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Debugger Manual - Typewritten Software

1. The Debugger Manual describes the Debugger which is designed for use at the symbolic instruction xii Debugger Manual level It can be used in debugging FORTRAN Pascal and assembly language programs COBOL and BASIC in contrast are more conveniently debugged using special facilities described in their respective manuals The Linker Librarian Manual describes the Linker which links together separately compiled object files and the Librarian which builds and manages libraries of object modules DATA MANAGEMENT FACILITIES The CT DBMS Manual describes Convergent s data base management system CT DBMS which consists of 1 a data manipulation language for accessing and manipulating the data base and 2 utilities for administering the data base activities such as maintenance backup and recovery and status reporting The ISAM Manual describes both the single and the multiuser indexed sequential access method It specifies the procedural interfaces and how to call them from various languages and the utilities The Forms Manual describes the Forms facility that includes 1 the Forms Editor which is used to interactively design and edit forms and 2 the Forms run time which is called from an application program to display forms and accept user input The Sort Merge Manual describes 1 the Sort and Merge utilities that run as a subsystem invoked at the Executive command level and 2 the Sor
2. STARTING A PROCESS AT A SPECIFIED ADDRESS The foregoing commands always cause a process to Start running from the last breakpoint address To begin process execution at a different address for example at address addr type addr CODE G The address addr should be an expression that includes a user defined public symbol for example RgParam 5 or else it should have the form indicated below X y where x is an appropriate CS parameter and y is an appropriate IP parameter Each process has its own CS and IP registers in the 8086 80186 processors These registers point to the instructions currently being executed in that process The commands 10 0 CODE G and 100 CODE G both cause execution to begin at absolute address 100 However the command 10 0 CODE G sets CS to 10 and the command 100 CODE G sets CS to O0 CODE X EXECUTING INSTRUCTIONS INDIVIDUALLY To make the system execute the next instruction in the current process type CODE X After the system executes this instruction it opens and displays the next instruction Using Breakpoints 5 5 Thus you can type CODE X again and again to see a series of instructions displayed and executed one by one TO resume continuous execution of instructions after using CODE X either type CODE P or press GO Whenever you use the CODE X command to execute an instruction that loads a segment register two instructions are actually executed For example i
3. Space prompt You can then add your instruction To display and modify the next instruction in the patch area type your instruction and then press For example in response to the line displayed above by the Debugger you could type MOV AX WORD PTR 0 The Debugger then displays the next instruction in the patch area PatchArea 3 NOP You would follow the same procedure entering the instruction and then pressing for this instruction and for each of the succeeding ones in a series For example suppose you want to tell the Debugger to take the breakpoint if the value of memory location DS 0 is 200h After all of your instructions are entered the Debugger display looks like the example shown below PatchArea h NOP MOV AX WORD PTR 0 PatchArea 3 NOP CMP AX 200 PatchAreat6 NOP JE 5 PatchArea 8 b NOP MOV AL O PatchArea 0A h NOP DEBUG PatchArea 0B h NOP MOV AL OFF PatchArea 0D NOP DEBUG Instructions that you add to the patch area must set the register AL to OFFh if the breakpoint is to be taken If the breakpoint is not to be taken your instructions must set AL to Oh The original value of the AX register is restored after the condition is evaluated So that control will return to the Debugger the last instruction in the relational condition must be DEBUG INT 3 You can set more than one conditional breakpoint by specifying an additional parameter for the CODE A command This parameter s
4. This command displays the contents of the 8087 registers NOTE You should use CODE Z only if your system has an 8087 co processor For example suppose your system has only an 8086 80186 processor If you enter CODE Z then your system will enter a perpetual WAIT state because the 8087 co processor is not there In such a case the debugging process as well as any other processes will halt and you will not be able to enter any instructions or commands from the keyboard The only solution is to re boot your system 7 2 Debugger Manual 8 DEBUGGER MODES The Debugger operates in three modes simple mode multiprocess mode and interrupt mode o The simple and most often used mode applies to the debugging of a single process user task such as a compiled BASIC program o The multiprocess mode applies to the debugging of a multiprocess user task whose operation depends on the continuous execution of all processes except the ones that are explicitly Stopped at breakpoints o The interrupt mode applies to the debugging of interrupt handlers or else to debugging that requires that breakpoints be set in the operating system Kernel The following paragraphs describe how these three modes are related to the different ways of entering the Debugger SIMPLE MODE You invoke this mode by pressing ACTION A This mode also occurs when a CODE B breakpoint is executed after ACTION A invokes the Debugger You can al
5. 06 30F0 0C9C 1 31FE 07 3102 12D2 1 3202 08 3114 5257 1 3214 13 31DA 082F 320A Figure 13 1 Example of Processes Displayed by CODE S Each line in this display corresponds to a process that is currently active in the system The number at the beginning of each line is a process identifier PID The column headings in this display are defined below id The process identifier number oPcb The address of the process control block for that process The address is relative to the operating system s data segment 13 2 Debugger Manual cs ip The address of the next instruction to be executed by the process link A link address used by CTOS to keep processes threaded st A byte containing status flags pr The priority of the process ss sp The address of the top of the stack for the process bp The base pointer of the process ds The data segment of the process exch For that process the default exchange for responses OExtPcb The address of the extended PCB The next items the Debugger displays are the Run Queue and the Exchanges See Figure 13 2 below Run Queue 00 01 02 13 Exchanges oExchg oMsgHead oMsgTail oPcbHead oPcbTail 01 31F4 3458 3458 0000 3084 03 3204 0000 0000 30DE 30DE 05 3214 0000 0000 30F0 30F0 0A 323C 0000 345E 30cc 30cc OF 3264 3452 3452 0000 31C8 11 3274 0000 0000 30BA 30BA 1c 32cc 0000 3458 3102 3102 1E 32DC 0000 0000 3114 3114 Figure 13 2 Example of a Run Queue and
6. Exchanges Displayed by CODE S The Run Queue display lists the processes that are ready to run in priority order These processes are active instead of WAITing Advanced Display Commands 13 3 Each line in the Exchanges display describes the State of an exchange The first number on each line is an exchange identifier The addresses that appear as column headings are all relative to the operating system s data segment These addresses are explained below oExchg The address of the exchange oMsgHead If messages are queued at the exchange oMsgHead is the address of the first message in the queue oMsgTail If messages are queued at the exchange oMsgTail is the address of the last message in the queue oPcbHead If processes are queued at the exchange oPcbHead is the address of the first process in the queue oPcbTail TE processes are queued at the exchange then oPcbTail is the address of the last process in the queue If messages are queued at the exchange then both oMsgHead and oMsgTail are non zero If processes are waiting at the exchange then both oPcbHead and oPcbTail are non zero Either messages or processes not both are queued at an exchange To obtain a display of processes or of the point ers to messages waiting on exchange k type k CODE S For example to obtain a display of the processes or of the pointers to messages waiting on exchange 7 type 7 CODE S Typical Debugger responses are show
7. FORTRAN 86 Pascal and PL M WHO SHOULD USE THIS MANUAL This manual is intended for programmers who are familiar with assembly language and who have some experience in debugging software Overview 1 1 Because the Debugger displays instructions of the Intel 8086 80186 microprocessor users should be familiar with the 8086 80186 instruction set HOW TO USE THIS MANUAL The sections in this manual fall roughly into two groups Sections 1 through 7 describe elementary debugging procedures such as working with memory contents using breakpoints working with registers and using fundamental display commands These are the procedures used most often in debugging Sections 8 through 14 describe more advanced features of the Debugger including its three modes of operation how it manages memory working with overlays and ports the histogramming facility the use of breakpoints in interrupt handlers and several infrequently used display commands If you are new to debugging we recommend that you practice using the procedures explained in the first half of this manual possibly in the presence of someone who is familiar with debugging Although reading this manual cover to cover before you start debugging a program may be useful you will probably find that you learn more quickly by using the manual during actual debugging sessions If you are familiar with general debugging procedures you can use this manual as a refere
8. Symbol File 3 3 CODE G Starting a Process at a Specified Address 5 5 CODE H Invoking the Histogram Facility 11 1 CODE I Setting Interrupt Level Breakpoints 12 1 CODE K Deactivating the Debugger Killing the Debugger 14 1 CODE L Turning the Line Printer Echo ON OFF 14 1 CODE N Displaying Linked List Data Structures 13 1 CODE 0 Searching for a Byte Pattern in Memory 4 6 CODE P Proceeding from a Breakpoint 5 4 CODE O Querying the Histogram Facility 11 3 CODE R Changing the Base of the Number System 3 5 CODE S Displaying the Status of Processes and Exchanges 13 2 Alphabetical List of Commands C 1 CODE T Displaying a Trace of the Stack 7 1 CODE U Displaying the User Screen 7 2 CODE X Executing Instructions Individually 5 5 CODE Z Displaying the Contents of the 8087 Registers 7 2 CODE J CODE M CODE V CODE W and CODE Y are not implemented in the present Debugger c 2 Debugger Manual APPENDIX D THE DEBUG FILE UTILITY The Debug File utility lets you examine and modi fy the data in files and devices It does not let you edit a run file However you do use this utility to patch run files and libraries To invoke this utility from the Executive enter the utility name in the command field and press RETURN The Debug File command form will then appear COMMAND Debug File DEBUG FILE COMMAND FORM File Name Write Image Mode where File Name
9. THE 8087 REGISTERS i rne DEBUGGER MODES eere SIMPLE MODE eos 5 5 Oe Cw 0 MULTIPROCESS MODE o o oooooooo oo o INTERRUPT MODE oooorooonnonnonrono oooo USING MULTIPROCESS MODE ENTERING MULTIPROCESS MODE VIA ACTION B PROCEEDING CODE P AND EXITING KEYBOARD AND VIDEO SWAPPING SWAPPING OVERLAYS AND PORTS DEBUGGER SWAPPING ooooooonoooaoonoono o EXAMINING CODE IN AN OVERLAY READING AND WRITING TO PORTS Debugger Manual I WNE ererr 10 1 10 1 10 2 10 2 11 THE HISTOGRAM FACILITY 11 1 CODE H INVOKING THE HISTOGRAM FACILITY 11 1 CODE Q QUERYING THE HISTOGRAM FACILITY 11 3 TURNING OFF THE HISTOGRAM FACILITY 11 4 12 BREAKPOINTS IN INTERRUPT HANDLERS 12 1 CODE I SETTING BREAKPOINTS IN INTERRUPT HANDLERS x99 se an ee ste er ym wu Beene wise cw URL i Tw 12 1 ASSEMBLY LANGUAGE CALLS THE INT 3 INSTRUCTION cuina e Gite Seiten 12 2 13 ADVANCED DISPLAY COMMANDS 13 1 CODE N DISPLAYING LINKED LIST DATA STRUCTURES oo s e sae aeia ea 9 vr s 13 1 CODE S DISPLAYING THE STATUS OF PROCESSES AND EXCHANGES 13 2 14 OTHER ADVANCED COMMANDS 14 1 CODE K DEACTIVATING THE DEBUGGER KILLING THE DEBUGGER ooooooooooo o o 14 1 CODE L TURN LINE PRINTER ECHO ON OFF 14 1 APPENDIXES Appendix A STATUS MESSAGES A 1 Appendix B COMMAN
