2 will compile each of the compilation units shown in figure 6 1 and then combine the resultant code files into an executable code file The file SIX1 SYM is used as the global symbol table file since none of the compilation commands specify a GLOBAL directive As an aid to understanding this facility the release diskette contains the three source files SIX1 PAM SIX1 PAl and SIXI PA2 as well as the file SIXI CSD which is a SUBMIT file containing the commands shown in figure 6 2 Linking with non Pascal Modules For some applications it may be necessary or desirable to code one or more pro cedures or functions in a language other than Pascal These external procedures and functions can be written in PL M 80 FORTRAN 80 or 8080 8085 Assembly Language and translated by the appropriate language processor The resultant relocatable object module s can be linked located and then executed as an integral part of the PASCAL 80 program Refer to other Intel manuals cited in the preface for instructions on translating and linking subroutines written in other languages In the remainder of this section a set of external procedures and functions together with any associated data structures will be referred to as an external module PASCAL 80 Extensions n order to be able to communicate with an
61. bject module of a Load and Go Pascal program Accordingly the section in Chapter 6 which discusses Load and Go program generation should be referenced The only difference between the two procedures is the format of the GENOBJ command When generating the relocatable object module of an RMX 80 PASCAL task this utility is invoked by GENOBJ lt code file gt TO lt obj file gt FREE n RMX where the inclusion of the RMX option causes GENOBJ to reference RMX 80 specific Resident System procedures instead of the default ISIS II specific procedures The Interactive Configuration Utility The RMX 80 Interactive Configuration Utility ICUSO is a utility used to automate the configuration linking and locating operations described in the RM X 80 User s Guide 1CU80 is used to generate the configuration object module the controller addressable memory CAM module and a submit file containing the link and locate commands required to build the RMX 80 application system ICUS0 obtains its input data from two sources a description file suplied to ICU80 when it is invoked and data entered from the console by the user in response to prompts from ICU80 One of the features of ICUSO is that an updated description file can be generated which contains all of the additions and modifications the user made during the session with ICUSO This file may then be used as the initial descrip tion file the next time ICUSO is invoked When using 1CU80 to confi
62. ck and the top of the heap i in 16 bit words Arithmetic Functions abs x lt type of x gt Computes the absolute value of x The type of x must be either integer or real and the type of the function is the type of x sqr x type of x gt Computes x x The type of x must be either integer or real and the type of the function is the type of x 3 5 Predeclared Procedures This program illustrates the use of the new mark and release program three4 type intarray array 0 10 of integer var i integer htop htopl integer buffer intarray begin mark htop new buffer mark htopl writeln ord htopl ord htop for i 0 to 10 do buffer il i i process the array release htop The pointer variable buffer now PASCAL 80 predeclared procedures record the top of the HEAP allocate an array of integers from the top of the HEAP This moves the top of the HEAP upwards by 22 bytes record the new HEAP top display the amount of allocated space set the values of the array Set the top of the HEAP back to its original value which was saved in htop points to locations above the valid area of the HEAP and must not be used until using the new procedure again it points to a valid array end 3 4 Executing this program will result in the following output 22 Figure 3 4 Examples of Predeclared Procedures new mark a
63. claration segment procedure declaration SEGMENT procedure declaration segment function declaraction SEGMENT function declaration For an example of a Pascal program which has been divided into three compilation units figure 6 1 should be referenced As is seen in this example three SEGMENT PROCEDURES have been removed from the main program and placed in the COM PONENTSs The complete program is composed of a main PARTITIONED PRO GRAM sixl and two COMPONENTS sixlcl and six1c2 Each of these compila tion units resides on a separate diskette file The PARTITIONED PROGRAM six1 is on SIXI PAM the COMPONENT sixicl is on SIX1 PA1 and the COMPO NENT six1c2 is on SIX1 PA2 Note that the structure of both a PARTITIONED PROGRAM and a COMPO NENT are similar to that of a standard PROGRAM The differences are noted below A PARTITIONED PROGRAM has the following characteristics e The reserved word PARTITIONED in the program heading e The presence of one or more SEPARATE PROCEDURE or FUNCTION declarations A COMPONENT has the following characteristics e The reserved word COMPONENT which replaces PROGRAM in the heading e No global labels constants types or variables may be declared the complete global environment is declared in the main PARTITIONED PROGRAM There are no program statements in the outer block just a BEGIN followed by an END e Fach SEPARATE PROCEDURE and FUNCTION must be declared as a S
64. clared data type these public declaration records will duplicate type declarations In order to allow for this situation and not cause a duplicate type or constant declaration error the compiler will allow types and constants to be redeclared in public declaration records if the new declaration is identical to the original Figure 6 3 contains an example of a type range which is declared in one public declaration record and then redeclared in another This situation is necessary since each module must declare the range type independently of any other module A public declaration record may be included in the source file using the I lt file name gt construct in the same way as any other Pascal source text as is demonstrated in figure 6 3 see Appendix C for details PASCAL 80 PASCAL 80 Program with external linkages Source on SIX3 PAS Separate Compilation Program Linkage Relocation and Execution program six3 me we Se w w public asum type range 0 1000 var arslt integer function asum a b c range integer end asum public psum type range 0 1000 var prslt integer function psum a b c range integer end var i k range result integer begin 1 10 j 12 k 14 result asum i j k writeln result arslt result psum i j k writeln result prslt end six3 External module to compute the SUM of the three argumen
65. command line after the name of the PASCAL 80 source file to be compiled The second class is the embedded directives which are embedded in the text of the program being compiled The command line directives are described below a summary of all directives is in Appendix C Compiler Command Line Directives A description of the available command line directives follows NOLIST No list file is produced NOCODE No intermediate code file is produced ERRLIST The listing is limited to those lines containing syntax errors LIST external file name Specifies the file to which the listing is to be directed The default is lt source filename gt LST CODE external file name Specifies the file to which the code is to be directed The default is lt source filename gt COD NOECHO Error lines are echoed on the console unless this directive is specified PASCAL 80 PASCAL 80 GLOBAL external file name Specifies the global symbol table file when separately compiling a parti tioned Pascal program The default is lt source filename gt SYM WORKFILE lt device gt Specifies which diskette device is to be used for the compiler s workfile P80WRK TMP The default value is the device of the output code file DATE lt date gt Specifies the date to be included in the page heading of the compiler listing The lt date gt parameter is any sequence of nine or fewer characters not con taining pare
66. d PASCAL COMP SIX3 will compile SIX3 PAS and generate the following three files SIX3 COD The executable code file SIX3 LST The compiler listing file SIX3 ERT The external reference table file Compile and or Assemble the External Module s Translate each of the external modules into 8080 8085 machine executable code using an appropriate language processor Ensure that each external reference in the Pascal program is matched by exactly one PUBLIC declaration in the collection of external modules Separate Compilation Program Linkage Relocation and Execution 6 10 For example the commands PLM80 PSUM PLM ASM80 ASUM ASM will produce the following files PSUM OBJ The relocatable object file PSUM LST The compiler listing file ASUM OBJ Therelocatable object file ASUM LST The assembler listing file Link the Modules Together Using the ISIS II LINK utility link all of the external object modules together with the External Reference Table and the library file PSOEXT LIB into one relocatable object module NOTE The file containing the External Reference Table must be the first file in the list of input files to LINK so that the External Reference Table itself is situated at the beginning of the external module The format of the LINK command is as follows LINK ert file PBOEXT LIB E1 Ek TO code file where lt El gt lt Ek gt are the relocatable object files of the external module s an
67. d any required support library files Using our example programs the appropriate command is LINK SIX3 ERT P80EXT LIB PSUM OBJ ASUM OBJ PLM80 LIB TO EXTMOD OBJ which will create the complete external object module on EXTMOD OBJ Since SIX3 ERT is the first file mentioned in the above command the external reference table will be correctly situated at the beginning of the CODE segment Locate the External Module As is discussed in Chapter 4 during normal operation of PASCAL 80 the Run Time System occupies all of the memory of the Intellec System between the top of ISIS II and the base of the monitor However if a Pascal program references an external module the code for this module must reside in system memory during the execution of the Pascal program In order to allow for this situation the PASCAL 80 Run Time System has a mechanism whereby it can lower the upper boundary of its work space to make room for an external module The activation of this mechanism is described in the next section Use of this mechanism requires that any such external module be located as high as possible in memory so as not to unduly restrict PASCAL 80 s work space The Run Time System can only use the memory up to the bottom of the external module any memory space between the top of the external module and the Monitor will be unused by PASCAL 80 The following discussion presents the considerations when locating an external module in a 64K Intellec System
