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1. Before Address Contents 009000 1234 009002 5678 009004 OABC 009006 0000 After Address Contents 009000 1234 009002 5678 009004 OABC 009006 7368 Note 1234 5678 SOABC 7368 40 The sample conditions show the source data and the memory location where the result is stored The result of the addition is shown in the after contents of memory location 9006 This allows the programmer to work through the problem by hand to verify the objective Below is one possible solution to this problem Solution kkkxkxkxk xkxkxk xkxk xkxkxk x xkxk x xk kxk x xk kxk x xkxk x xk kx x xk kxk x xk kxk x xk kxk kxx xk kxk xx xk kxk xk xkx xk kxk kxk xx xxk xx xx 2 EXAMPLE SRC a 3 KKK KKK KKK KKK KKK KKK KKK KKK KKK KKK KKK KKK KKK KKK KKK KKK KKK KKK 4 00008000 CODE EQU 8000 5 00009000 DATA EQU 9000 6 7 00008000 ORG CODE 8 00008000 207C0000 EXAMPLE OVEA L NUMBERS AO use AO as pointer 00008004 9000 9 00008006 323C0003 OVE W COUNT D1 juse D1 as counter 10 0000800A 4240 CLR W DO j init DO 0 11 0000800C D058 LOOP ADD W A0 D0 12 0000800E 5341 SUBQ 1 D1 13 00008010 66FA BNE LOOP 14 00008012 3080 OVE W DO A0 15 00008014 4E4E TRAP 14 16 17 00009000 ORG DATA 18 00009000 1234 NUMBERS DC W 1234 19 00009002 5678 DC W 5678 20 00009004 OABC DC W SOABC 21 00000003 COUNT EQU NUMBERS 2 22 00009006 0000 SUM DC W 0
2. C 68KMB gt PC VT When PC VT begins executing it briefly displays a copyright screen then it enters terminal emulation mode Several important command key sequences are displayed on the screen including the key sequence to obtain help Access PC VT s help screen by pressing ALT H PC VT includes twelve screens of help Browse through these by pressing PgDn or PgUp As you can see PC VT supports many advanced features Most of these pertain to the special keyboard definitions on a VT 100 terminal or the other terminal types supported by PC VT We will only use a small subset of PC VT s features in this and subsequent labs Leave help and return to terminal emulation mode by pressing the ESCAPE key It may be necessary to re configure PC VT to operate with a different COM port at a different baud rate or with a different data format PC VT includes two setup screens to customize its operation for a particular application Access PC VT s SETUP A screen by pressing 13 10 11 12 CTRL F1 Proceed to SETUP B by entering 3 The screen shows all the configuration modes that we are concerned with Change the baud rate by continually entering 7 The changes are highlighted near the bottom of the display Cycle through the baud rates until 9600 is selected Change the data format by continually entering E The changes are observed beside the baud rate display The first character of the display indicates the
3. C 68KMB gt Find the names of hexadecimal files in the current directory by entering C 68KMB gt DIR HEX Make a mental note of the name of one of the files Files with HEX as the filename suffix contain Motorola S records representing the binary bytes of a 17 21 22 23 68000 program The format of Motorola S records is discussed in Chapter 1 of your textbook Return to terminal emulation mode by entering C 68KMB gt EXIT Issue a File Transmit command to PC VT on one system by entering CTRL F4 When the file dialog box appears enter XXXX HEX where xxxx is the name of a hexadecimal file from step 20 The content of the file is transmitted out the COM port and appears on the screen of the other system Enter Y when asked if CTRL Z should be transmitted Repeat this operation from the other system Note If a large file is transmitted it is possible that the receiving system will experience a buffer overflow This will only occur on systems which are too slow to receive continuous input at 9600 baud e g a 12 MHz PC AT PC VT responds by displaying hash characters when its buffer overflows Note that the 68KMB is capable of receiving continuous input at 9600 baud Buffer overflows should they occur will not compromise the operation of the 683KMB when using PC VT in subsequent labs Illustrate to your lab instructor that the two systems are communicating with each other and that files ca
4. Good luck PROCEDURE 1 The example program called FIRMWARE is found in the 68KMB directory on the PC host computer The listing appears in Figure 15 2 at the end of this lab Obtain two blank 2764 or 2764A EPROMs from your lab instructor 106 CAUTION A 2764 is not the same as a 2764A Use the EPROM programming software to select the correct type of EPROM Programming a 2764A as a 2764 will destroy the device Burn this program into an upper byte EPROM and a lower byte EPROM Install the EPROMs in the user sockets on the 68KMB Test the program two ways first by entering the MON68K command GO 4000 then by installing jumper X16 and pressing the RESET switch Demonstrate the program to your lab instructor 15 1 Note Jumpers X5 through X11 on the 63KMB configure the size and type of device installed in the user sockets The following jumpers are required for 2764 or 2764A EPROMs X5 X6 X7 X8 X9 X10 X11 jumper no jumper jumper no jumper no jumper jumper no jumper 2 Make the changes described earlier to the ECHO program While debugging the new program leave its execution address at 008000 as in lab 14 Demonstrate to your lab instructor that ECHO3 is executing correctly in RAM 15 2 107 3 Modify ECHO3 XLK placing the EPROM code segment at address 0 Re link the program and burn it into EPROM Install jumper X16 and demonstrate the program to your lab instructor 15 3 4 OPTIONAL Under