10. a symbolic instruction that is ad dressed by a long pointer type addr of instruction pointer CODE MARK After you enter the CODE CODE gt or CODE MARK command the open location is the location addressed by the pointer For example suppose you wish to display the byte addressed by a pointer at location 244 You could first fetch the pointer and then fetch the byte 244 246 2199 04AE 00 or you could simply use the CODE command 244 CODE lt 00 4 2 Debugger Manual DISPLAYING SEVERAL LOCATIONS AT ONCE You can also use the memory examination commands to display several locations at once To do so when you type the parameter precede it with a number indicating how many locations you want displayed In response the Debugger displays the Specified number of parameters and keeps the last parameter open For example to display three words starting with the word that begins at location DS 100 type 3 DS 100 A typical Debugger response appears below 3 DS 100 gt 1F20 0AF 102 2F30 OAF 104 30FA DEBUGGER PROMPTS The Debugger always prompts you when it is ready for more input The type of prompt depends on the open location as explained below o If no location is open which happens if the Debugger was just entered or if the previous command closed all of the open locations then the Debugger issues the prompt that cor responds to the circumstances See the Debugger Prompts sub
11. control gt the system has abnormally terminated DEBUGGER DISPLAYS When the Debugger becomes active because a process has reached a breakpoint the Debugger displays a description of the break This description consists of the breakpoint address together with the number of the process that has been suspended Then the Debugger displays the Debugger prompt and waits for commands While waiting the Debugger treats all keyboard input as part of its command input EXITING FROM THE DEBUGGER To leave the Debugger press the GO key The Debugger responds by restoring the screen that was present before you began using the Debugger After you press GO to leave the Debugger the operating system directs all keyboard input toward a user process You can also press ACTION FINISH to terminate the current program and invoke the Exit Run File 3 2 Debugger Manual USING THE DEBUGGER AS A CALCULATOR You can use the Debugger as a calculator at any time To do So press ACTION A enter an expression to be evaluated and then type an equals sign For example if you type 3 7 the Debugger returns 15 hexadecimal You can also use the calculator mode to change the number base in which the Debugger expresses values For example if you type 800 the Debugger returns 800 which simply indicates that the hexadecimal value 800 is equal to itself To obtain a display of this value in decimal notation type 10 CODE R and
12. in question is not available after a CODE I breakpoint has been taken or when inter rupts are disabled Not enough parameters You must enter the command again with the cor rect number of parameters System error while opening a symbol file A file system error occurred when the Debugger tried to open the symbol file You should verify that the file name is spelled correctly Status Messages A 1 Not a symbol file The filename parameter in the CODE F command is not the name of a symbol file Check the Spelling No such command That command does not exist Refer to Appendix B Command Summary for a list of all of the Debugger commands Not implemented The specified command is not implemented in the Debugger Non existent memory No physical memory exists at the specified ad dress Too many breakpoints The Debugger permits only 16 breakpoints at one time Radix must be between 2 and 16 The parameter of the CODE R command must be in the range from 2 to 16 decimal inclusive Expected numeric parameter not found You must use a numeric parameter with this command No such breakpoint No breakpoint has been set at the address given in the CODE C command Cannot proceed You cannot invoke CODE P to resume a process that is already running No bounds set You must set the upper and lower bounds before you turn on the histogrammer A 2 Debugger Manual Histogrammer ON This message simp
13. is the name of the file or device that you want to examine or modify Write asks you to enter Yes or No default is No to indicate whether you want to modify any data If you enter Yes you will be able to modify the data Image mode asks you to enter Yes or No default is No to indicate how you want the Debug File utility to inter pret the data in the run file If you enter Yes the utility interprets the data exactly as the data appears in the run file Otherwise the utility interprets the data the way the data appears when loaded in memory The Debug File Utility D 1 WARNING Be very careful not to damage the CTOS file System by writing to a file or to a device such as a floppy disk drive that you have opened via this utility PROMPTS AND COMMANDS When invoked this utility prompts you with a percent sign You can use all the Debugger commands except those pertaining to breaking and proceeding as described in Section 5 above to examine and modify the data in a file or device The CODE S process and exchange status command and the CODE T stack trace command work properly only if the file being debugged is the crash dump file Sys lt Sys gt CrashDump Sys EXITING To exit from this utility press either FINISH or GO Any modifications you made to the data in the file or device are properly recorded on the disk only if you press FINISH to exit from the utility When
14. on the video screen after the user enters a command is indicated in the following way h Debugger Manual 2 CONCEPTS This section describes the concepts and terminology that are fundamental to understanding how the Debugger functions COMMAND PARAMETERS All Debugger commands have the same format from zero to three typed in parameters followed by one command keystroke Some commands are entered by holding down the CODE key and pressing another key at the same time These commands are represented in the format CODE X where X is the value of the Second key The following examples illustrate the different command formats a command with no parameters CODE R a command with no parameters 38DD CODE B a command with one parameter 10 8100 CODE H a command with two parameters 112A 2F20 ABC CODE O a command with three parameters The command keys are listed below o the up arrow f o the down arrow o the left arrow or CODE o the right arrow or CODE gt Oo MARK or CODE MARK Oo RETURN o the equals sign Concepts 2 1 o CODE an alphabetic key such as CODE C The Debugger accepts parameters similar to the parameters permitted in assembly language The acceptable Debugger parameters are indicated below o constants numbers ports and text o symbols o composite parameters formed using parentheses o the minus sign o the PTR pointer operator which indicates th
15. send and receive mail The CT MAIL Administrator s Reference Manual provides the System Administrator with instruc tions for installing configuring and maintain ing the CT MAIL electronic mail system setting up communication lines creating and maintaining mail centers adding mail users creating distribution lists and troubleshooting Multiplan is a financial modeling package designed for business planning analysis budgeting and forecasting The Business Graphics User s Guide introduces Business Graphics to the first time user It provides step by step lessons that describe basic Business Graphics operations The lessons show how to execute operations and apply them to sample charts The Business Graphics Reference Manual is a reference tool for users already familiar with xiv Debugger Manual Business Graphics It describes the Business Graphics keyboard and screen box and arrow cursor movement obtaining information from Multiplan operations and plotter configurations The Graphics Programmer s Guide is a reference for applications and Systems programmers It describes the graphics library procedures that can be called from application systems to generate graphic representations of data and it includes a Section on accessing Business Graphics from an application system The Font Designer Manual describes the inter active utility for designing new fonts character sets for the video disp
16. Breakpoint A user defined point in the code for a process Execution stops when a process reaches a breakpoint Bucket A small region of memory measured in multiples of 16 decimal bytes used by the Debugger s histogram facility Byte pattern User defined group of byte Specifiers The specifiers are separated by commas and enclosed in double quotation marks Byte specifier Sequence of two digit hexadecimal numbers or a string of characters enclosed in single quotation marks Clear Remove a breakpoint from a particular location in memory Code listing English language display of code generated by a compiler or translator Crash dump Output memory dump caused by a system failure Current process The process identified by the PR register in the Debugger Any registers that are read or written by the Debugger are for the current process Current value The value most recently typed by the user or the value most recently displayed by the Debugger Echo Repetition on a line printer or on a screen of instructions entered by the user and or material displayed by the Debugger Exchange Path on which a process waits for or receives messages or communications from another process or processes Histogram Debugger facility that displays the frequency with which a process refers to each memory location in a user specified range Glossary 1 Indexed address Address expression that uses index registers Interr
17. Command Summary gives a functional summary of each command Appendix C Alphabetical List of Commands lists the commands alphabetically and provides page number references to the sections of the manual where each command is explained in detail A glossary has been included at the end of this edition Summary of Changes xvii 1 OVERVIEW INTRODUCTION The Debugger is a software tool that works in real time and lets users perform the following tasks o examine and change data stored in memory or in registers o set and clear absolute breakpoints and condi tional breakpoints o produce formatted displays of memory contents o search memory for a pattern of bytes o read and write to I O ports o execute program instructions one at a time single step o assemble symbolic user input into binary ma chine instructions o disassemble the contents of memory into assembly language source instructions You perform these tasks by entering commands sometimes accompanied by parameters This manual describes all of the Debugger commands and explains how to use them The Debugger runs concurrently with other user and system processes and responds to commands as you type them The parameters of Debugger commands can include numeric literals and fundamental 8086 80186 symbols and also symbols defined in the program being debugged You can use the Debugger with programs written in assembly language compiled BASIC FORTRAN