68. d Go version of a Pascal program or when constructing an RMX 80 PASCAL task since the combined STACK and HEAP value is the max imum free space needed by the program Note however that this free space value is valid only when the program has execution characteristics similar to those during the actual size monitoring and should not be accepted as the maximum free space the program will ever need In particular if the program has declared procedures or functions which are recursive the number of levels of recursion is one factor con tributing to the size of the STACK and therefore each invocation of the program will require a different amount of free space depending upon the recursion level reached Also the particular sequence of procedure calls and returns as well as the pattern of dynamic variable allocation on the HEAP determine the free space used during any specific invocation of a program Displaying the Statistics The execution of the STATS command will cause the value of certain run time variables to be displayed In addition to the size monitoring variables described above the current size of the free space between the top of the HEAP and the bottom of the STACK is also displayed The format of the STATS command is as follows STATS Interpreter Version Vx y Available Free Space size 1 Maximum HEAP Size size 2 Maximum STACK Size size 3 Maximum Combined Size lt size 4 gt Run Time Monitoring lt flag
69. d integer lt set type SET OF base type base type simple type file type FILE OF type TEXT INTERACTIVE FILE lt pointer type type identifier variable declaration part empty VAR lt variable declaration variable declaration variable declaration identifier identifier type procedure and function declaration part procedure or function declaration lt procedure or function declaration procedure declaration function declaration lt procedure declaration 2 procedure heading lt biock gt procedure heading PROCEDURE identifier PROCEDURE lt identifier gt formal parameter section formal parameter section formal parameter section lt parameter group VAR lt parameter group lt parameter group gt identifier identifier type identifier function declaration function heading block function heading FUNCTION identifier result type FUNCTION identifier formal parameter sect on formal parameter section result type 1 PASCAL 80 PASCAL 80 Syntax Summary The BNF Description of Pascal Cont d result type type identifier statement part compound statement statement unlabelled statement
70. dynamic variables are allocated from the HEAP The layout of main memory is illustrated in figure 4 1 PASCAL 80 PASCAL 80 Operating Instructions TOP OF MEMORY FFFFH MONITOR PRE DECLARED PROCEDURES TOP OF PASCAL 80 SPACE F6COH STACK NO REALS EC10H REAL PROCEDURES eem STACK STACK REALS EBCOH HEAP a sul REAL ROUTINES HEAP REALS HEAP NO REALS INTERPRETER TOP OF ISIS II 3880H 0000 Figure 4 1 Main Memory Layout for a 64K B System 1015 2 Operating the PASCAL 80 System Invoking PASCAL 80 To invoke the PASCAL 80 System from ISIS II type the following PASCAL lt directive gt lt code filename gt options The directive is an optional field which when present causes the PASCAL 80 System to be loaded without the code for real numbers The form of this option is R This option is used to increase the memory available to programs which do not use real numbers With the R option specified approximately 2800 additional bytes are available For example PASCAL R PASCAL 80 Vv r No reals 2 The code filename is also an optional field which when present allows for automatic Pascal program execution This feature is described in the Automatic Program Execution section 4 3 Operating Instructions f neither of the optional fields is present PASCAL 80 responds with PASCAL 80 Vv r 2 Command Line Syntax for PASCAL 80 When the P
71. e suspend itself forever In order for the Pascal task to retain control over its execution even in the event of a run time error it is necessary for the program to specify its own error procedure s as described in Chapter 8 The specific actions of an error procedure are dependent gt upon the nature of the run time error the state of the execution environment and the structure of the Pascal task itself such procedures must be designed as an integral part of the total RMX 80 PASCAL application system PASCAL 80 Extensions for RMX 80 RMX 80 PASCAL incorporates a number of language extensions which greatly facilitate the construction of a Pascal task including its communication with other tasks and with the RMX 80 Nucleus These extensions fall into two categories a new predeclared type the MESSAGE type and additional predeclared procedures and functions 7 3 Preparing Programs to Run Under RMX 80 7 4 Need for RMX 80 Extensions There exists a major incompatibility between the format of data structures declared in PASCAL 80 and several RMX 80 data structures This may be understood by observing the following conditions of data storage allocation in PASCAL 80 e Space for data items is allocated in units of words where a word is a two byte quantity aligned on an even byte boundary e If the size of a data item is less than or equal to one word the space allocated for the item will never cross a word boundary In
72. e while the I directive controls the generation of the I O checking code If the code of a compiled Pascal program does not contain this error checking code o the respective run time errors will never be detected All of Chapter 8 exceeds stan dard Pascal During program execution the detection of a run time error by the PASCAL 80 interpreter causes a parameterless error procedure to be invoked In the absence of an error procedure specification by the running program a default error procedure is invoked This default procedure writes an appropriate error message to the file output and then executes exit lt program name gt which causes program termina tion Appendix E lists the error messages which may be generated by the system default error procedure If it is necessary for your program to retain control in the event of a run time error a user declared error procedure may be specified with the predeclared procedure errorset p where p is a parameterless procedure declared at the global level of the Pascal pro gram When a run time error is detected the procedure p is invoked at the point of the error If after performing its actions p terminates normally the interpreter automatically causes an immediate exit from the procedure which caused the error If p executes an exit q operation the interpreter causes an exit from procedure q as usual In either case the procedure which was executing when the run time error wa
73. e declared externally and stil be manipulated correctly the indirect reference pointer of such a variable points to the byte preceding the first byte in the external message This address transformation which is performed automatically transforms the external message into a Pascal MESSAGE and therefore allows it to be handled identically to a private MESSAGE It is not necessary for the programmer to make any adjustment for the extra byte in a MESSAGE the Pascal compiler and run time system effectively mask out its o presence In particular the PUBLIC symbol which names an external RMX 80 message should be bound as in non Pascal applications to the first byte of the LINK field which from the viewpoint of RMX 80 is the beginning of the message Predeclared Procedures and Functions for RMX 80 The following procedures and functions are predeclared in the Run Time Environ ment and exist specifically for use by Pascal programs which will execute under RMX 80 MESSAGE Manipulation Procedures rqsetit m l t Sets the value of the LENGTH field of MESSAGE m to 1 and the value of the TYPE field of m to t Both 1 and t must be integer expressions rqgetlt m l t Sets the value of 1 to the contents of the LENGTH field of MESSAGE m and sets the value of t to the contents of the TYPE field of m Both 1 and m must be variables of type integer RMX 80 Nucleus Operations In RMX 80 PASCAL there is a predeclared procedure or functi
74. emainder of this manual as PASCAL User Manual Since PASCAL User Manual is a concise reference for the features of Standard Pascal the programming language PASCAL 80 will be described only by its differences from and extensions to Standard Pascal the assumption being that the reader 1s familiar with the contents of PASCAL User Manual and moderately conversant with Standard Pascal System Structure As mentioned the PASCAL 80 Run Time System is an interpreter which executes P Code generated by the PASCAL 80 compiler A detailed description of the struc ture of the P Code can be found in Appendix I PASCAL 80 programs can be partitioned into SEGMENT overlay procedures and therefore very large programs may be executed This powerful PASCAL 80 extension is described in Chapter 2 The PASCAL 80 System incorporates a powerful program tracing facility which allows the programmer to selectively monitor the execution of a Pascal program and to interrupt execution at any point PASCAL 80 allows a user error procedure to be specified so that a program may retain control in the event of a run time error and perform error recovery procedures Program Development Cycle The cycle for development and execution of PASCAL 80 application programs that must be performed by the programmer is as shown in figure 1 1 PASCAL 80 PASCAL 80 Introduction EDITOR The source program is created on diskette with the ISIS I te
75. ent system This software is contained on each of two 2 diskettes single and double density be sure to use the appropriate diskette on your disk hardware The directory listing of each of these diskettes can be found in Appendix K Release Disks Each PASCAL 80 Release Disk contains the software listed below COMP COD PASCAL P80RUN LIB FIG31 PAS PASCAL RES GENOBJ COD P80ISS LIB BUFFER PAS FIG32 PAS P80RAR LIB SEEKEX PAS FIG33 PAS P80EXT LIB ERROR PAS FIG34 PAS P80ISS PLB PEOPLE DAT FIG35 PAS FIG36 PAS FIG37 PAS Initial Steps It is highly recommended that you perform the following steps to get started l Initialize a blank diskette as an ISIS II system diskette using the IDISK command 2 Copy all files from your PASCAL 80 Release Disk onto the ISIS II system diskette to create a PASCAL 80 system diskette that you can load from drive 0 3 If you run out of space on the ISIS II system diskette note that in order to run PASCAL 80 you need only the following files ISIS DIR ISIS MAP ISIS TO ISIS LAB ISIS BIN ISIS CLI 4 1 Operating Instructions 4 For most applications the following files on the ISIS II system diskette are also useful but not required to run PASCAL 80 DIR COPY DELETE RENAME ATTRIB SUBMIT 5 tisa good practice and highly recommended that the files containing PASCAL be write protected Using the ISIS II ATTRIBUTE command change the attributes of the following