5. MOVE W D0 D1 make a copy of n in D1 ADDQ W 1 D1 add 1 to n store result in Dl ADD W D0 D1 add n to result ADD W 9 D1 add 9 to result DIVU W 2 D1 divide result by 2 SUB W DO D1 subtract n from result TRAP 14 return to MON68K Use the R command to initialize data register DO with a data value of 00000015 v4 4 gt D0 15 Verify the new value in DO using the register display command V4 4 gt RD Prepare to execute the program by initializing the 68000 s program counter with 008000 V4 4 gt PC 8000 The command above is a variation of MON68K s R X command See Appendix E of your textbook for details Verify the new value in the program counter by using the register display command V4 4 gt RD Execute the program using MON68K s GO command v4 4 gt GO 26 15 16 The program executes and terminates by returning to MON68K What is the final result in D1 Now we ll execute the program again in single step mode This is a very powerful debugging feature of MON68K Enter V4 4 gt D0 15 V4 4 gt PC 8000 V4 4 gt TR 1 MONO68K s trace TR command is similar to the GO command except the instructions are executed one at a time and the CPU s registers are displayed after each instruction As well the instruction that will execute next is displayed With a parameter of as above TR executes one instruction and then waits for user input Continue to single step through the program by
6. 1 or that the receive buffer is empty RxRDY 0 Both TxRDY and RxRDY are status flags that are checked through software to determine the status of an input or output port Character Reception When inputting a character RxRDY must be interrogated continually i e in a loop until it equals 1 This indicates a character has been received and is sitting in the receive FIFO waiting to be read After reading the character RxRDY is cleared automatically unless there is another character in the FIFO waiting to be read A flowchart of the steps just described is shown in Figure 6 3a 53 Read RxRDY Flag Character Wait ing Read Character Clear Flag m Figure 6 3 Flowcharts for a character input and b character output a Re ad TxRDY Flag Write Character Clear Flag b The instructions to input a character from the terminal computer attached to the 68681 into register DO are shown below DUART EQU 00C001 SRA EQU 2 RBA EQU 6 MOVEA L DUART AO LOOP MOVE B SRA A0 ANDI B 1 D7 BEQ LOOP MOVE B RBA AO DO base address for 68681 offset for Status Register A offset for Receive Buffer A AQ points to 68681 get Status Register A RxXRDY 1 no check again yes input character Note the effective use of equates to make the instructions easier to understand As well the addressing mode used to access the 68681 registers is address register indirect with
7. 5 3 45 Problem 3 Write a program called SAME to compare two strings of ASCII characters to see if they are the same The starting addresses are contained in the longword variables START1 at location 9000 and START2 at location 9004 The first byte of each string contains the string length in bytes and is followed by the string If the two strings match clear the variable MATCH at location 9008 otherwise set its value to 1 Sample Conditions Before Address Contents 009000 0000 009002 9040 009004 0000 009006 9050 009008 5399 009040 0441 009042 4243 009044 44FF 009050 0441 009052 4244 009054 5FDD After 009008 FFFF 1 Strings are different Note Test your program with several different string conditions Place strings in your program in the appropriate way mia 46 Problem 4 Write a program called HEXCHAR to convert the contents of the variable HEX at location 9000 to an ASCII character representing the hexadecimal value of the variable HEX contains a single hexadecimal digit the four most significant bits are zero Store the ASCII character in the variable CHAR at location 9001 Sample Conditions Before Address Contents 009000 OFO0O After 009000 OF 46 Note Verify that your program works for any hexadecimal value 5 5 47 Problem 5 Write a program called LOOKUP to convert the contents of the BCD variable DIGIT at location 9000 to a seven segment code and store it in the var