18. D SUMMARY B 1 Appendix C ALPHABETICAL LIST OF COMMANDS i 629 x ym y nS C 1 Appendix D THE DEBUG FILE UTILITY D 1 Appendix E OPERATING NOTES E 1 GLOSSARY 9 umm y iR RD Wiel eee Glossary 1 Contents v LIST OF FIGURES Figure Page 1 1 The Debugger in Relation to Other Steps in Executing a Program 1 3 1 2 The Debugger s Access to Other Software and PU VSS is ta sara E Eo xe e dede AS 1 3 13 1 Example of Processes Displayed by CODESS en is Sot Shard Gia Weed wel ene 13 2 13 2 Example of a Run Queue and Exchanges Displayed by CODE S 13 3 LIST OF TABLES Table Page 4 1 Examples of Byte Patterns 4 7 vi Debugger Manual GUIDE TO TECHNICAL DOCUMENTATION This manual is one of a set that documents the Convergent Family of Information Processing Systems The set can be grouped as follows Introductory Installation Guide Operator s Guide Executive Manual Context Manager Manual Status Codes Manual Installation Guide NGEN Operator s Guide NGEN Hardware NGEN Processor Manual Model CP 001 Dual Floppy Disk Manual Floppy Hard Disk Manual Diagnostics Manual Keyboard Manual Power System Manual Monochrome Monitor Manual Model VM 001 Color Monitor Manual IWS Workstation Hardware Manual Peripherals Hardware Manual IWS Peripherals Hardware Manual SMD Version AWS AWS 210 Hardware Manual AWS 220 230 240 Hardware Manual AWS Color Wo
19. DEBUGGER MANUAL Specifications Subject to Change Convergent Technologies Convergent CTOS CT BUS CT DBMS CT MAIL CT Net AWS IWS and NGEN are trademarks of Convergent Technologies Inc Third Edition November 1983 A 09 00320 01 A Copyright O 1983 by Convergent Technologies Inc CONTENTS GUIDE TO TECHNICAL DOCUMENTATION Vid SUMMARY OF CHANGES oooooooooooooooooo XVii 1 OVERVIEW 5 amp ikx39 gh nsn cw onp Sp oom ehh enw ym c Sew 1 1 INTRODUCTION sapa eiaa as 2 1 1 WHO SHOULD USE THIS MANUAL 1 1 HOW TO USE THIS MANUAL secie ews asse ws oani 1 2 CONVENTIONS USED IN THIS MANUAL 1 4 2 CONCEPTS 4 24 5 5 Wie io eS 2 1 COMMAND PARAMETERS ooooooooooooooooo o 2 1 CONSTANTS NUMBERS PORTS AND TEXT 2 3 NumbersS3oeess3c s AAA Cotte d 2 3 POXUSis n3 o e ss ERI US ia Ug S78 2 3 TER E ida is Sog wu iie rri decer ce D deri m artes rs 2 4 SYMBOLS 444399350 eee eeu e Ge LS a aa rien oe 2 4 ADDRESS EXPRESSIONS ooooooooooooooo o o 2 5 SYMBOLIC INSTRUCTIONS eses esias aaas 2 5 CURRENT VALUE 512435699 99 ie urs 2 5 DEBUGGER MODES 5 45 4 x o rwr Rr RU eS 2 6 3 GETTING STARTED WITH THE DEBUGGER 3 1 ENTERING THE DEBUGGER oooooooooooo o o 3 1 Debugger PromptS o oooooooooooooo o 3 2 Debugger DisplayS ooooooooooooooo o 3 2 EXITING FROM THE DEBUGGER 3 2 USING THE DEBUGGER AS A CALCULATOR 3 3 CODE F OPENING A S
20. RN o 1 o If you press RETURN the previously open location closes and no new locations are opened If you press f the previous location opens If you press the next location opens Examining and Changing Memory Contents 4 5 The Debugger interprets the words next and previous according to the mode in which a location is open For example next can refer to the next byte the next word or the next instruction CODE 0O SEARCHING FOR A BYTE PATTERN IN MEMORY The CODE O command searches for a byte pattern in memory A byte pattern is a user defined group of byte specifiers separated by commas and enclosed in double quotation marks A byte specifier is either a sequence of two digit hexadecimal numbers or a string of characters enclosed in single quotation marks Examples of byte patterns appear in Table 4 1 below To search for a given byte pattern type lower addr upper addr byte pattern CODE O For example to search for the byte pattern 30 31 within the range of addresses from 5FE6 0C to 5FE6 100 type 5FE6 0C 5FE6 100 30 31 CODE O The Debugger searches for a byte pattern within the range of addresses starting at lower addr and ending at upper addr If the pattern is found then the Debugger displays the pattern at the address at which it was found and changes lower addr to the address of the first byte following the pattern To make the Debugger continue the search begin ning at the new lo
21. SWAPPING The Debugger requires approximately 55K bytes of memory However under some circumstances for example if you are debugging the Word Proces SOr you can debug a program that occupies all of memory theoretically leaving no room for the Debugger The Debugger manages memory according to the procedures described below o If enough memory is available the Debugger uses memory that is not used by the other processes o If enough memory is not available the Debugger swaps out part of the user s program provided swapping out is possible When the Debugger swaps out part of the user s program program execution is not affected Swapping can occur only when the Debugger is in simple mode In simple mode all user processes are suspended when they reach a breakpoint See also Section 8 Debugger Modes NOTE The Debugger swapping mechanism is not related or connected in any way to the Virtual Code Segment Management Facility Swapping Overlays and Ports 10 1 EXAMINING CODE IN AN OVERLAY An overlay is a part of a program that remains on a disk until you call it using the CALL operation The Debugger can display instructions that are contained in an overlay even if the overlay is not present in memory For more information about overlays refer to the Virtual Code Segment Management section in the CTOS Operating System Manual To display instructions contained in an overlay type symbolic a
22. YMBOL FILE 3 3 CODE R CHANGING THE BASE OF THE NUMBER SYSTEM 25e9992 9 9 9 e 3 5 4 EXAMINING AND CHANGING MEMORY CONTENTS 4 1 LOOKING AT MEMORY seses tede epee wie worm es 4 1 Using Pointers to Display Memory CONTES ee cee seet ewe kr e m Rm Tv 4 2 Displaying Several Locations at Once 4 3 Debugger PromptS o oooooooooooooo o 4 3 CODE D DISPLAYING THE CONTENTS OF MEMORY 56 959955 99 E 4 3 CHANGING THE CONTENTS OF A MEMORY LOCATION iaa a a a a m a as 4 4 Changing Instructio0NS o ooooooooo 4 5 Contents iii OPENING A NEW LOCATION c ccoooooooooo o CODE O SEARCHING FOR A BYTE PATTERN IN MEMORY c ceoncsosconsccsc no oe USING BREAKPOINTS coocoooooooooooooo CODE B SETTING AND QUERYING BREAKPOINTS ooooocooooacsonsonnonoooo CODE C CLEARING BREAKPOINTS CODE A SETTING CONDITIONAL BREAKPOINTS CODE P PROCEEDING FROM A BREAKPOINT CODE G STARTING A PROCESS AT A SPECIFIED ADDRESS oooo oo ooo noo CODE X EXECUTING INSTRUCTIONS INDIVIDUALLY essees esaad es tetra 9 e y Ren CODE E BREAKING AFTER THE CURRENT INSTRUCTION seses seste seen mm ii ne wo WORKING WITH REGISTERS THE PROCESS REGISTER n EXAMINING AND MODIFYING REGISTERS USING REGISTER MNEMONICS ELEMENTARY DISPLAY COMMANDS CODE T DISPLAYING A TRACE OF THE STACK CODE U DISPLAYING THE USER SCREEN CODE Z DISPLAYING THE CONTENTS OF
23. ached a breakpoint For example if Process 2 is the process that most recently reached a breakpoint then PR is set to 2 When you invoke the Debugger from the Executive or from the Context Manager using CODE GO just before the execution of an application system begins PR is set to the identifier of the first user process All Debugger commands that involve processes treat the process with which they are concerned as the current process For example whenever registers are read or written to the register of the current process is used EXAMINING AND MODIFYING REGISTERS To debug a single process program you normally do not need to refer to PR at all However to debug a multiprocess program you must know which of the processes involved is the current process You can examine and change PR the same way you would examine and change any other word location by opening it and then entering a new parameter if desired For example if the current process is number 4 and you want to change it to number 7 type PR gt Working with Registers 6 1 In this case the Debugger responds by displaying PR gt 4 to which you respond by typing 7 The current process is now number 7 When a multiprocess program is debugged the 8086 80186 register mnemonics indicate the machine registers that are associated with the current process Likewise the IP instruction pointer and FL flags registers indicate the instruction pointe
24. al Model CP 001 describes the Processor Module which houses the Processor board Memory board I O board Video Keyboard board and Motherboard It details the architec ture and theory of operations of the printed circuit boards external interfaces and the Memory Expansion Cartridge as well as the X Bus Specifications The Dual Floppy Disk Manual and the Floppy Hard Disk Manual describe the architecture and theory of operation for the NGEN modules They discuss the respective disk drives and controllers and contain the applicable OEM disk drive manuals Documentation Guide ix The Diagnostics Manual describes the diagnostics available for the NGEN workstation It discusses the Processor Module s bootstrap ROM program and error codes and individual software diagnostics for modules in the workstation The Keyboard Manual describes the theory of operation for the NGEN keyboard The Power System Manual describes the operation and connections for the 36 Volt Power Supply and the dc dc converters used with the NGEN work station The Monochrome Monitor Manual Model VM 001 describes the operation and connections of the 12 inch Monochrome Monitor used with the NGEN workstation The Color Monitor Manual describes the operation and connections of the 15 inch Color Monitor used with the NGEN workstation IWS The Workstation Hardware Manual describes the mainframe keyboard and video display for the IWS f
25. amily of workstations It specifies system architecture printed circuit boards Mother board Processor I O Memory Multiline Communi cations Processor Video Control Graphics Control Board ROM and RAM Expansions keyboard video monitor Multibus interface communications inter faces power supply and environmental charac teristics of the workstation The Peripherals Hardware Manual describes the non SMD single board Mass Storage Subsystem MSS and Mass Storage Expansion MSX disk subsystems for the IWS family of workstations It contains descriptions of the disk controller Motherboard the two controller boards for floppy and Win chester disks power supplies disk drives and environmental characteristics The IWS Peripherals Hardware Manual SMD Version describes the SMD MSS and MSX disk subsystems having one controller board x Debugger Manual AWS The AWS 210 Hardware Manual describes the main frame keyboard and video display of the AWS 210 workstation It specifies architecture theory of operation of the printed circuit boards Mother board Deflection and CPU keyboard video monitor expansion interface cluster communica tions interface power supply and environmental characteristics of the workstation The AWS 220 230 240 Hardware Manual describes the mainframe keyboard disk controllers and video display of the AWS 220 230 and 240 workstations It specifies architecture theor
26. ase from 2 to 16 can be used All memory data is displayed using the radix that is in effect at that time Unless you change it this radix is hexadecimal To set the output radix to another base type k CODE R where k is a number from 2 to 16 decimal To change the output radix back to hexadecimal from any other base type 16 CODE R or else simply type CODE R Getting Started with the Debugger 3 5 Tf however the output radix is already hexadecimal and you type CODE R alone with no parameters the output radix changes to decimal You can also use the CODE R command to display the current value To do so type an equals sign after you specify the base in which you want values to be displayed In this case the equals sign specifies the most recent value For example if you want the hexadecimal value 100 displayed in decimal notation you would enter 10 CODE R 100 2 The Debugger responds by displaying the decimal value 256 NOTE The output radix applies only to numbers that the Debugger displays Numeric constants that you enter are interpreted or evaluated independently of the output radix as explained in the Numbers subsection in Section 2 Concepts 3 6 Debugger Manual 4 EXAMINING AND CHANGING MEMORY CONTENTS LOOKING AT MEMORY After entering the Debugger you can examine the contents of memory by typing either a parameter that designates a machine address a register or an inter