76. er 1 Input value 200 Value range error Segment 1 Procedure 3 Instruction 54 Figure 8 1 Use of the errorset Procedure PASCAL 80 arithmetic unary unary relational logical not or and APPENDIX A SUMMARY OF OPERATIONS assignment identity sign inversion addition subtraction multiplication integer division real division modulus equality inequality less than greater than less or equal Or set inclusion greater or equal Or set inclusion set membership negation disjunction conjunction union set difference intersection comment Type of Operand s Result Type any type except file types integer or real integer or real integer integer or reai integer scalar string set or pointer scalar or string scalar or string set scalar or string set first operand is any scalar the second is its set type boolean any settype T any ASCII characters same as operand integer or real integer real integer boolean boolean APPENDIX B PASCAL 80 VOCABULARY The PASCAL 80 language vocabulary consists of basic symbols classified into three categories letters digits and special symbols The special symbols are operators and delimiters as follows Operators lt gt lt gt gt t Delimiters reserved words AND ARRAY BEGIN CASE COMPONENT CONST DI
77. ers that are always fatal The other errors are generally nonfatal unless they are issued by the KCONSOLE system call See Table I and 2 below O Noerror detected Limit of 19 buffers exceeded 2 AFTN does not specify an open file 3 Attempt to open more than six files simultaneously 4 Illegal filename specification 5 Illegal or unrecognized device specification in pathname 6 Attempt to write to a file open for input 7 Operation aborted insufficient disk space 8 Attempt to read from a file open for output 9 No more room in disk directory 10 Pathnames do not specify the same disk 11 Cannot rename file name already in use 12 Attempt to open a file already open 13 Nosuch file 14 Attempt to open for writing or to delete or rename a write protected file 15 Attempt to load into ISIS II area or buffer area 16 Illegal format record 17 Attempt to rename delete a non disk file 18 Unrecognized system call 19 Attempt to seek on a non disk file 20 Attempt to seek backward past beginning of file 21 Attempt to rescan a non lined file 22 Illegal ACCESS parameter to OPEN or access mode impossible for file specified 2 23 No filename specified for a disk file 24 Disk error see below 25 Incorrect specification of echo file to OPEN 26 Incorrect SWID parameter in ATTRIB system call 27 Incorrect MODE parameter in SEEK system call 28 Null file extension 29 End of file on console input 30 Drive not ready 3
78. erted in the source code and have the following form directive directive or directivel directive Many of the directives have the form directive or directive Ifa or is not present is assumed The use of embedded directives is discussed below C This directive causes the text following the C to be placed in the code file This is useful for putting copyright information and other text into the code file This directive must appear at the top of the program otherwise a compile time error will occur Example C Copyright 1979 Intel Corp would cause the copyright message to be written to the code file When this directive is followed by a or the I O checking is affected as follows t Causes the compiler to generate code after each statement which performs any I O in order to check whether the 1 O operation was accomplished successfully In the case of an unsuccessful I O operation a run time error will occur I is the default value i Causes the compiler to generate code with no I O checking If an I O error does occur a run time error will not occur When this directive is not followed by a or the directive is interpreted as the INCLUDE FILE directive PASCAL 80 Summary of Compiler Directives e Example I filename will cause the compiler to temporarily suspend its processing of the original source file and to take subsequent source statements from fi
79. external module a Pascal program must be able to specify what variables procedures and or functions are in fact external to the compilation PASCAL COMP F1 SIX1 PAM CODE F1 SIX1 COM COMP F1 SIX1 PAl CODE F1l SIX1 COl COMP F1 SIX1 PA2 CODE F1 SIX1 C02 BUTS SEIPISIKI COM zEI SIXI COI 4FI SIX1 CO2 TO F1 SIX1 COD IT Figure 6 2 Compiling and Joining a Partitioned Pascal Program PASCAL 80 Separate Compilation Program Linkage Relocation and Execution Pascal program may manipulate them as if they were normal i e non external objects Second the specifications cause external references to be generated so that the LINK utility may combine the external modules with the Pascal program o These specifications serve two purposes First they declare the objects so that the A PASCAL 80 program declares external variables procedures and functions in a Public Declaration Record The syntax of a public declaration record is as follows public declaration record PUBLIC lt name gt lt constant deciaration part gt lt type declaration part gt lt variable deciaration part gt lt procedure and function heading part gt END An example of a public declaration record is public asum e type range 0 1000 var aresult integer function asum a b c range integer end All of the items defined in a public declaration record are defined in the global environment of the Pascal program The onl
80. file See figure 3 1 for an example close f Closes the file associated with f and removes that association See figure 3 1 for an example put f Writes the value of the buffer variable ff to the file at the current file position and advances the position to the next component The procedure put f is defined only for typed files See figure 3 for an example get f Assigns the value of the current component of the file f to the buffer variable ft and advances the file pointers to point to the next component If no current component exists eof f becomes true and the value of ft is undefined The function eof f must be false upon entry and f must be a typed file See figures 3 1 and 3 2 for examples CHAPTER 3 PREDECLARED PROCEDUI PROCEDURES 3 Predeclared Procedures PASCAL 80 This program illustrates the use of the predeclared procedures reset rewrite get put and close program threel var 1 integer datafile file of integer begin 3 1 rewrite datafile F1 DDATA DAT create DDATA DAT on drive 1 for i 0 to 10 do write 0 10 onto the file begin datafile i put datafile end reset datafile repeat writeln datafile 5 get datafile until eof datafile close datafile and then close the file end 3 1 re position file to beginning read in and display the integers ng Executing this program will result in the following output Q A 0D J
81. files to W1 PASCAL PASCAL RES and COMP COD Procedures for performing these functions are given in the SIS II User s Guide Order Number 9800306 Compiler The PASCAL 80 Compiler is overlaid and loads its overlays from the drive contain ing COMP COD Run Time System The RTS executes the intermediate code output from the compiler Its code is con tained in the files PASCAL and PASCAL RES Libraries P80RUN LIB P80ISS LIB and PSORAR LIB are ISIS II object module libraries used in the generation of Load and Go versions of a Pascal program They are discussed more fully in Chapter 6 Example Programs EX PAS BUFFER PAS ERROR PAS and SEEKEX PAS are simple demonstra tion programs supplied in source form which show many of the facilities present in PASCAL 80 and which can also be used by the newcomer to familiarize himself with the system SEEKEX PAS is somewhat more complex than the other programs Figure Programs Each one of the example programs in Chapter 3 is supplied in source form so that they may be compiled and executed by the user These files are named FIG3n PAS where n is a digit from 1 to 7 Run Time System Memory Layout The PASCAL 80 Run Time System is composed of an interpreter and a number of predeclared procedures and functions written in Pascal During interpreter execu tion there are two major dynamic data structures the STACK and the HEAP The STACK contains all P code and data frames all
82. g of the program in question the cause of the error may be ascertained When a run time error occurs the display on the screen will be as follows error message Segment S Procedure p Instruction lt i gt where lt s gt lt p gt and lt i gt are integers and lt error message gt is one of the following Stack overflow 4 Value range error 1 Exit from uncalled procedure 3 Integer overflow 5 String overflow 13 Divide by zero 6 NIL pointer reference 7 System I O error 10 Floating point error 12 Unimplemented instruction 11 Program interrupted by user Interrupt 3 8 ISIS II Error lt e gt where e denotes an ISIS II error number where the number following each message is the number of the error E 1 APPENDIX F ISIS II ERROR MESSAGES This appendix lists the error messages issued by the various ISIS II commands The numbered messages are listed in the first section The unnumbered messages that are issued by specific commands are listed in subsequent sections Numbered ISIS II Error Messages By convention error numbers 1 99 inclusive are reserved for errors that originate in or are detected by the resident routines of ISIS II error numbers 100 199 inclusive are reserved for user programs and numbers 200 255 inclusive are used for errors that may be encountered by nonresident system routines In the following list an asterisk precedes error numb
83. gt scan l e a integer seek f lt integer gt setpointer p v sizeof v integer systemcall o a The following predeclared procedures and functions are extensions to PASCAL 80 specifically for RMX 80 applications rqacpt mp e rqctck rqctsk s racxch e H 1 Summary of Extensions to Standard PASCAL H 2 rqdivi 1 rqdtsk t rqdxch e integer rqelvl 1 rqendi rqgetit m 1 t rqisnd i rqresm t rqsend e m rqsetit m 1 t rqsetp a 1 rasetv a 1 rqsusp t rqwait mp e t PASCAL 80 APPENDIX I IMPLEMENTATION DETAILS Data Type Formats Every variable in PASCAL 80 is aligned on an even byte or word boundary although individual elements of a PACKED structure may occupy as little as one bit n a PACKED ARRAY OF boolean All interpreter operations expect their operands to occupy at least one word even if not all of the information in that word is valid boolean One word with bit O indicating the value false 0 true 1 The other bits are ignored by the boolean operations char One word with the low byte containing the character The high order byte is ignored by operations using a value of type char integer One word The value is stored in two s complement form so that a variable of type integer can assume values in the range 32768 32767 scalar One word with value in the range 0 32767 real Two words in INTEL floating point format POINTER One w
84. guage PASCAL 80 con tains a number of predeclared procedures and functions These include the standard procedures as defined in the PASCAL User Manual plus additional procedures which are extensions to Standard Pascal These predeclared procedures and func tions are declared in the Run Time Environment surrounding each Pascal program and may be redeclared with no conflict The predeclared procedures and functions include generally useful utility routines data structure access routines and routines designed to allow PASCAL 80 pro grams access to the powerful system features of ISIS IJ The following discussion assumes that the reader is familiar with the characteristics of ISIS II as described in the Intel publication SIS II User s Guide Publication Number 9800306 File Manipulation Procedures reset f Resets the current file position to the beginning of the file f and positions the file pointers to the first record in the file If f is not an INTERACTIVE file a get f is performed The function eof f becomes true if f is empty otherwise eof f becomes false See figures 3 1 and 3 3 for examples reset f lt string gt Opens an existing ISIS H file with the name lt string gt associates f with that file and then performs reset f See figure 3 2 for an example rewrite f lt string gt Creates an ISIS II file with the name lt string gt associates f with that rile and sets the file pointers to the beginning of the