8. from the console and displays the ASCII code in binary on the LEDs Put the program in a loop and terminate to MON68K when q is detected Put your name and the date in comment lines at the top of the source program Demonstrate KEYTEST to your lab instructor 74 An example program called TWOHZ is presented in Example 9 5 in your textbook The program makes LED 3 flash at a rate of 2 Hz Unlike Example 9 4 which uses a software delay to synchronize output TWOHZ uses the 68681 s built in timer Review the software listing and the description of the program to gain an understanding of its operation 63 Run TWOHZ and demonstrate it to your lab instructor 7 5 9 Write a modified version of TWOHZ that causes all 8 LEDs to flash at a rate of 5 Hz Call the new program FIVEHZ Continue to use the 68681 timer in FIVEHZ A new approach is required however In Example 9 5 we directed the timer output to OP3 by writing 04 to the output port configuration register This will not work here because we want all 8 LEDs to flash The solution is to interrogate the timer status directly to determine when the counter reaches its terminal count Each time the terminal count is reached the output data should be complemented Note It takes two toggles of the output data to achieve one period of flashing The terminal count is tested through the counter timer ready bit of the interrupt status register ISR See Chapter 9 Table 9 2 and Appendix
9. ANDI B 4 D7 TXRDY 1 BEQ LOOP no check again MOVE B DO TBA A0 yes send character PROCEDURE 1 Make a copy of MYNAME SRC from lab 4 and save it in a file called MYNAME2 SRC Put your name and the data in comment lines at the top Modify the new program as follows Place the code to output a character to the terminal in a subroutine called OUTCHR This subroutine should be called from inside the subroutine OUTSTR Do not use trap instructions except at the end of the program to return to MON68K Use equates near the top of the source program to define symbols for the 68681 registers Use these symbols as appropriate in your subroutine 55 Obtain a printout of the listing file and show it to your lab instructor Demonstrate your program 6 1 Write a program called ALPHA that outputs a continuous stream of alphabetic characters to the terminal as follows abcdefghijkimnopqrstuvwxyz abcdefghijkimnopqrstuvwxyz abcdefghijkimnopqrstuvwxyz etc Monitor the keyboard for input as follows e If U or u is entered the output switches to uppercase e If L or l is entered the output switches to lowercase e If Q or q is entered the program terminates to MON68K e Ignore any other input characters Do not use trap instructions except at the end of the program to return to MON68K Put your name and the date in comment lines at the top Demonstrate the program to your lab instructor 6 2 CONCLUSION This l
10. Development 3a5 ssesscascasadaaseasedinadavedaavegoasa adorns daseean cagaassacanvess uanss 100 Appendix A Checkout Calibration for I O Board 6 000 0 eeeesseeeeeseneeeeeeesneeeeeeeaaes 109 Introduction The following labs are intended for educational use in college or university courses using The 68000 Microprocessor textbook and the 68KMB single board computer The complete set of materials for these labs consists of e The 68000 Microprocessor textbook e 68KMB 68000 based single board computer from URDA Inc e I O Board 1 from URDA Inc e I O Board 2 from URDA Inc e I O Board 3 from URDA Inc e I O Board 4 from URDA Inc e I O Board 5 from URDA Inc e I O Board 6 from URDA Inc e PC host computer with COM port e screwdriver e oscilloscope e voltmeter e null modem cable e 12 volt or 15 volt power supply e amplified speaker system Note that the 68KMB is shipped complete with serial cable AC adapter two 20 conductor ribbon cables and a user s manual The 68000 Microprocessor textbook is shipped with a 3 5 inch 1 44M byte student disk containing the following e 68000 cross assembler A68K e Linker locator XLINK e Batch files to simplify execution of A68K and XLINK e Terminal emulator PC VT e Example programs from The 68000 Microprocessor textbook An instructor disk is also available This disk contains solutions to all problems given in the following labs Contact UR
11. FF to Data Direction Register A DDRA at address 010001 Hint Use MON68K s memory modify command c Enable access to Port A of the 6821 by writing 04 to Control Register A CRA at address 010003 d Write FF to Port A at address 010001 This places the byte FF at the input to the MC1408L8 DAC generating the full scale output voltage at Test Point 1 TP1 see Figure 12 1a e Adjust trimpot R1 while observing the voltage at TP1 Calibrate for a full scale output of 10 volts 84 5 Write the following values to the DAC and measure the analog result with an oscilloscope Tabulate the results 00 7F 80 BO FF Demonstrate to your lab instructor that you can configure the 6821 PIA using MON68K s memory modify command and manually write data to the MC1408L8 DAC 12 2 6 A program called SAWTOOTH is presented in Example 9 13 in your textbook The program creates a sawtooth waveform at TP1 by continually sending a count to the DAC Review the software listing and the description of the program to gain an understanding of its operation The program is in the directory 68KMB on the PC host computer Run the program and demonstrate it to your lab instructor What is the frequency of the sawtooth waveform that you observe on the oscilloscope What is the duration of each output step 7 Use MON68K s DI command to disassemble the program Compare the result with the listing in y