27. below 1 CODE Q 200 20 1 300 2 1 300 12 1 400 0C 5 600 6 1D 600 16 OF 600 26 9 700 2 OE 700 12 23 700 22 OD 700 32 Cd 8700 42 OE 700 52 4 800 7 7 In Range 0A5 Out of Range 6DB Total 780 This report displays the address of each bucket and indicates the value of the associated bucket counter It also displays a summary indicating the total number of samples taken the number of times that the instruction pointer was within the Specified range and number of times that the pointer was outside the range To obtain a display of the bounds and bucket size in the histogram enter CODE Q with no parameters as shown below CODE Q Pressing CODE Q also produces a report of the number of bytes required to contain the bucket counters as shown in the following display Lower PrimeEntry 9 Upper 1000 1 Bytes Bucket 10 Bytes required 0CO The Histogram Facility 11 3 If you enter either CODE Q or 1 CODE Q without having exited from the Debugger and run the histogram facility the Debugger displays the message No data In this case you must again enter the lower and upper bounds and the number of bytes per bucket and then enter CODE H or GO again to exit from the Debugger and run the histogram facility When you enter the Debugger again after a histogram has been displayed you can continue histogramming simply by exiting from the Debugger using GO or CODE P TURNING OFF THE HISTOGRAM FACILITY To t
28. bucket size to 64 bytes type 64 CODE H After setting the bounds and the bucket size Start the histogramming procedure by entering CODE H with no parameters as shown below CODE H The Debugger responds by displaying the message Histogram On before exiting to the program Note that CODE H is equivalent to GO When you enter CODE H the Debugger exits and the user program continues NOTE To support histogramming the debugger must allocate enough long lived memory to contain the bucket counters If this much memory is not available the debugger displays the message Not enough memory In this case the histogram facility will not start To avoid this situation you must either reorganize your program so the Debugger can acquire the necessary memory or specify a larger bucket size You must reenter the Debugger to obtain a display of the histogram report You can do so either by pressing ACTION A or by placing a breakpoint in the program before you start the histogramming facility NOTE Do not let your program call Exit i e do not let it terminate while histogramming is in progress If you do so the histogram information will be lost 11 2 Debugger Manual CODE O UERYING THE HISTOGRAM FACILITY Once you have entered the Debugger again you can obtain a display of the histogram report by entering CODE Q preceded by the parameter 1 as indicated below 1 CODE Q A typical Debugger response is shown
29. d range Thus you can measure program performance based on this information about where a program spends its time To generate a histogram the Debugger divides memory into small regions known as buckets Buckets are contiguous collectively they span the entire section of code being analyzed The Debugger maintains a set of counters for these buckets The Debugger creates a histogram by sampling the instruction pointer CP IP 60 times per second If CP IP refers to an address that is located in the section of code being analyzed the Debugger determines which bucket is referred to and adds to the counter for that bucket CODE H INVOKING THE HISTOGRAM FACILITY Before creating a histogram you must specify the lower and upper bounds addresses of the section of code to be analyzed To do so enter the CODE H command preceded by two parameters that specify the lower and upper bounds respectively as shown below parameter parameter CODE H For example to specify line number 10 of a compiled BASIC program as the lower bound and line number 1000 as the upper bound type 10 1000 CODE H In BASIC programs the symbolic name of a line number is the line number preceded by an character By default the bucket size is 16 decimal bytes To change the bucket size enter CODE H with one parameter Note that the bucket size must be a multiple of 16 decimal The Histogram Facility 11 1 For example to change the
30. ddr MARK If the overlay is not present in memory then the Debugger places braces around the symbolic address of the next instruction displayed using the DOWN arrow command For example the message Initialize 2 MOV BP SP indicates that the code segment containing the procedure called Initialize is in a swapped out overlay You cannot modify instructions that are contained in a swapped out overlay Patches that you make to swapped in overlays stay in effect only while the overlay is present in memory READING AND WRITING TO PORTS To read and write to ports use the left arrow and right arrow commands together with constants For example to read from the byte input port 17i type 17i To read from the word input port 3li type 31i gt 10 2 Debugger Manual In either of these cases after you type the constant the port becomes an open location You can then specify a new parameter to be written to the port Note that unlike reading from memory reading from a port can change the state of the System For example reading a character from the keyboard removes the character from the keyboard Swapping Overlays and Ports 10 3 11 THE HISTOGRAM FACILITY The Debugger s histogram facility lets you analyze a section of your program to see how often it executes given instructions The facility does so by displaying a list of how often the program refers to one or more memory locations within a user specifie
31. e CODE C command The Debugger uses hardware interrupts 1 and 3 Therefore user programs should not use hardware interrupts 1 or 3 Other parts of the operating System use other hardware interrupts Refer to the manual for your operating system to learn which of these other interrupts you should not use Breakpoints in Interrupt Handlers 12 1 ASSEMBLY LANGUAGE CALLS THE INT 3 INSTRUCTION If you code an INT 3 instruction in an assembly language program the system enters the Debugger when the INT 3 instruction is executed For example if you code an INT 3 instruction at location 9904 6A then when the program executes that instruction the system enters the Debugger In this case the system displays the following type of message Debugger call at 9904 6B in Process 8 Note that the address displayed in this message 9904 6B is located one byte after the INT 3 instruction 9904 6A The Debugger also disassembles the INT 3 instruction by displaying the DEBUG mnemonic as shown below 9904 6A h DEBUG 12 2 Debugger Manual 13 ADVANCED DISPLAY COMMANDS This section describes two commands that are used occasionally in advanced debugging CODE N displays linked list data structures CODE S displays system structures for the status of processes and exchanges CODE N DISPLAYING LINKED LIST DATA STRUCTURES The CODE N command displays linked list data structures You should use CODE N with the internal Debugger registe
32. e type of operand you are dealing with as shown in the following examples MOV BYTE PTR 14 2 MOV WORD PTR 14 2 In these examples BYTE PTR points to a byte and WORD PTR points to a word If the type of the operand is not implied you must use the PTR operator Never use PTR alone but always with BYTE or WORD o the following binary operators addition subtraction multiplication division o address expressions such as those shown below BX BP DI 3 o symbolic instructions such as those shown below PUSH BP MOV BP SP SUB SP 4 2 2 Debugger Manual CONSTANTS NUMBERS PORTS AND TEXT NUMBERS A number or numeric constant consists of digits belonging to the set of hexadecimal digits 0 through 9 and A through F The number can end with a decimal point or with an h A number that ends with a decimal point is a decimal number A number that ends with an h or that omits both the decimal point and the h is a hexadecimal number A number that begins with the characters A through F must have a leading zero 0 preceding the character Examples of numbers appear below 123h is a hexadecimal number 123 is a hexadecimal number 123 is a decimal number OAF is a hexadecimal number AF is not a valid number PORTS A port constant is a number followed by the character i or o An i indicates that the port is an 8086 80186 hardware input port An o indicates that the port is an o
33. ence Manual is a reference tool for sophisticated users of the Multimode Terminal Emulator It describes the MTE escape sequences and field verification program CP M 86 is a trademark of Digital Research MS GW and XENIX are trademarks of Microsoft Corp UNIX is a trademark of Bell Laboratories xvi Debugger Manual SUMMARY OF CHANGES This third edition A 09 00320 01 A of the Debugger Manual documents release 9 0 of the Debugger and replaces the second edition A 09 00011 01 C The major changes to the content and organization of the Debugger Manual are described below A new command CODE O enables you to search for a byte pattern in memory This new feature is described in Section 4 Examining and Changing Memory Contents A histogram facility has been added to the Debugger By using CODE H and CODE Q commands you can record how many times specified sections of code are entered and display this information Section 11 The Histogram Facility describes this new feature in detail Besides documenting these new features this edition of the Debugger Manual is organized to provide easy access to the different Debugger commands The commands are described functionally in the main sections of the manual The functions are arranged in order of complexity and frequency of use Examples of command entries and interpreted Debugger displays are included in the command descriptions In addition Appendix B
34. ide symbolic names for addresses For example with a suitable symbol file the instruction CALL OFFEF 336 might appear as CALL ErrorExit To suppress symbolic output press CODE F When you do so the following message appears Symbols OFF To enable symbolic output again press CODE F When you do so the following message appears Symbols ON The CODE F command suppresses only symbolic output You can use symbolic names as input any time you are using a symbol file 3 4 Debugger Manual When debugging a program that was not loaded by the Executive or the Context Manager you cannot open the symbol file unless you specify the program segment address of the task as shown below Segment filename CODE F For example to debug the program Fred whose base address is 12340h paragraph 1234h for the 8086 80186 microprocessor type 1234 Fred Sym CODE F Otherwise however you need not specify the program base address because the Debugger can determine it by making a call to the operating system If you are debugging the operating system you must type zero the base address of the operating System before you type the name of the symbol file as shown in the example below 0 OS Sym CODE F CODE R CHANGING THE BASE OF THE NUMBER SYSTEM The CODE R command changes the output radix The output radix is the base of the number system in which information is expressed Decimal hexa decimal octal or any other b