85. gure an RMX 80 Application System which includes a Pascal task a number of the configuration parameters must have specific values These parameters with their values are described below Any configuration parameter which is not mentioned in the following list is not constrained by RMX 80 PASCAL it may assume any valid value consistent with the structure of the application system 7 7 Preparing Programs to Run Under RMX 80 PASCAL 80 The values of the following configuration parameters are constrained as follows TERM HNDLR lf the Pascal program references either of the predeclared files input or out put or performs I O to either CI or CO one of the versions of the Ter minal Handler must be specified TASK NAME You may use any name for your Pascal task ENTRY POINT The ENTRY POINT must be specified as P8INIT STK LENGTH This parameter should be set to the value 2 since the Pascal task defines its own work space and STACK DFLT EXCHG The Pascal task does not use a Default Exchange EXTRA This parameter is set to 0 DFS The Disk File System must be included if the Pascal program accesses any disk files ATTRIB DELETE FORMAT LOAD RENAME DISKIO These DFS services are included only if the Pascal program calls them explicitly OPEN CLOSE READ WRITE SEEK These must be included if the DFS is specified LINK The following files must be included in the LINK list in the following order lt
86. irth date MONTH get date birth writeln write Number of dependents readln input dependents write Amount of money owed readln input debts repeat write Marital Status M arried S ingle write D ivorced W idowed readln input ch case ch of M m begin marital status married write Input date married MONTH get date date married end S s begin marital status single independent true end D d s begin marital status divorced first divorse true write Input date divorced get date date divorsed end W w begin marital status widowed write Input date married get date date married end end case until ch n T M m s s D utg w allocated true put people writeln end end with until eof input or only_one if not only one then close people lock end initfile function display a record integer boolean procedure print date date to print date begin with date to print do begin writeln ord month 1 0 day 0 year 0 end with end print date begin display Seek people a record get people with people name do begin if eof people or not allocated then begin display false exit display end display true writeln writeln writeln first last case sex of male writeln Male female writeln Female end case writeln Social securit
87. ison not allowed Illegal type of operand s Type of operand must be boolean Set element type must be scalar or subrange Set element types must be compatible Type of variable is not array Index type is not compatible with the declaration Type of variable is not record Type of variable must be file or pointer Illegal parameter solution Illegal type of loop contro variable Illegal type of expression Type conflict Assignment of files not allowed Label type incompatible with selecting expression Subrange bounds must be scalar Index type must be integer Assignment to standard function is not allowed Assignment to formal function is not allowed No such field in this record Type error in read Actual parameter must be a variable Control variable cannot be formal or non local Multidefined case label Too many cases in case statement No such variant in this record Real or string tagfields not allowed Previous declaration was not forward Again forward declared Parameter size must be constant Missing variant in declaration Substitution of standard proc func not allowed Multidefined label Multideclared label Undeclared label Undefined label Error in base set Value parameter expected Standard file was redeclared Undeclared external file Pascal function or procedure expected Previous declaration was segment declaration Separate declaration valid only on global level Separate procedure must be a segment Comment or he
88. ite f vj where writeln f writes an end of line character of the file f See figures 3 2 and 3 3 for examples page f Causes a form feed character to be written to the TEXT or INTERACTIVE file f w ER length b buffers s from to i yn veni will be entered expt cio 255 is specified ical ine The values gor PASCAL 80 Predeclared Procedures eoln f boolean Returns true if the TEXT or INTERACTIVE file f is positioned at an end of line ENANA ci n ERE returns false loresult integer Returns the error code of the last V O operation If no error was detected the value is 0 T M a Dynamic Allocation Procedures new p Allocates a new variable t and assigns the address of t to the pointer variable p where p is defined as VARp t If the type of t is a record type with variants new p allocates a storage area large enough to accommodate the largest variant See figure 3 4 for an example new p t1 tj Allocates a variable of the uic is size for the variant with tag field values equal to the constants t1 tj and assigns the address of that variable to the pointer variable p mark p Assigns the address of the current top of the HEAP to the pointer variable p see MENS 3 4 or an Fan tius Sets the top of the HEAP to the value of the pointer variable p See figure 3 a for an EEE Returns the arithmetd ditference Be ie current bottom of ike execu tion sta
89. ith corrected code to fix the problem or 3 Issue a notice of availability of a new revision with corrected code Copyright 1979 1980 Intel Corporation Intel Corporation 3065 Bowers Avenue Santa Clara California 95051 Additional copies of this manual or other Intel literature may be obtained from Literature Department Intel Corporation 3065 Bowers Avenue Santa Clara CA 95051 The information in this document is subject to change without notice Intel Corporation makes no warranty of any kind with regard to this material including but not limited to the implied warranties of merchantability and fitness for a particular purpose Intel Corporation assumes no responsibility for any errors that may appear in this document Intel Corporation makes no commitment to update nor to keep current the information contained in this document Intel Corporation assumes no responsibility for the use of any circuitry other than circuitry embodied in an Intel product No other circuit patent licenses are implied Intel software products are copyrighted by and shall remain the property of Intel Corporation Use duplication or disclosure is subject to restrictions stated in Intel s software license or as defined in ASPR 1 104 9 a 9 No part of this document may be copied or reproduced in any form or by any means without the prior written consent of Intel Corporation The following are trademarks of Intel Corporation and may be used only to
90. l not generate any type of automatic sign on message CHAPTER 7 PREPARING PROGRAMS TO RUN UNDER RMX 80 This chapter describes the use of the special facilities provided to support Pascal programs in the RMX 80 run time environment specifically the PASCAL 80 Run Time Package for RMX 80 Systems iSBC803 Use of RMX 80 itself is described only to the extent necessary to explain how to interface PASCAL 80 pro grams with it for complete instructions refer to the RMX 80 User s Guide All of Chapter 7 exceeds standard Pascal gt Also described in this chapter is the use of the RMX 80 Interactive Configuration utility ICU80 in configuring a Pascal based RMX 80 application system The ICU80 utility automates the configuration linking and locating operations described in the RMX 80 User s Guide It generates the configuration object module the controller addressable memory CAM module and a submit file con taining the link and locate commands required to build the RMX 80 application system For a complete description of this utility refer to the RMX 80 Interactive o Configuration Utility User s Guide A PASCAL 80 program executing in the RMX 80 environment can avail itself of all of the features of an ISIS II Pascal program including the external linking capabilities described in Chapter 6 Additionally RMX 80 PASCAL contains language extensions which facilitate the incorporation of a Pascal program as a task in the RM
91. lename The compiler will continue to process lt filename gt until it reaches its end of file at which point the compiler will resume processing the original source file If a drive number is specified 1 e F1 filename the file will be opened on the specified drive otherwise the file is opened on the same drive from which the original source was taken Since all the characters between the I and the or are taken to be the file name no other directives can follow the include file directive until that directive is closed by a or An include file may be specified anywhere in the original source file The text in the included file merely replaces the INCLUDE directive and becomes part of the source program The resulting program must of course be syntactically and semantically correct or else a compile time error will occur However in order to allow for con venient structuring of INCLUDEd source code PASCAL 80 relaxes the rules con o cerning the ordering of declarations Under these relaxed rules if a file is included just after a program s or procedure s last data declaration just before the start of the code statements it may contain within itself a complete set of CONST TYPE and VAR declarations as well as PROCEDURE and FUNCTION declarations An include file cannot contain an include file directive If this occurs a compile time error is generated R This directive affects the RANGE CHECKING of the compiler
92. lustrates the use of the predeclared procedures ord and chr program three5 type colors red green yellow blue begin writeln ord red 3 ord green 3 ord yellow 3 ord blue 3 w writeln chr ord A fend 3 5 Executing this program will result in the following output Oo cd X9 A Figure 3 5 Examples of Predeclared Procedures ord and chr 3 7 Predeclared Procedures PASCAL 80 This program illustrates the use of the predeclared procedure exit program three5 var i integer procedure alpha forward procedure beta forward procedure gamma forward procedure alpha begin beta writeln Exit alpha end alpha procedure beta begin gamma writeln Exit beta end beta procedure gamma begin write Please enter a digit readln i writeln writeln Thank you case i of 1 exit three6 2 exit alpha 3 exit beta 4 exit gamma end case writeln Exit gamma end gamma jg begin alpha writeln Exit program end 3 6 Executing this program will Sequences depending upon result in the following output the value of lt n gt Please enter a digit lt n gt lt n gt is entered by the user Thank you Thank you Thank you Thank you Thank you Exit program Exit alpha Exit beta Exit gamma Exit program Exit alpha Exit beta Exit program Exit alpha Exit program lt n gt 1 lt n gt 2 lt n gt