35. lay COMMUNICATIONS The Asynchronous Terminal Emulator Manual de scribes the asynchronous terminal emulator The 3270 Terminal Emulator Manual describes the 3270 emulator package The 2780 3780 RJE Terminal Emulator Manual de scribes the 2780 3780 emulator package The SNA Network Gateway Manual describes the SNA Network Gateway which supports data communica tions over an SNA network The SNA Network Gateway comprises the Transport Service and Status Monitor The Transport Service allows a Convergent workstation to function as cluster controller and forms the foundation for Conver gent SNA products The SNA 3270 Emulator Manual describes the SNA 3270 emulator package The SNA 3270 emulator provides CRT and printer subsystems in addition to a Virtual Terminal Interface for use in appli cation programs The X 25 Network Gateway Manual describes the X 25 Network Gateway which supports CCITT Recommendation X 25 communications over a public data network There are three levels of access to the network packet X 25 sequential access method and the Multimode Terminal Emulator X 25 communications option Documentation Guide xv The Multimode Terminal Emulator User s Guide introduces the Multimode Terminal Emulator to the first time user It describes the MTE video display keyboard display memory and advanced operations for the X 25 communications option The Multimode Terminal Emulator Refer
36. ly indicates that the histogram function is active Bucket size must be a multiple of 16 When using the histogram facility you must Specify a number of bytes that is a multiple of 16 No data You must run the histogramming facility to obtain data before you can use CODE Q to examine the data Lower bound is greater than upper The histogrammer requires that the lower bound address be numerically less than the upper bound address Expected parameter s not found The parameters of the specified command are not of the correct type or number PatchArea offset too large The offset in the PatchArea must not exceed 50 bytes Status Messages A 3 APPENDIX B COMMAND SUMMARY 1 The CODE R command and the equals sign neither open nor close any locations 2 5 The CODE X UP arrow and DOWN arrow commands close one location and open another 3 All other commands close all locations The Debugger parameters and commands and their effects are summarized in the following table Parameter s Command Effect CODE B Displays a list of all breakpoints addr CODE B Sets a breakpoint at addr when in simple or multi process mode CODE C Clears all breakpoints addr CODE C Clears the breakpoint at addr k addr CODE D Displays k bytes starting at addr CODE E CODE F Turns symbolic output ON and OFF filename CODE F Uses the symbol file segment CODE F Uses the symbol file with filename load offset addr CODE G Star
37. n below The first is for processes and the second is for messages Exchange 07 Processes 03 Exchange 07 Messages ADB2 1217 13 4 Debugger Manual 14 OTHER ADVANCED COMMANDS This section describes two additional advanced debugging commands You use these commands to deactivate the Debugger as opposed to exiting from it and to turn the line printer echo on and off CODE K DEACTIVATING THE DEBUGGER KILLING THE DEBUGGER Use the CODE K command to deactivate the Debug ger As used in this manual the term deactivate means to remove from the group of features available to the user Thus the CODE K command prevents you from using the Debugger at all When you press CODE K the Debugger displays a message asking whether you really want to deactivate it If so press CODE K again Once you press CODE K the second time you can reenter the Debugger only by pressing the RESET button located on the back of your workstation NOTE You must deactivate the Debugger using CODE K before you can install a different version of the Debugger CODE L TURN LINE PRINTER ECHO ON OFF The Debugger lets you obtain a duplicate of its Screen output on a line printer The CODE L command lets you obtain a printed copy of the dialogue that appears on the Debugger screen To activate this feature type CODE L Other Advanced Commands 14 1 If the line printer is properly connected and is online the followi
38. n the portion of code listed below if you use CODE X to execute the instruction LES BX bp 6 the instruction PUSH ES is also executed and the PUSH BX instruction is dis played as the open location as indicated below LES BX bp 6 PUSH ES PUSH BX CODE E BREAKING AFTER THE CURRENT INSTRUCTION To break after the current instruction type CODE E In most cases entering CODE E has the same effect as entering CODE X it lets you step over an instruction However if the instruction is a CALL CODE X executes the CALL instruction and then breaks at the first instruction in the called procedure In contrast CODE E executes the entire procedure and then breaks at the first instruction following the RETURN Therefore CODE E provides a convenient way to step over a procedure call NOTE You cannot use CODE E to break after an in struction that loads a segment register 5 6 Debugger Manual 6 WORKING WITH REGISTERS This section describes the Debugger s internal process register and explains how to examine and modify registers It also discusses the use of register mnemonics and tells how to proceed from a new Code Segment and Instruction Pointer CS IP using CODE G THE PROCESS REGISTER The process register PR is a Debugger internal register This register always identifies and keeps track of the current process The PR is set automatically to the process identifier of the process that most recently re
39. nal Debugger register followed by a command either or MARK The Debugger displays the contents of the designated address or register and opens that address or register so that you can change its contents o To display a single byte type addr o To display a single word type addr gt o To display a symbolic instruction type addr MARK For example to display one byte at address 0Al type OAL lt The Debugger will return one byte of data such as 1F To display one word starting at register location DS 100 type DS 100 The Debugger will return one word of data such as 1F20 To display the instruction at CreateISAM 10 type CreateISAM 10 MARK Examining and Changing Memory Contents 4 1 The Debugger returns the instruction at that symbolic address For example the MARK command might return h MOV AX WORD PTR BX Notice that when you press MARK a small right triangle appears on the screen to the right of what you typed USING POINTERS TO DISPLAY MEMORY CONTENTS You can also use indirect addresses to examine bytes words and instructions You do so by Specifying the address of a long pointer that addresses the byte word or instruction that you want to examine To display a single byte that is addressed by a long pointer type addr of byte pointer CODE To display a single word that is addressed by a long pointer type addr of word pointer CODE To display
40. nce guide In particular the appendixes provide a further distillation of the information in this manual including a list of error messages an explanation of the Debug File utility a summary and an alphabetical list of all commands and operating notes for using the Debugger with cluster systems and with dual floppy disk systems Appendix C also refers you to the page on which each command is described in detail Figures 1 1 and 1 2 illustrate the relationship between the Debugger and other elements of your system Specific information about the Debugger begins in Section 2 Concepts 1 2 Debugger Manual Program Compiler Object Module Symbol File Linker CTOS Library Run Executive Context Manager La 77 7 Debugger Figure 1 1 The Debugger in Relation to Other Steps in Executing a Program Image of a Program Debugger CTOS 8086 80186 Figure 1 2 The Debugger s Access to Other Software and Files Overview 1 3 CONVENTIONS USED IN THIS MANUAL o 1 4 Commands that consist of arrows up down right and left are shown in the text of this manual in the following way t P Commands that use the CODE key together with another key are shown in the following way CODE the name of the key Memory addresses are indicated in the follow ing way addr Names of files are indicated in the following way filename The solid right triangle which appears
41. ng message appears on the Screen Lpt echo ON If the line printer is not properly connected or if it is not online the following message appears on the screen Lpt echo OFF If you type CODE L again and again the echo feature alternates between its ON and OFF states You cannot use the Debugger s printer echo fea ture if the line printer is also being used by the operating system or by the program that is being debugged In the file Debugger CODE L takes an optional filename parameter as follows filename CODE L Filename is the name of the byte stream file that contains the screen output duplicate 14 2 Debugger Manual APPENDIX A STATUS MESSAGES The error messages that the Debugger displays are shown below in boldface type The explanation of each message appears in regular type Breakpoint already set A previous CODE B command already set a break point at the specified address Pattern not found The specified pattern was not found in the range of addresses given as parameters of the CODE O command Expected parameter not found You must use a string parameter with this com mand Segmented address parameter not found You must use an address parameter with this command Address must not be in an overlay You cannot modify code in an overlay Too many parameters You must enter the command again with the correct number of parameters Not allowed when interrupts are disabled The command
42. ng mode used in debugging a single process user task for example a compiled BASIC program Glossary 3 Stack A region of memory accessible from one end by means of a stack pointer Stack frame Region of a stack corresponding to the dynamic invocation of a procedure Consists of procedural parameters a return address a saved frame pointer and local variables Stack pointer The indicator to the top of a stack The stack pointer is stored in the registers SS SP Stack trace Debugger display of a stack organized by stack frames State variable Symbolic name of a register that contains data indicating the state of the Debugger for example PR IP or FL Symbol Sequence of alphanumeric and other characters under score period dollar sign pound sign or exclamation mark Symbolic instructions Instructions containing symbols that is mnemonic characters corre sponding to assembly language instructions These instructions cannot contain user defined public symbols System process Any process that is not terminated when the user calls Exit Text constant Sequence of characters enclosed by quotation marks User process Any process that is terminated when the user calls Exit Glossary 4 Debugger Manual
43. ons It describes the workstation switches and controls keyboard function and floppy disk handling viii Debugger Manual The Executive Manual describes the command inter preter the program that first interacts with the user when the system is turned on It describes available commands and discusses command execu tion file management program invocation and System management It also addresses status in quiry volume management the printer spooler and execution of batch jobs This manual now incor porates the System Utilities and Batch Manuals The Context Manager Manual describes and teaches the use of the Context Manager which allows the user to run applications concurrently and inter change them on the screen almost instantly The Status Codes Manual contains complete listings of all status codes bootstrap ROM error codes and CTOS initialization codes The codes are listed numerically along with any message and an explanation The NGEN Installation Guide describes the procedure for unpacking assembling cabling and powering up an NGEN workstation The NGEN Operator s Guide is a link between the operator the NGEN workstation and the work station s documentation The Operator s Guide describes the operator controls and the use of the floppy disk drives as well as how to verify that the workstation is operational and how to use software release notices HARDWARE NGEN The Processor Manu