93. me is 16383 words Differences Between PASCAL 80 and Standard Pascal In PASCAL 80 the goto statement may only reference local labels i e labels declared in the same block as the goto statement itself A goto statement may not reference a label declared in an enclosing block as is possible in Standard Pascal However the predeclared procedure exit overcomes this limitation and provides even more capabilities PASCAL 80 does not support the standard procedures pack and unpack as described in the PASCAL User Manual PASCAL 80 limits the enumerated elements of a set to positive values only PASCAL 80 does not support the construct in which PROCEDURES and FUNC TIONs may be declared as parameters of a PROCEDURE or FUNCTION PASCAL 80 does not support the predeclared procedure dispose However the pro cedures mark and release can be used to approximate the actions of dispose PASCAL 80 APPENDIX J PASCAL REFERENCE TEXTS The primary reference text for Pascal 80 the source which defines Standard Pascal is PASCAL User Manual and Report Kathleen Jensen and Niklaus Wirth Springer Verlag New York 9 1974 Corrected Printing 1978 In addition the following texts should be investigated by anyone interested in programming in Pascal Algorithms Data Structures Programs Niklaus Wirth Prentice Hall 1976 A Practical Introduction to Pascal I R Wilson amp A M Addyman Springler Verlag New
94. ment will be displayed when a user program is next executed The fourth command turns off the TRACE flag while the fifth command returns control to 1SIS 11 Code Filename Specification A code filename may be expressed in the following ways Name Typed Name Used lt filename gt lt ext gt lt filename gt lt ext gt filename lt filename gt COD filename filename PASCAL 80 PASCAL 80 Operating Instructions e Command Line Options When the command line specifies a Pascal code file to be executed that code filename may be followed by an arbitrary lt options gt field This lt options gt field specifies run time parameters to the program being invoked and may be input by that program using the standard read and readln procedures When a program starts executing the function eoln input will reflect the presence of an lt options gt field It will be false 1f options are present and true otherwise The following Pascal statements can be used to collect the options from the com mand line if any and place them in the string variable options if eoln input then options else readin input options The program may then inspect the value of options and perform the appropriate actions Program Tracing Facility The PASCAL 80 System incorporates a program tracing facility which allows for selectively monitoring the execution of a Pascal progr
95. more detail Data Types Every variable appearing in a Pascal program must be associated with one and only one data type The following data types are predeclared in the PASCAL 80 System using the type declaration facility new data types of arbitrary complexity may be defined In the following discussion a word is defined to be a two byte quantity aligned on an even byte boundary PASCAL 80 Language Features The Boolean Type A variable of type boolean can have one of the values denoted by the predefined identifiers false and true The definition of the type is TYPE boolean false true It should be noted that under this definition false lt true A variable of type boolean requires two bytes of storage although only the least significant bit is significant The Integer Type The standard type integer is defined to be a subrange of whole numbers In PASCAL 80 its definition is TYPE integer 32768 32767 There also exists a predefined standard variable of type integer named maxint which has the value 32767 A variable of type integer occupies two bytes of storage The Real Type Variables of type real have values which are elements of a subset of real numbers In PASCAL 80 a value r of type real will satisfy the following 1 17 10E 38 lt r lt 3 40 10E38 approximately or 3 40 10E38 lt r lt 1 17 10E 38 approximately Further information concerning the characteristics of
96. nal references in the program will be automatically linked to the associated external object For example if the command SIX3 Is now given to the PASCAL 80 Command Line Interpreter the example program in figure 6 3 will be executed and will access the specified external functions and variables Load and Go Program Generation In all the discussions up to now the only way to execute a PASCAL 80 program was to first invoke the Pascal Run Time System and then the desired program While this two step process is valuable during program development it may be a bit cumbersome for a fully debugged production program To allow for this latter situation it is possible to construct a Load and Go version of a Pascal program This Load and Go version is invoked directly from the ISIS II command line inter preter does not automatically display any sign on or start up message and thus presents a simpler more standard interface to the user Generating the Relocatable Object Module The PASCAL 80 compiler produces a code file which is in a format appropriate for execution by the Pascal Run Time System However this format is not compatible with the relocatable object file format so the code file must be transformed into a relocatable object file with the GENOBJ utility This utility is invoked by the command GENOB J lt code file gt TO lt obj file gt FREE lt size gt where the FREE control specifies the initial size of the free space
97. nce in environments This characteristic allows many RMX 80 PASCAL tasks to be thoroughly tested in the ISIS II environment before being executed under RMX 80 In PASCAL 80 procedure and function parameters can be passed by value value parameters or by reference variable or var parameters Also as described in Chapter 6 a Pascal program can establish linkages with external procedures func tions and data structures These capabilities together with PASCAL 80 extensions described in later sections allow a Pascal program complete access to all of the facilities of RMX 80 7 1 Preparing Programs to Run Under RMX 80 7 2 Initialization and Termination Every PASCAL 80 program exists within a surrounding Run Time Environment This surrounding environment contains the predeclared procedures and functions described in Chapter 3 and elsewhere a number of predeclared data identifiers and the code required to perform all necessary global initialization and termination sequences The nature of these sequences depends upon the execution environment of the Pascal program but in all cases is sufficient to correctly execute the program In particular it is not necessary within the RMX 80 environment for tasks separate from the main Pascal task to invoke any special initialization for termina tion routines the Run Time Environment within the Pascal task contains all of these routines When a Pascal program terminates executing unde
98. nd release sin x real cos x real log x real exp x real In x real sqrt x real arctan x real These functions ali require x to be either integer or real and all return a result of type real trunc x integer Returns the whole part of the real argument x The fractional part is discarded so that trunc 5 78 5 and trunc 2 9 2 round x integer Returns the rounded integer of the real argument x This function is defined as follows round x trunc x 0 5 if x gt 0 round x trunc x 0 5 if x lt 0 3 6 PASCAL 80 Predeclared Procedures pwroften x real Returns 10 raised to the xth power where x is an integer such that O lt x lt 38 Predicates odd x boolean Returns true if x is an odd integer otherwise returns false x must be of type integer Transfer Functions ord x integer Returns the ordinal number of the value of x in the set defined by the type e of x Note that x must be of a scalar type See figure 3 5 for an example chr x char Returns the character whose ordinal number is the value of x if it exists x must be of integer type See figure 3 5 for an example Miscellaneous Routines succ x type of x Returns the successor value of x if it exists x must be of a scalar or subrange type pred x type of x Returns the predecessor value of x if it exists x must be of a scalar or subrange type This program il
99. nerating the Relocatable Object Module 6 12 Linking the Object Module 6 13 Locating the Object Module 6 13 Program Execution een 6 13 CHAPTER 7 PREPARING PROGRAMS TO RUN UNDER RMX 80 Program Structure Under RMX 80 7 1 Initialization and Termination 7 2 laputand OUtplb issues ERES Sa Ev D s 7 2 File Name Format oo ee 7 2 The Predeclared Files Input and Output PI 7 3 DFS Service Operations 0 00 cece cece eee 7 3 Run Time Error Handling 7 3 PASCAL 80 Extensions for RMX 80 7 3 Need for RMX 80 Extensions 7 4 The MESSAGE Data Type 7 4 Predeclared Procedures and Functions for RMX 80 o o ooo o 7 5 MESSAGE Manipulation Procedures 7 5 RMX 80 Nucleus Operations 7 5 Constructing an RMX 80 System 7 7 Generating the Relocatable Object Module 7 7 The Interactive Configuration Utility 7 7 CHAPTER 8 RUN TIME ERROR PROCEDURES APPENDIX A SUMMARY OF OPERATIONS viii APPENDIX B PASCAL 80 VOCABULARY APPENDIX C SUMMARY OF COMPILER DIRECTIVES APPENDIX D COMPILER ERROR MESSAGES APPENDIX E RUN TIME ERROR MESSAGES APPENDIX F ISIS II ERROR MESSAGES APPENDIX G SYNTAX SUMMARY APPENDIX H SUMMARY OF EXTENSIONS TO STANDARD PASCAL APPENDIX I IMPLEMENTATION DETAILS APPENDIX J PASCAL REF
100. nstant identifier Examples of constant declarations are CONST maxfiles 6 CONST version PASCAL 80 V1 0 nfiles maxfiles Type Declaration Part The type declaration part is a mechanism for creating new data types The declara tion determines a set of values for the new type and associates an identifier with that set The general form for this declaration is TYPE identifier type identifier type Examples of type declarations are TYPE weekdays monday tuesday wednesday thursday friday TYPE filenumber 1 nfiles filetype source object Variable Declaration Part Every variable used in a program statement must first be declared in the variable declaration part This declaration associates both an identifier and a data type with the variable being declared The general form of this declaration is VAR identifier lt identifier gt type identifier identifier type Examples of variable declarations are VAR alpha beta gamma integer VAR name string 30 Procedure and Function Declaration Part Every procedure and function must be defined before its use A procedure declara tion associates an identifier with a set of actions which may then be invoked by referring to the identifier Functions are similar to procedures but also yield a result value and therefore can be referred to within expressions Procedure and functions are discussed below in
101. ntheses The default value is all space ETAB external file name Specifies the external table file when compiling a Pascal program with exter nal references The default is lt source filename gt ERT NOSTATISTICS Specifies that the compiler should not accumulate or list the procedure data frame and parameter sizes Excluded Combinations Certain of these directives may not be used in combinations The following table shows which directives are excluded if the directive in the left hand column is specified Excluded Directives NOLIST LIST ERRLIST NOCODE CODE Summary of Information on CRT The general format of the basic command line is COMP filename directives The compiler will reply with PASCAL 80 Compiler Vv r Where v is the version number and r is the release number Each directive is then acknowledged by the compiler on a separate line and is either ACCEPTED or REJECTED After all the directives have been acknowledged and none were rejected the compiler opens its files and starts to compile If any directive was rejected it will display Compilation Terminated and control is returned to the PASCAL 80 System Operating Instructions Operating Instructions PASCAL 80 If all directives were accepted it will display the message COMPILING filename If any file fails to open correctly the compiler will display filename failed to open The compilation will be terminated returning
102. number 8 Record value 8 Record number 7 Record value 7 Record number 6 Record value 6 Figure 3 2 Examples of Predeclared Procedures reset seek and get This program illustrates the use of the predeclared procedures read and readin program three3 var DIC char datafile text begin 3 3 rewrite datafile Fl TDATA DAT create a temporary file on drive 1 writeln datafile AB write a two character line writeln datafile YZ and a two character line reset datafile re position file to the beginning a 1 initialize variables b 2 oo sa tts gt 9t read datafile a b c y z c since at end of line writeln a b c y 2 display the values reset datafile d b 2 s c 130 g imo 59734 readin datafile a read the A skip to the next line readin datafile y read the Y and skip to eof writeln a b c y 2 close datafile end 3 3 Executing this program will result in the following output AB YZ A23Y9 Figure 3 3 Examples of Predeclared Procedures read and readIn Predeclared Procedures PASCAL 80 write f v1 vj This procedure may be used only with TEXT or INTERACTIVE files If f is omitted output is assumed Note that this construct is equivalent to write f v1 write f vj See figures 3 2 and 3 3 for examples writeln f vl vj This construct is equivalent to the sequence write f v1 wr
103. o range check ing is performed so they should be used with some care Mec ita ONE d which must be of the form ET E rs t a ica where character expression is an expression which evaluates to a character value M ai ARRAY a m y be subscripted to denote a starting 1 a scanned i is o If the first character satisfies the partial ex pression gt 0 is returned if no character is satisfactory length is return ed If lt length gt is negative the array is scanned backwards and the value returned will be lt 0 See figure 3 8 for an example PASCAL 80 Predeclared Procedures to denote a duris postion other an the first Sharacier The novel routine starts at the specified left end of both arrays and copies moving right The moveright routine starts at the right end of both pS and copies bytes moving left See figure 3 8 for an example fillchar a lt length gt lt character gt Fills the ARRAY a with lt length gt lt character gt s The ARRAY may be subscripted to denote a starting position other than the first character See figure 3 8 for an example This program illustrates the use of the character array routines scan moveleft moveright and fillchar program three8 var ca cb packed array 0 9 of char sa string 30 begin ca 0123456789 writeln scan 10 z 4 ca 3 scan 10 4 ca 2 4 writeln scan 10 X ca 3 scan 5 X ca 4 writeln sc
104. on corresponding to each RMX 80 Nucleus operation The names of these Pascal routines are iden tical to their RMX 80 counterparts as are the order and type of their parameters E rqsend e m Sends the MESSAGE m to the exchange e rqwait mp e t sion and returns the address of a message in mp which must be a pointer to e Waits at exchange e for a time limit of t which must be an integer expres a MESSAGE 7 5 Preparing Programs to Run Under RMX 80 PASCAL 80 7 6 rqacpt mp e Returns the address of a message which has been sent to the exchange e If no message is there NIL is returned The address or NIL is placed in mp which must be a pointer to a MESSAGE rqctck Decrements the time counters on all tasks on the Delay list rqctsk s Creates a task given the Static Task Descriptor s rqcxch e Initializes the exchange e rqdivi l Disables the interrupt level given by I which must be an integer expression rqdtsk t Deletes the task described by the task descriptor t rqdxch e integer Deletes the exchange e rgelvi l Enables the interrupt level given by l which must be an integer expression rqendi Ends the interrupt in a user supplied interrupt routine rgisnd i Sends a message to the interrupt exchange i rqresm t Resumes a suspended task described by the task descriptor t rqsetp a l Associates the address a of a user supplied interrupt procedure with an interrupt level The procedure cannot be a Pascal
105. ord with a value in the range 0 65535 SET 0 255 words depending upon the number of elements in the set Sets are stored as bit vectors with a lower index of zero where each bit corresponds to a possible set element A set variable declared as SET OF a b is allocated b 15 div16 words all of which contain valid information All elements past the last word of a set are assumed to not be elements of the set RECORDs and ARRAYs Any number of words depending upon the size of the structure Arrays are stored in row major order When a record or an array is an operand to a procedure or internal operation the structure itself is never loaded onto the stack just a reference pointer to it Implementation Details string 1 128 words depending upon the declared maximum length of the string A variable declared as s string n is allocated n div 2 1 words The first byte of the string s 0 contains the current valid length of the string while the bytes 1 s 0 contain the valid characters Implementation Size Limits e The maximum number of characters in a variable of type string is 255 e The maximum number of elements in a set is 255 16 4080 e The maximum number of PROCEDUREs or FUNCTIONS in a segment is 127 e The maximum number of user SEGMENT PROCEDURE and SEGMENT FUNCTIONS is 7 e The maximum number of bytes of object code in a PROCEDURE or FUNCTION is 1200 e Themaximum size of a data fra
106. pendix K Directory of Release Diskettes which lists the file directories of both the s ngle density and double density release diskettes Related Publications For additional information concerning ISIS II and PASCAL 80 refer to the follow ing Intel documents ISIS II User s Guide Order Number 9800306 8080 8085 Floating Point Arithmetic Library User s Manual Order Number 9800452 ISIS II CREDIT CRT Based Text Editor User s Guide Order Number 9800902 RMX 80 User s Guide Order Number 9800522 RMX 80 Interactive Configuration Utility User s Guide Order Number 142603 PL M Programming Manual Order Number 9800268 ISIS II PL M Compiler Operator s Manual Order Number 9800300 8080 8085 Assembly Language Reference Manual Order Number 9800301 o ISIS II 8080 8085 Macro Assembler Operator s Manual Order Number 9800292 FORTRAN 80 Programming Manual Order Number 9800481 ISIS II FORTRAN 80 Compiler Operator s Manual Order Number 9800480 Notation in this Manual Throughout this manual the following notation is used to describe the format of a Pascal program gt I Certain key words are reserved and cannot be used as identifiers In this manual they are in capital letters Refer to Appendix B for a list of reserved words 2 Variable names are denoted by words in lower case 3 Language features which exceed Standard Pascal are shaded CHAPTER I INTRODUCTION PAGE General Desc
107. procedure Used for iSBC 80 10 applications rqsetv a l Associates the address a of a user supplied interrupt procedure with an interrupt level The procedure cannot be a Pascal procedure Used for non ISBC 80 10 applications rqsusp t Suspends the task described by the task descriptor t PASCAL 80 Preparing Programs to Run Under RMX 80 Constructing an RMX 80 System The construction of an RMX 80 applications system which contains a Pascal task can be partitioned into four major steps e Generating the relocatable object modules of any non Pascal tasks e Generating the relocatable object module of the Pascal task e Invoking the RMX 80 Interactive Configuration Utility ICU80 to produce the various configuration object modules and the associated Command Sequence Definition file e Applying the SUBMIT command to the Command Sequence Definition file generated in the above step to link and locate the complete RM X 80 application system Since a discussion of the first step above is dependent upon the specific application system being constructed we will assume any such modules have been compiled assembled and linked Refer to the Intel manuals cited in the Preface for instructions about utilizing other languages Generating the Relocatable Object Module The procedure for generating the relocatable object module of a Pascal task is essen tially identical to that for constructing the relocatable o
108. r ISIS II the Run Time Environ ment causes all open files to be closed and then transfers control to the ISIS II Com mand Line Interpreter The termination logic in the Run Time Environment of a Pascal task under RMX 80 also closes all open files but then causes the task to sus pend itself forever by waiting for a message at an empty private exchange This means that if you want your Pascal task to be active at all times it should be coded as a repeat statement or a while statement such that the exit condition is never satisfied If some such statement structure is not utilized and the program executes its last statement or an exit lt program name gt statement is executed the Pascal task will be suspended forever the only way to revive it is to activate the hardware reset feature which will cause it to be reinitialized Input and Output The RMX 80 PASCAL run time input output support library P8SORMX LIB allows you to invoke the standard predeclared Pascal procedures and functions RESET REWRITE CLOSE PUT GET SEEK READ WRITE BUFFERREAD BUFFERWRITE BLOCKREAD BLOCKWRITE EOF EOLN and IORESULT for input and output to the Terminal Handler and Disk File System DFS No sending of request messages to the Terminal Handler or Disk File System is required this is all done by the routines in PBORMX LIB File Name Format In ISIS 1I filenames and extensions are defined by the user but device names are preestablished by the