44. ot change directly to the ACTION B mode The Debugger alone requires about 55K bytes of memory However the entire Debugger including its nonresident portion together with the program being debugged must Eit into the available memory If memory is insufficient a status message is displayed and the Debugger switches to simple mode Provided enough memory is available you can set a CODE I breakpoint in multiprocess mode at any time The Debugger goes into interrupt mode when a CODE I breakpoint is taken See Section 12 for more information about CODE I breakpoints If the current process as defined by the process register PR is not suspended the Debugger prompt is the pound sign If the current process has been suspended the Debugger prompt is an asterisk For more information about using multiprocess mode see Section 9 8 2 Debugger Manual INTERRUPT MODE This mode occurs when a user process reaches a CODE I breakpoint When the program reaches a CODE I breakpoint the Debugger takes control of the interrupt system and freezes the condition of the processor As in the multiprocess mode the entire Debugger must fit into the available memory If you set a CODE I breakpoint and enough memory is not available a status error message appears In the interrupt mode the Debugger prompt is an exclamation mark Debugger Modes 8 3 9 USING MULTIPROCESS MODE This section provides more details abo
45. output radix to k Displays status of all processes and exchanges Displays status of exchange k Displays a trace of the stack Displays a trace of k levels of the stack Causes a video display of either the user process or the Debugger procedures Executes an instruction and opens the next instruc tion Displays the contents of the 8087 registers Opens addr as a byte Opens k successive bytes Opens addr as a word Opens k successive words Opens addr as an instruc tion Opens k successive instruc tions Re displays the current value Command Summary B 3 value value B 4 GO RETURN Debugger Manual Opens the previous location Changes the current loca tion and opens the pre vious location Opens the next location Changes the current loca tion and opens the next location Exits from the Debugger and in simple mode pro ceeds from the current breakpoint Closes the open location APPENDIX C ALPHABETICAL LIST OF COMMANDS All of the commands that are presently implement ed in the Debugger are listed alphabetically below The page number at the end of each entry refers to the section in the manual where the command is described CODE A Setting Conditional Breakpoints 5 2 CODE B Setting and Querying Breakpoints 5 1 CODE C Clearing Breakpoints 5 2 CODE D Displaying the Contents of Memory 4 3 CODE E Breaking after the Current Instruction 5 6 CODE F Opening a
46. pecifies the PatchArea offset at which the relational condition begins Using Breakpoints 5 3 For example the following parameter and command 20 Initialize CODE A Set a conditional breakpoint at the location named Initialize whose relational condition begins at PatchArea 20 You can change an unconditional CODE B breakpoint into a conditional breakpoint at any time by typing addr CODE A After entering this command you must also add the conditional code in the PatchArea as explained above CODE P PROCEEDING FROM A BREAKPOINT To proceed from the most recently found breakpoint in the current process type CODE P The breakpoint remains in effect and the process continues If the process was not broken by the breakpoint the Debugger ignores the CODE P command In this case because the process is Still running you cannot logically command it to resume running To proceed and to break the kth time the breakpoint is reached instead of the next time it is reached type k CODE P where k is a decimal number CODE P with no parameters is equivalent to CODE P with a parameter of 1 To remove the breakpoint before proceeding type 0 CODE P 5 4 Debugger Manual If you entered the Debugger by pressing ACTION A you should enter the CODE P command to exit from the Debugger Pressing GO has the same effect as pressing CODE P that is it lets you proceed from the most recent breakpoint CODE G
47. ppose that you want to change the contents of DS 101 from 2F30 to 2F37 Location DS 101 is open and the Debugger prompts you with a space You type the right arrow shown below DS 101 The Debugger responds by displaying DS 101 2F30 After which you type 2F37 Location DS 101 now contains the value 2F37 4 4 Debugger Manual CHANGING INSTRUCTIONS Remember that assembly language instructions on the 8086 80186 processors have different lengths Therefore an instruction can include bytes of memory that are located beyond the bytes that the Debugger has displayed A Debugger command that replaces an instruction can also leave the last few bytes of the original instruction dangling after the end of the new instruction In such a case when the new instruction is shorter than the original one you should replace each dangling byte of the original instruction with a no operation NOP instruction The NOP instruction acts as a place holder For example suppose a comparison instruction is three bytes long and the jump instruction is two bytes long 24D 120 CMP AX WORD PTR BP 4 JMP 2 24D 122 h ADD AL 75 NOP As shown above when you write the jump instruc tion over the comparison instruction you must insert a NOP instruction after the jump instruc tion OPENING A NEW LOCATION The memory location that is open changes with each command that modifies the contents of memory There are three such commands Oo RETU
48. r and flags associated with the current process To examine the registers of other processes you must change PR by following the procedure ex plained above USING REGISTER MNEMONICS You can read and write to all of the registers listed below cs Code Segment DS Data Segment ES Extra Segment ss Stack Segment AX BX CX and DX are all general registers BP BX DI and SI are general registers and index registers The 16 bit FL register contains flags and the IP register contains the instruction pointer You can use register mnemonic symbols AX SI etc only as left side values In other words these symbols must be the first parameters in the commands that you use to examine or to change the contents of memory NOTE If you try to change the register SP system will abnormally terminate 6 2 Debugger Manual 7 ELEMENTARY DISPLAY COMMANDS This chapter explains how to use three basic De bugger commands to display a trace of the stack to display the user screen and to display the contents of the 8087 co processor CODE T DISPLAYING A TRACE OF THE STACK A stack trace consists of several numbered lines Each line number corresponds to a stack frame and the first line displayed corresponds to the current stack frame The CODE T command displays the procedure invocation stack for the current process To display the entire stack type CODE T To display the stack for the k most recent active procedu
49. re invocations type k CODE T For example to display the stack for the 6 most recent invocations type 6 CODE T A typical Debugger response is the display shown below 3108 12D2 14A 3 3 4F1F 3113 3116 581F 95 173C 1 4F1F 312A 4F1F 312E 3130 5EC8 0C4 4F1F 173C 4F1F 314D 313E 571C 255 26F0 47 4F1F 314D 4F1F 3158 3160 5920 6E 4F1F 2700 4F1F 3178 4F1F 31CD 318E 5FA9 70 2700 4E1F 0 600 4F1F 31CD Ur 0hNTPPBGO In this display the first column contains the level number for the current frame The second column contains the frame pointer BP for that frame and the third column contains the return address CS IP that will be effective when control returns to that level The remainder of each line contains the parameters that were passed to the procedure corresponding to the stack frame Elementary Display Commands 7 1 The Debugger estimates the number of parameter words displayed up to a maximum of six Therefore this number might not correspond to the number of parameters actually passed to the procedure CODE U DISPLAYING THE USER SCREEN When the Debugger is running it displays only the Debugger screen The Debugger does not display the screen generated by the user process To view the user screen without exiting from the Debug ger type CODE U Once the user screen appears press any key ex cept CODE U again to restore the Debugger screen CODE Z DISPLAYING THE CONTENTS OF THE 8087 REGISTERS
50. recently To display the current value again type an equals sign You can also use this instruction to display that value in a different number system provided you first change the radix by entering a CODE R Concepts 2 5 command See the example in Section 34 subsection CODE R Changing the Number Base DEBUGGER MODES The Debugger operates in one of three different modes depending on how you enter it Each of these modes simple mode multiprocess mode and interrupt mode is described in detail in Section 8 Debugger Modes 2 6 Debugger Manual 3 GETTING STARTED WITH THE DEBUGGER This section explains how to enter and exit from the Debugger how to use the Debugger as a calculator how to open symbol files and how to change the base of the number system in which the Debugger displays output data Some versions of the operating system are configured without the Debugger If the Debugger is not present in your OS and if you or a process tries to enter the Debugger then the operating System either places an error message on the Screen or else sounds the audible alarm ENTERING THE DEBUGGER You can enter the Debugger in any one of the following five ways 1 When you press the ACTION key and hold it down while you press the A key a procedure indicated throughout this manual as ACTION AU Y This is the most commonly used way to invoke the Debugger In this mode the Debugger suspends all user p
51. rkstation Hardware Manual Operating System CTOS Operating System Manual System Programmer s Guide Guest Operating Systems CP M 86 MS DOS and GW BASIC XENIX Programming Languages COBOL Manual FORTRAN Manual FORTRAN 86 Manual BASIC Manual BASIC Compiler Manual Pascal Manual Assembly Language Manual Documentation Guide vii Program Development Tools COBOL Animator Editor Manual Debugger Manual Linker Librarian Manual Data Management Facilities CT DBMS Manual ISAM Manual Forms Manual Sort Merge Manual Text Management Facilities Word Processing User s Guide Word Processing Reference Manual Word Processing Quick Reference Applications Facilities Project Planner Manual CT MAIL User s Reference Manual CT MAIL Administrator s Reference Manual Multiplan Business Graphics User s Guide Business Graphics Reference Manual Graphics Programmer s Guide Font Designer Manual Communications Asynchronous Terminal Emulator Manual 3270 Terminal Emulator Manual 2780 3780 RJE Terminal Emulator Manual SNA Network Gateway Manual SNA 3270 Emulator Manual X 25 Network Gateway Manual Multimode Terminal Emulator User s Guide Multimode Terminal Emulator Reference Manual This section outlines the contents of these manuals INTRODUCTORY The Installation Guide describes the procedure for unpacking cabling and powering up a system The Operator s Guide addresses the needs of the average user for operating instructi
52. rocesses 2 When you press the CODE key and the GO key at the same time after typing an Executive command or when using the Context Manager 3 When a process reaches a previously placed breakpoint 4 When you press the ACTION key and the B key at the same time In this mode the Debugger suspends only the user processes that reach a breakpoint all other user processes that are running continue to run 5 When a process executes a DEBUG instruction INT 3 advanced debugging The Debugger interprets keystrokes in a way that minimizes accidental invocations of the Debugger or termination of the process being executed For example pressing the ACTION key has no effect unless you press one of three other keys A B or FINISH simultaneously Getting Started with the Debugger 3 1 DEBUGGER PROMPTS Whenever you are using the Debugger the screen shows your most recent dialogue with the Debugger and also shows a Debugger prompt The Debugger prompt is an asterisk a pound sign a Space a percent sign or an exclamation mark or a greater than sign gt depending on the type of debugging you are doing These prompts are discussed in more detail in subsequent Sections of this manual However their meanings are listed below the Debugger has suspended the current process the Debugger has not suspended the current process the Debugger is at an interrupt level the Debug File utility is in