109. r encounters this directive it will not issue tracing instructions in any subsequent code which is 4 5 Operating Instructions 4 6 generated This situation will persist until a T directive is encountered at which time tracing instructions will begin to be generated again Therefore using these directives an entire Pascal program or just selected portions may contain tracing instructions Run Time Monitoring The PASCAL 80 Run Time System has the capability to continuously monitor the dynamic sizes of both the STACK and the HEAP Since a performance degradation occurs when this monitoring is in effect the user is able to turn it on and off with the SIZEON and SIZEOFF commands When size monitoring is in effect the system keeps track of three values as they are varied by the running user program e The maximum size of the STACK at any time e The maximum size of the HEAP at any time e The maximum combined size of the STACK and HEAP at any time These values are initialized to zero when a program commences execution and are saved when it returns to the Pascal Command Line Interpreter The STACK size value does not include the space consumed by the resident code of the Pascal pro gram but does include the space occupied by each data frame including the pro gram s global data frame and also the length of any SEGMENT procedures The STATS command will display these saved values They are useful when generating a Load an
110. real values in PASCAL 80 can be obtained by consulting the Intel publication 6080 8085 Floating Point Arithmetic Library User s Manual Publication Number 9800452 A variable of type real occupies four bytes of storage The Char Type A variable of type char has values which are elements of the finite set of characters In PASCAL 80 this set of values can be defined by TYPE char chr 0 chr 255 The ASCII control and graphic coding is employed and therefore so is the ASCII collating sequence A variable of type char occupies two bytes of storage although the most significant byte is always zero The ARRAY Type A variable of type ARRAY has values which are composed of a fixed number of components each one of which is of the same type called the base type In PASCAL 80 the ARRAY type is as specified in Standard Pascal 2 3 Language Features If the ARRAY declaration is prefixed by the reserved word PACKED the compiler will attempt to minimize storage requirements by packing more than one component into each word However this packing is subject to the following restrictions Packing will never cross word boundaries This implies that an array will be packed only if any value of the base type can be represented in one byte or less such as boolean char or 0 73 Packing densities for various base type representations are as follows Bits to Represent Value Components Word 3 8 9 and up 1 no packing An array
111. ription 2 cece ee eee 1 1 The PASCAL 80 Language ooooooooomomoo 1 2 SYSTEM SUCIO ai REDE IE ORE RIS 1 2 Program Development Cycle 1 2 CHAPTER 2 LANGUAGE FEATURES Program Structure uses v RR FERRE RT URS 2 1 Program Heading 15 uns an 2 1 Label Declaration Part cr E e xa 2 1 Constant Declaration Part 2 2 Type Declaration Part scene rn et 2 2 Variable Declaration Part o 2 2 Procedure and Function Declaration Part 2 2 Data Types bees aba oie oe isn 2 2 The Boolean Type zu ERE ER ERE 2 3 The nteper TI VDO Arster ee 2 3 The Real Lype usar e vA oO dab ees 2 3 The Char Type 5 eR RE EE ERE dene 2 3 The ARRAY Type eee n 2 3 The RECORD Type en ERR CA E ER ehem 2 4 TNE SINS Type unseren eec 2 5 NESE Type uri o aan 2 5 The BIEBAT VDO ace ers 2 5 Ut typed Files ao bag Koc abe ey dei eee 2 6 INTERACTIVE Files ore sa cere isa 2 6 The POINTER Type co ig cis noria 2 6 PROCEDUREs and FUNCTIONS 2 7 SEGEMENT Procedures ooooooooooomoo 2 7 CHAPTER 3 PREDECLARED PROCEDURES File Manipulation Procedures 3 1 File Manipulation Functions o ooooooo o 3 4 Dynamic Allocation Procedures 3 5 Arithmetic Functions ooooooooomm mom 3 5 Predicales 40 tir i Esa faute ar I Te 3 7 Transfer FUNCUONS escarnio 3 7 Miscellaneous Routines
112. s 108 File notallowed here gt 109 Type must not be real 110 lt tagfield gt type must be scalar or subrange 111 Incompatible with lt tagfield gt part 112 Index type must not be real 113 Index type must be a scalar or a subrange 114 Base type must not be real 115 Base type must be a scalar or a subrange 116 Error in type of standard procedure parameter 117 Unsatisfied forward reference 118 Forward reference type identifier in variable declaration 119 Respecified parameters for a forward declared procedure 120 Function result type must be scalar subrange or pointer 121 File value parameter not allowed Compiler Error Messages 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 174 190 191 192 193 201 202 203 A forward declared function s result type can not be respecified Missing result type in function declaration F format for reals only Error in type of standard procedure parameter Number of parameters does not agree with declaration illegal parameter substitution Result type does not agree with declaration Type conflict of operands Expression is not of set type Tests on equality allowed only Strict inclusion not allowed File compar
113. s detected is terminated and the STACK is unwound appropriately In order for a user error procedure to effectively process the run time error condi tion the following predeclared integer variables are present in the Run Time Environment 2 errnumber The number of the last run time error errsegment The segment number when the error occurred errprocedure The procedure number when the error occurred errdisplacement The instruction displacement when the error occurred errsystem The ISIS Il error number if errnumber 10 When a user declared error procedure is invoked the active error procedure specification reverts to the standard default error procedure Therefore after a run time error has occured erroset p must be called again if you still want a user error procedure to be active See figure 8 1 for an example of a user error procedure 8 1 Run Time Error Procedures This program illustrates the use of the errorset procedure program eightl type value 0 255 procedure rterror begin writeln writeln Detection of Error Number errnumber 0 writeln end procedure square i value begin writeln Input value i 0 i 1 i writeln Squared result i 0 writeln end begin errorset rterror square 10 square 100 square 200 end eightl Executing this program results in the following output Input value 10 Squared result 100 Input value 100 Detection of Error Numb
114. s a very powerful high level language which is now gaining wide acceptance as a useful programming tool PASCAL 80 is a Pascal language system designed for the Intel 8080 8085 microcomputers under control of the ISIS II Operating System It is designed to run on a 64K byte Intellec or Series II microcomputer development system plus CRT and floppy diskettes Although a minimum system would include only one single density diskette for maximum efficiency a system with at least two double density diskettes is recommended The PASCAL 80 System is composed of a Run Time System RTS and a compiler which itself executes on the Run Time System The PASCAL 80 compiler converts Pascal source code into an intermediate P Code pseudo code which is then interpreted by the Run Time System The ISIS II text editor is used to create the Pascal source file s The PASCAL 80 compiler is then used to compile the source programs so that they may be executed on the RTS A listing of the PASCAL 80 source program is provided by the compiler during compilation Any error messages are included in this listing Complete operating instructions can be found in Chapter 4 along with a more com plete description of the structure of the PASCAL 80 System Chapter 5 presents four PASCAL 80 example programs including a complex example along with typical user interaction with these programs All example programs are listed in the manual and are also present on the PASCAL 80
115. same type components The type is distinguished from the ARRAY type in that the FILE type has a variable number of components In PASCAL 80 each structure of type FILE must be associated with an ISIS II device or disk file which are discussed in Chapter 2 of the ISIS II User s Guide This association is established by the reset or rewrite procedures described below and is terminated by the close procedure also described below Note that every open file allows for update access 1 e each file is opened with an access mode value of 3 Standard Pascal does not allow a file to be opened for input only or output only As in Standard Pascal the two textfiles input and output are predeclared in the sur rounding environment These files are automatically associated with the ISIS II system console devices CI and CO respectively and do not have to be opened by the Pascal program Untyped Tiles and INTERACTIVE fil files ee es OS 2 to Standard Pase al 2 5 Language Features 2 6 Untyped Files Untyped files were introduced so that a program could perform efficient unstruc tured block transfers to and from memory These transfers are performed with the procedures blockread blockwrite bufferread and bufferwrite The following example program will copy file SSS to file DDD using an 8K memory buffer program fcopy const size 8192 var s d file s and d are untyped files buffer packed array 1 si
116. since the Pascal Run Time System allocates the STACK from its workspace As a check on the relative location of the External Reference Table the PUBLICS option should be invoked in the LOCATE command This option will cause the value of the symbol PQETAB among others to be listed This value should be exactly the same as the base address specified in the locate command Load the External Module into Memory and Invoke the PASCAL 80 Run Time System The located external module EXTMOD can now be loaded into Intellec Memory at its proper address with the DEBUG command DEBUG EXTMOD nnnn The DEBUG command loads the file into memory and invokes the Monitor The b Monitor responds with the starting address of the module which should be ignored The monitor then displays a period and waits for a command to be entered You should respond with G8 followed by a carriage return to return to ISIS II At this point so as not to disturb the external module loaded into the top of memory you must immediately invoke the PASCAL 80 Run Time System with the command PASCAL R o The control causes PASCAL 80 to set the upper boundary of its work space to the value of the PUBLIC symbol PQETAB which is defined to be the base of the exter nal module 6 11 Separate Compilation Program Linkage Relocation and Execution 6 12 The PASCAL 80 Run Time System is now used in the standard way to execute the Pascal program All exter