53. rs CB and DB The following paragraphs explain how to do so To display a block of memory that is k bytes long and that has a link word at the jth byte you should first set CB equal to k and then set DB equal to j For example CB gt 0000 8 DB 0000 To display the first block type addr CODE N To display each subsequent block again type CODE N Or to display n blocks at the same time type n addr CODE N where n is a decimal number For example 3 1217 3084 CODE N specifies that three blocks are to be displayed at once A typical Debugger response appears below 1217 3084 02 31 Cl 01 7C 3E AF 17 1217 3102 DA 31 83 80 68 26 76 5D 1217 31DA 00 00 C1 FF 04 4C 17 12 Advanced Display Commands 13 1 CODE S DISPLAYING THE STATUS OF PROCESSES AND EXCHANGES Processes communicate with one another by sending messages to exchanges The two primitives used are SEND and WAIT An exchange can be occupied by a message or by a process that is waiting to receive a message The CODE S command displays the status of processes and exchanges To obtain a display of all of the processes and exchanges type CODE S When you enter CODE S the Debugger displays an entire screen of information The first item is a listing of processes as shown in Figure 13 1 below Processes id oPcb cs i oExtPcb 00 3084 0045 1 3184 01 3096 1075 1 3196 02 30A8 09DC 1 31A8 03 30BA 06FC 31BA 04 30CC 06F0 1 31cc 05 30DE 093D 1 31DE
54. rwise terminated only the breakpoints in that partition are removed To obtain a display of a list of all of the breakpoints that are set at any given time type CODE B without an address parameter This activity is known as querying the breakpoints Using Breakpoints 5 1 CODE C CLEARING BREAKPOINTS To clear a breakpoint type a parameter followed by CODE C For example to clear the breakpoint at address addr type addr CODE C To clear all of the breakpoints at once type CODE C without an address parameter CODE A SETTING CONDITIONAL BREAKPOINTS A conditional breakpoint is a breakpoint that is associated with a relational condition When a process reaches a conditional breakpoint the process is suspended only if the relational condition is evaluated as TRUE To set a conditional breakpoint type a parameter and CODE A Two examples appear below To set a breakpoint at physical address 0E0 3B1 type 0E0 3B1 CODE A To set a conditional breakpoint at symbolic address Accept 23 type Accept 23 CODE A You define the relational condition by entering code into the Debugger s patch area The patch area is a 50 byte space addressed by the symbol PatchArea To enter code type PatchArea MARK The Debugger then displays the first instruction in the patch area For example a typical Debugger response appears below PatchArea h NOP 5 2 Debugger Manual At the end of this line the Debugger displays the
55. sary 2 Debugger Manual Public symbol An ASCII character string associated with a public variable a public value or a public procedure Public variable Variable whose address can be referenced by a module other than the module in which the variable is defined Public value Value whose address can be referenced by a module other than the module in which the value is defined Public procedure Procedure whose address can be referenced by a module other than the module in which the procedure is defined Register mnemonic Two letter symbolic name for a register in the 8086 80186 processor for example AX BL SI Run file File created by the linker The run file contains the initial image of code and data for a program Run file checksum word Number produced by the summation of words in a run file Used to check the validity of the run file Segment A discrete portion of memory of a routine or of a program Segment address Address of a segment base For an 8086 80186 microprocessor a segment address refers to a paragraph 16 bytes Segmented address pointer Address that Specifies both a segment base and an offset Segment override Operating code that causes the 8086 80186 to use the segment register specified by the prefix when executing an instruction instead of the segment register that it would normally use Set Place a breakpoint at a particular location in memory Simple mode Debugger operati
56. section in Section 3 Getting Started with the Debugger o If a location is open then the Debugger prompts you with an empty space This prompt appears on the same line as the value of the open location CODE D DISPLAYING THE CONTENTS OF MEMORY The CODE D command lets you display the contents of memory in both numerical and ASCII form CODE D takes two parameters and can display a number of bytes of memory along with ASCII equivalents of those bytes limited only by the amount of memory present in the machine The Debugger displays the memory content in columns Examining and Changing Memory Contents 4 3 For example to display a specific number of bytes of memory starting at a specific memory location type k addr CODE D where k is the number of bytes and addr is the memory location For example to display 9 bytes of memory starting at memory location 38DD type 9 38DD CODE D A typical Debugger response is shown below 38DD 18 83 C3 52 80 3F 00 74 05 c s n The material displayed at the right of this re Sponse indicates the ASCII characters that these bytes represent The Debugger automatically turns off the symbolic display of addresses while memory contents are being displayed CHANGING THE CONTENTS OF A MEMORY LOCATION When a location is open and the Debugger prompts you with a space you can change the contents of that location by typing the new contents that you want For example su
57. so enter the Debugger in simple mode by using the Chain or LoadTask operations of standard software See Section 7 of the CTOS Operating System Manual for details of this advanced procedure In this mode all user processes are suspended when you or the program enters the Debugger This mode does not affect operating system services or interrupt handlers The nonresident portion of the Debugger can swap in and out of memory However this procedure requires no intervention by the user and is not evident to the user Simple mode requires approximately 55K bytes less physical memory than the multiprocess mode or the interrupt mode In simple mode the Debugger prompt is an asterisk Debugger Modes 8 1 MULTIPROCESS MODE You invoke this mode by pressing ACTION B This mode also occurs when a CODE B breakpoint is executed after ACTION B invokes the Debugger All user processes continue execution after you enter the Debugger The Debugger suspends only those user processes that have reached a breakpoint This mode does not affect operating system services or interrupt handlers It is most useful for debugging certain real time programs such as the timer process in the Executive If you invoke the Debugger by entering the ACTION B command then you can still type ACTION A to invoke the Debugger in its ACTION A mode and suspend all user processes However once you invoke the Debugger in ACTION A mode you cann
58. structure and system operation It describes 1 cluster architecture and operation 2 procedures for building a customized operating system and 3 diagnostics GUEST OPERATING SYSTEMS The CP M 86 and MS DOS Manuals describe the single user operating systems originally designed for the 8086 based personal computer systems The GW BASIC Manuals describe the version of BASIC that runs on the MS DOS Operating System The XENIX Manuals describe the 16 bit adaptation of the UNIX system including the XENIX envi ronment for software development and text processing PROGRAMMING LANGUAGES The COBOL FORTRAN FORTRAN 86 BASIC Inter preter BASIC Compiler PASCAL and Assembly Language Manuals describe the system s program ming languages Each manual specifies both the language itself and also operating instructions for that language The Pascal Manual is supplemented by a popular text Pascal User Manual and Report The Assembly Language Manual is supplemented by a text the Central Processing Unit which de Scribes the main processor the 8086 It speci fies the machine architecture instruction set and programming at the symbolic instruction level PROGRAM DEVELOPMENT TOOLS The COBOL Animator describes the COBOL Animator a debugger that allows the user to interact directly with the COBOL source code during program execution The Editor Manual describes the text editor
59. t Merge object modules that can be called from an application program TEXT MANAGEMENT FACILITIES The Word Processing User s Guide introduces the Word Processor to the first time user It provides step by step lessons that describe basic word processing operations The lessons show how to execute operations and apply them to sample text Documentation Guide xiii The Word Processing Reference Manual is a reference tool for users already familiar with the Word Processor It describes the Word Processor keyboard and screen basic advanced and programmer specific operations list processing printer and print wheel configurations and hardware considerations The Word Processing Quick Reference provides a concise summary of all word processing operations and briefly describes the keyboard and commands APPLICATIONS FACILITIES The Project Planner schedules and analyzes tasks milestones and the allocation of resources in a project By means of diagrams and several kinds of bar charts Project Planner presents time and resource allocation results and shows the occurrence of project milestones The Project Planner Manual explains the use of the program and also serves as a reference once the user is familiar with it The CT MAIL User s Reference Manual introduces the first time user to the CT MAIL electronic mail system It provides step by step instructions for using the basic CT MAIL operations to create
60. then In this case the Debugger returns 2048 which is the decimal equivalent of 800h For more information about CODE R see the CODE R Changing the Number Base subsection below CODE F OPENING A SYMBOL FILE The Linker produces symbol files that contain the addresses of public symbols See the Linker Librarian Manual for more information about the Linker One symbol file usually exists for each run file or for each user task The Debugger cannot refer to a symbol file unless you open the symbol file first To open a symbol file type filename CODE F A file name consists of text constants and must be enclosed in single quotation marks For example suppose you want to debug a program called Getting Started with the Debugger 3 3 Graph Run If the corresponding symbol file is lt Jones gt Graph Sym then you would type lt Jones gt Graph Sym CODE F The CODE F command opens the symbol file for your program and gives you access to the public symbols in the symbol file The Debugger can refer to only one symbol file at one time When you type filename CODE F the Debugger ignores any previously opened symbol files A user program usually has only one symbol file It is good practice to open the symbol file when you begin a debugging session thereafter you can use its symbols freely until you terminate the program or end the debugging session When a symbol file is open the Debugger uses it to prov