117. ts function asum a b c 0 1000 integer NAME ASUM PUBLIC ARSLT ASUM Declare the result variable DSEG ARSLT DW 0 f ASUM XCHG Move DE to HL DAD B Add in the second argument POP D Skip over the return address POP B get the third argument DAD B and add it in PUSH D Restore return address SHLD ARSLT RET END No starting address since not a External module to compute the SUM of the three arguments function psum a b c 0 1000 integer PSUMSMODULE DO CSEG Compute the sum of the three arguments DECLARE PRSLT ADDRESS PUBLIC PSUM PROCEDURE A B C ADDRESS PUBLIC DECLARE A B C ADDRESS PRSLT A B C RETURN PRSLT END PSUM END PSUMSMODULE main module gt Figure 6 3 A Pascal Program With External Linkages 6 7 Separate Compilation Program Linkage Relocation and Execution Invoking an External Procedure or Function As was discussed above except for the physical location of the object external objects and private objects are treated identically by the compiler at the source language level This implies in particular that a Pascal program invokes an external procedure or function in exactly the same manner as a private Pascal procedure or function The necessary linkages to the external routine are handled by the compiler and the interpreter From the point of view of the external module an external procedure or function is called from a Pascal progr
118. ultiplying operator factor multiplying operator DIV MOD AND lt factor gt lt variable gt lt unsigned constant gt lt expression gt lt function designator gt set NOT factor function designator gt function identifier lt function identifier actual parameter actual parameter function identifier identifier set lt element list lt element list element element empty lt element gt expression expression expression procedure statement procedure identifier procedure identifier actual parameter actual parameter procedure identifier identifier Syntax Summary PASCAL 80 G 4 The BNF Description of Pascal Cont d lt actual parameter gt lt expression gt lt variable gt lt go to statement GOTO label lt empty statement empty empty structured statement compound statement conditional statement repetitive statement with statement lt compound statement BEGIN statement statement END conditional statement if statement case statement lt if statement IF expression THEN statement IF expression THEN statement ELSE statement lt case statement CASE expression OF case list element
119. update the data in the record Information Retrieval Program SEEKEX PAS PASCAL SEEKEX This starts SEEKEX PAS running assuming it has been compiled If it has not been A compiled yet do so by typing PASCAL COMP SEEKEX PAS and then run it by typing gt SEEKEX The system will respond with the following Display which record Enter number 10 NO SUCH RECORD Display which record Enter number 5 Criss Mathews Female Social security number 435 Birth date 5 30 75 Number of dependents 0 Debts 0 Single Do you wish to change this record Y First name XXXX Last name YYYY S S number 999 M ale or F emale M Input birth date Month 5 Day 16 Year 58 Number of dependents 0 Amount of money owed 0 Marital Status M arried S ingle D ivorced W idowed S Display which record Enter number lt cntrl Z gt PASCAL 80 Vv r gt QUIT The record numbers that exist are numbered 0 through 8 5 6 PASCAL 80 Example Programs SEEKEX PAS Program Listing program demo seek type Status married widowed divorced single date record month jan feb mar apr may jun jul aug sep oct nov dec day 144 313 year integer end person record allocated boolean name record first last string 20 end ssnum integer an Sex male female birth date dependents integer debts integer case marital status status of married
120. ured type pointer type lt simple type scalar type lt subrange type type identifier G 1 Syntax Summary G 2 The BNF Description of Pascal Cont d lt scalar type gt lt identifier gt identifier lt subrange type constant constant It lt type identifier gt lt identifier gt tt lt structured type gt lt unpacked structured type gt PACKED lt unpacked structured type gt lt unpacked structured type gt lt array type gt lt record type gt lt string type gt lt set type gt lt file type gt lt array type ARRAY index type index type OF lt component type gt lt index type gt lt simple type gt component type type record type RECORD lt field list END lt field list fixed part fixed part variant part variant part fixed part record section record section lt record section lt field identifier field identifier type empty variant part CASE lt tag field type identifier OF variant variant tag field lt field identifier empty lt variant gt case label list lt field list empty lt case label list case label case label case label constant string type STRING STRING unsigne
121. xt editor SOURCE PROGRAM PASCAL Loads the Run Time System PASCAL 80 which executes compiled PASCAL RUN TIME SYSTEM programs PASCAL 80 COMPILER COMP PROG Loads the compiler to convert the source program into an interpreted object form known as intermediate code or P code PROG Loads the intermediate code file SPA ON into the Run Time System and PROGRAM executes it 1015 1 Figure 1 1 Program Development Cycle 1 3 CHAPTER 2 LANGUAGE FEATURES As mentioned in the Introduction PASCAL 80 is an extension of Standard Pascal as defined in the PASCAL User Manual and it is assumed that the reader is familiar with the structure and characteristics of Standard Pascal In this chapter we will describe the features of PASCAL 80 in terms of Standard Pascal and present examples of all language extensions Program Structure The complete detailed PASCAL 80 syntax is presented in Appendix G the follow ing briefly describes the overall structure of a Pascal program Every PASCAL 80 program consists of a heading followed by a block which in turn is followed by the program terminator a The block contains a number of declaration parts which define all objects local to the block followed by the state ment part which specifies the actions to be performed on the declared objects program program heading block block lt labe declaration p
122. y difference between a normal declara tion and declaration within a public declaration record is that the former causes storage to be allocated within the Pascal program while the latter causes the Pascal program to access storage locations allocated externally to the program In all other ways a PASCAL 80 program treats private variables and external variables identically NOTE It is the programmer s responsibility to ensure that the structure and size of an external variable is consistent with the declaration of the variable within the public declaration record If this is not so unpredictable and usually disastrous results will occur The lt name gt field is an optional field If it is present it is accepted by the compiler but otherwise ignored Since the constant declaration part and lt type declaration part do not cause any storage to be allocated they are not explicitly associated with any external storage locations However they are necessary within a public declaration record so that the variables procedures and functions may be defined adequately The lt variable declaration part declares variables whose storage is allocated exter nally to the Pascal program The compiler allocates an Indirect Reference Pointer in the global environment for each such external variable An indirect reference pointer Is one word in length and is used to address the external variable The procedure and function heading p
123. y number ssnum 0 write Birth date print date birth 5 8 Li MONTH MONTH WT 2 B PASCAL 80 PASCAL 80 SEEKEX PAS Program Listing Cont d writeln Number of dependents dependents 0 writeln Debts debts 0 case marital status of married begin write Married on print date date married end widowed begin write Widowed married on print date date married end divorced begin write Divorced on print date date divorced end 7 single writein Single end case end with writeln writeln end display begin reset people people dat repeat writeln write Display which rec rd Enter number readin recnumber if not eof input then if display recnumber then begin write Do you wish to change this record readln ch if ch in y Y then initfile true end else writeln NO SUCH RECORD until eof input end Example Programs CHAPTER 6 SEPARATE COMPILATION PROGRAM LINKAGE RELOCATION AND EXECUTION The previous chapters describe the procedures for compiling and executing a PASCAL 80 program consisting of a single compilation unit This chapter describes the techniques available for partitioning a large program into separate compilation units for linking a PASCAL 80 program with external modules written in PL M 80 FORTRAN 80 or ASM 80 and for constructing a
124. ze of char length integer begin reset s SSS pos open SSS tor reading rewrite d DDD and create DDD if necessary length bufferread s buffer size read in the first chunk while length gt 0 do begin length bufferwrite d buffer size write full chunk length bufferread s buffer size andreadthe next end iflength 0 then write out the last bit of the file length bufferwrite d buffer length else eneu Errori in reading file de close s close d end INTERACTIVE Files In the PASCAL User Manual the statement read f ch is defined to be ch f get if f is of type TEXT FILE of char This def inition implies that a get f is executed upon opening the file so that the first assignment from the buffer variable will be valid This initial get f is a cumbersome constraint when the file is opened to an interactive terminal since a program will hang waiting for that initial character In order to solve this problem the file type INTERACTIVE exists A file of type INTERACTIVE i is similar toa file of type TEXT i in all pec save nat end ch is defined tobe getti ch f and a gef i is not performed when the f ilei is s opened The e predeclared f ile input is of type INTERACTIVE 25 d ee me POWTER Type In PASCAL 80 as in Standard Pascal the P POINTER type defines a set of values pointing to elements of a given type PASCAL 80
125. zed command 233 Command syntax requires a TO clause 234 Filename illegally duplicated in command 235 File specified in command is not a library file 236 More than 249 common segments in input files 237 Specified common segment not found in object file 238 Illegal stack content record in object file 239 No module header in input object file 240 Program exceeds 64K bytes When error number 24 occurs an additional message is output to the console STATUS 00nn D x T yyy S 22z where x represents the drive number yyy the track address zzz the sector address and where nn has the following meanings for floppy disks 01 Deleted record 02 Data field CRC error 03 Invalid address mark 04 Seek error 08 Address error DA ID field CRC error DE No address mark OF Incorrect data address mark 10 Data overrun or data underrun 20 Attempt to write on Write Protected drive 40 Drive has indicated a Write error 80 Operation attempted on drive which is not ready ISIS II Error Messages For hard disks nn has the following meanings ID field miscompare Data Field CRC error Seek error Bad sector address ID field CRC error Protocol violations Bad track address No ID address mark or sector not found Bad data field address mark Format error Attempt to write on Write protected drive Drive has indicated a Write error Operation attempted on drive which is not ready

PASCAL·SO USER`S GUIDE

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PASCAL·SO USER`S GUIDE