61. ts the current process at addr CODE H Invokes the histogram facility param CODE H Specifies the bucket size for the histogram facility param CODE H Specifies the range for param the histogram facility Command Summary B 1 addr addr k addr lower addr upper addr byte pattern Im B 2 Debugger Manual CODE I CODE I CODE K CODE L CODE N CODE N CODE N CODE O CODE O CODE P CODE P CODE P CODE Q CODE Q CODE R Displays a list of all breakpoints Sets a breakpoint at addr in interrupt mode Exits from and deactivates the Debugger Turns printer echo ON and OFF Displays the next entry in a linked list Displays the first entry in a linked list Displays k entries in a linked list Searches for byte pattern Starting at lower addr Searches for byte pattern Starting at new lower addr Proceeds from the current breakpoint Proceeds k times from the current breakpoint Proceeds after removing the current breakpoint Displays the range and bucket size for the histogram facility Displays the report created by the histogram facility Sets the output radix to hexadecimal or to decimal if the current radix is hexadecimal k k k addr k addr addr k addr addr k addr value expression or instruc tion CODE R CODE S CODE S CODE T CODE T CODE U CODE X CODE Z CODE CODE CODE CODE MARK MARK Sets
62. upt mode Debugger operating mode used to debug interrupt handlers or to set breakpoints in the Operating System Kernel Link word Word address i e a 16 bit address pointing to the next block of data Linked list data structure Data structure containing elements that are linked by 16 bit addresses link words or by 32 bit addresses link pointers The CODE N command uses link words Linker Software system that loads and connects together the object programs output separately by a compiler or assembler BASIC FORTRAN et al and from them produces a run file Multiprocess mode Debugger operating mode used in debugging a user task that involves more than one process and that depends on continuous execution of all processes except the ones stopped at breakpoints Offset The number of bytes by which a memory location is distant from the beginning of a segment Output radix The base of the notation in which Debugger output is expressed binary decimal hexadecimal or any other base from 2 to 16 inclusive Parameter A constant number port or text a symbol or one or more unary or binary operators address expressions or symbolic instructions Physical address An address that does not Specify a segment base and is relative to memory location 0 Pointer See segmented address below Port constant Number followed by an i or an o indicating an input port and an output port respectively Glos
63. urn off the histogram facility enter CODE H again with no parameters as shown below CODE H The Debugger responds by displaying the following message Histogram Off After turning off the histogram facility you can change the bounds and the bucket size and invoke the histogram facility again as explained above 11 4 Debugger Manual 12 BREAKPOINTS IN INTERRUPT HANDLERS The breakpoint commands described in Section 5 Using Breakpoints let you place breakpoints in normal user code and in normal operating system code However these commands alone cannot place a breakpoint in the operating system kernel or in an interrupt handler CODE I SETTING BREAKPOINTS IN INTERRUPT HANDLERS To set a breakpoint at address addr in an interrupt handler or in the OS kernel type addr CODE I The standard keyboard and video facilities of the operating system support your interaction with the Debugger except when the OS kernel or an interrupt handler is broken At these breakpoints all processes including OS processes are suspended and the Debugger then works by direct access to the physical keyboard and the screen CODE I breakpoints are prohibited if the Debugger has swapped out a part of the user program The Debugger does this when the user program and the Debugger together are too large to fit in the partition Before exiting from interrupt mode you should explicitly remove any CODE I breakpoints by entering th
64. ut how to use the Debugger s multiprocess mode how to enter the mode how to proceed and how to switch control of the keyboard and the video display between the user process and the Debugger ENTERING MULTIPROCESS MODE VIA ACTION B As noted in Section 8 you enter multiprocess mode by pressing ACTION B If you have invoked the Debugger using ACTION B then multiprocess mode is also entered when a CODE B breakpoint is executed PROCEEDING CODE P AND EXITING In multiprocess mode if the current process has been suspended the CODE P command causes that process to resume However in multiprocess mode the CODE P command does not exit from the Debugger As noted above you press CODE P to proceed with the current process without exiting from the Debugger To exit you must press GO Similarly you press CODE G to begin process execution at a different address from the one at which the process stopped Pressing CODE G does not exit from the Debugger KEYBOARD AND VIDEO SWAPPING In multiprocess mode pressing GO does not cause the currently interrupted process to proceed Instead in this mode you press GO to exit the Debugger and return control of the screen and the keyboard to the user process Using Multiprocess Mode 9 1 10 SWAPPING OVERLAYS AND PORTS This chapter describes how the Debugger manages memory explains how to examine code in an overlay and discusses how to read and write to ports DEBUGGER
65. utput port Examples of port constants appear below 12i is the input port that has port address 12 0A20 is the output port that has port address 0A2 The Debugger can both read and write an input port constant However the Debugger never reads an output port constant The and commands open output ports for modification without reading them Concepts 2 3 TEXT A text constant is a sequence of characters en closed by single quotation marks To include a single quotation mark in a text constant you should type another single quotation mark in front of the mark to be enclosed For example abed is the four character text constant abed iu is the two character text constant a consisting of a single quotation mark and the letter a Text constants consisting of one or two charac ters can be used wherever a number a numeric constant can be used However text constants consisting of more than two characters can be used only with the CODE F and CODE O commands described in sections 3 and 4 respectively SYMBOLS A symbol is a sequence of alphanumeric and special characters A symbol must begin with an alphabetical character it cannot begin with a digit The special characters are the underscore the period the dollar sign the percent sign 3 the pound sign and the exclamation mark 1 The Debugger recognizes the following four types of symbols o User defined public s
66. wer addr type CODE O with no parameters In either case if the Debugger does not find a byte pattern then the Debugger ends the search when it reaches upper addr 4 6 Debugger Manual Table 4 1 Examples of Byte Byte Pattern 30 31 32 ABC 30 31 32 ABC 33 34 35 Patterns Pattern Specified 123 ABC 123ABC456 Examining and Changing Memory Contents 4 7 5 USING BREAKPOINTS A breakpoint is a user defined location in code When a process reaches a breakpoint the process is suspended and the Debugger is entered If the Debugger is operating in simple mode all user processes are suspended whenever any breakpoint is taken If the Debugger is in multi process mode only the process that has taken the breakpoint is suspended See Section 8 for a detailed description of the Debugger s operating modes and Section 12 for an explanation of OS debugging using CODE I to set breakpoints in interrupt handlers CODE B SETTING AND QUERYING BREAKPOINTS To set a breakpoint type CODE B preceded by one parameter For example to set a breakpoint at the address addr type addr CODE B You can enter CODE B to set a breakpoint in an overlay even if the overlay is not present in memory A breakpoint stays in effect until you remove it explicitly by entering the CODE C command described below or until the process terminates When a program in a memory partition calls CHAIN or EXIT or is othe
67. y of operation of the printed circuit boards Motherboard Deflection 8088 CPU 8086 CPU Floppy Disk Controller and Hard Disk Control ler keyboard video monitor cluster communica tions interface external interfaces power supply and environmental characteristics of the workstation The AWS Color Workstation Hardware Manual de Scribes the mainframe keyboard and color video display of the AWS Color Workstation This manual reports the architecture and theory of operation of the printed circuit boards Motherboard Graphics Control Board Hard Disk Controller Color Video Color Deflection and CPU keyboard color monitor peripheral interfaces cluster communications interface power supply and environmental characteristics of the workstation This manual also contains four OEM disk drive manuals and a summary of adjustments for the color monitor OPERATING SYSTEM The CTOS Operating System Manual describes the operating system It specifies services for managing processes messages memory exchanges tasks video disk keyboard printer timer communications and files In particular it specifies the standard file access methods SAM the sequential access method RSAM the record sequential access method and DAM the direct access method The System Programmer s Guide addresses the needs of the system programmer or system manager for Documentation Guide xi detailed information on operating system
68. ymbols such as those in a symbol file produced by the linker from a source program See the Linker Librarian Manual o Standard 8086 80186 register mnemonics such as AX BL and SI o Names of Debugger state variables such as the process register PR See Section 6 below o The period indicates the value of the Segment and offset for the most recently opened location 2 4 Debugger Manual For examples of symbols see the Address Expres sions subsection below ADDRESS EXPRESSIONS Address expressions in the Debugger have the same Structure and semantics as address expressions in assembly language Examples of address expres sions appear below RgParam represents the simplest address expression a symbol RgParam 100 2 is a more complex address expression involving a symbol BX 5 is an indexed address expression ES BX 5 SI is a doubly indexed address expression having a segment override prefix SYMBOLIC INSTRUCTIONS Symbolic instructions in the Debugger have the same structure and semantics as they do in as sembly language except that symbolic instruc tions Cannot include user defined public symbols Examples of symbolic instructions appear below MOV AX WORD PTR BX 5 LOCK INC BX CURRENT VALUE The Debugger remembers a special value known as the current value The current value is either the value most recently displayed by the Debug ger or the value that you typed most
69. you modify a run file the utility automat ically corrects the run file checksum word D 2 Debugger Manual APPENDIX E OPERATING NOTES DUAL FLOPPY DISK SYSTEMS When a system is booted the Debugger tries to create a file called Sys DebuggerSwap Sys This file requires 74 free sectors on the disk If you want to use the Debugger on a dual floppy disk system the system disk must contain the file called lt Sys gt Debugger Sys This file must not be write protected because if it is the Debugger cannot create its swap file You must enter a CODE K command to the Debugger before removing the system disk from the drive CLUSTER SYSTEMS Before using the Debugger on a cluster system either from the master workstation or from one of the cluster workstations you should follow carefully the cluster software installation procedure described in the Release Notice DEBUGGER FILES The Debugger has different file names depending on the type of workstation The Debugger file must be in the system directory Sys lt Sys gt The Debugger file names are listed below o IWS Debugger Sys o AWS Debugger Sys o N GEN T1 DebuggerTl Sys When the Debugger initializes itself it creates a file called DebuggerSwp Sys in the lt gt directory Operating Notes E 1 GLOSSARY Address expression Description of a location in memory The description consists of one or more symbols or an indexed or nonindexed parameter

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