12. R S232C serial interface cable e 20 conductor ribbon cable 70 MS DOS Software e A68K 68000 cross assembler e XLINK 68000 linker locator conversion utility e PC VT VT100 terminal emulator e EDIT MS DOS text editor or equivalent 68000 Programs e COUNT4 provided in 68KMB directory e COUNT4D to be written INTRODUCTION This is the third in a series of labs to explore interfacing with the 68KMB I O Board 3 is a simple interface between the 68681 on the 68KMB and a 4 digit output display The output consists of four 7 segment LED displays driven by an MC14499 As shown in Figure 9 1 only three 68681 output signals are required to interface to the MC14499 J1 5 V 20 pin header DATA CLOCK ENABLE MC1 4499 IC1 h dp D4 D3 D2 D1 Figure 9 1 I O Board 3 The interface is described in detail in The 68000 Microprocessor Section 9 8 Review this before proceeding 71 PROCEDURE 1 With the 68KMB powered off connect I O Board 3 to J1 2 Power on the 68KMB and the PC host computer Execute PC VT and obtain the MONO68K prompt from the 68KMB 3 An example program called COUNT4 is presented in Example 9 9 in The 68000 Microprocessor COUNT4 outputs a 4 digit count to the MC14499 The count increments at 10 Hz beginning at 0000 and overflowing at 9999 Review the software listing and the description of the program to gain an understanding of its operation The program is in the directory 683KMB o
13. SAWTOOTH e TRIANGLE e SINEWAVE e AMAJOR INTRODUCTION This is the sixth in a series of labs to explore interfacing with the 68KMB I O Board 6 contains a single 6821 PIA and two separate interfaces Port A of the PIA interfaces to an 8 bit digital to analog converter DAC and Port B of the PIA interfaces to an 8 bit analog to digital converter ADC The DAC is an MC1408L8 device and the ADC is an VT100 terminal emulator 68000 cross assembler 68000 linker locator conversion utility provided in 68KMB directory to be written provided in 68KMB directory provided in 68KMB directory ADC0804 device This lab is concerned with the DAC interface The complete schematic of I O Board 6 is spread over three pages These appear in Figure 12 1 at the end of this lab Note that I O Board 6 requires an external 12 volt or 15 volt power supply The DAC interface is discussed in Section 9 13 of your textbook Review this before proceeding 83 PROCEDURE 1 With the 63KMB powered off connect I O Board 6 to J2 With the external power supply switched off connect the power supply cable to I O Board 6 Have your lab instructor verify the connections before turning the power on 12 1 Power on all equipment and execute PC VT on the PC host computer The monitor prompt should appear on the console Calibrate the MC1408L8 as follows a Reset the 683KMB b Configure Port A of the 6821 as an output port by writing
14. The easiest way to do this is to press the down arrow key followed by the up arrow key until the desired memory address is displayed in the current line Note Do not write data to address CO1B This will re configure the output port and foul up subsequent access to the 68681 To restore the 68681 to its default configuration press the 68KMB s reset switch Use MON68K s commands to write to OPR_CLR and OPR_SET to turn LEDs on and off Demonstrate to your lab instructor that you are comfortable using MON68K commands to read the input switches and write to the LEDs 7 1 An example program called WIRE681 is presented in Example 9 3 in your textbook WIRE681 simulates a wire connection between the six input switches and the six least significant LEDs Review the software listing and the description of the program to gain an understanding of its operation 62 WIRE681 and other examples from your textbook are located in the 683KMB directory of drive C on the PC host computer Run the program and demonstrate it to your lab instructor Be prepared to answer questions on the operation of this program 71 2 Another example program called ROTATE is presented in Example 9 4 in your textbook Review the software listing and the description of the program to gain an understanding of its operation Run the program and demonstrate it to your lab instructor 7 3 OK now it s your turn Write a program called KEYTEST that inputs characters
15. e XLINK e PC VT e EDIT 68000 Programs e LED7 e LEDSHZ e LED7A e RSEGMENT INTRODUCTION 68000 cross assembler 68000 linker locator conversion utility VT100 terminal emulator MS DOS text editor or equivalent provided in 68KMB directory provided in 68KMB directory to be written to be written This is the second in a series of labs to explore interfacing with the 68KMB I O Board 2 is a simple interface between the 68681 on the 683KMB and a 7 segment display and four switches The schematic is illustrated in Figure 8 1 66 MAN7 2A 7 segment common anode LED To Ji onthe 68KMB SW3 SW2 SW1 swo Figure 8 1 I O Board 2 I O Board 2 is very similar to I O Board 1 Instead of six input switches I O Board 2 only has four These are used to input a 4 bit BCD or hexadecimal code The output LEDs are combined in a 7 segment display driven by OPO OP6 A decimal point LED is driven by OP7 Electrically the interface to the LEDs 1s identical to that in I O Board 1 PROCEDURE 1 With the 68KMB powered off connect I O Board 2 to J1 2 Power on the 68KMB and the PC host computer Execute PC VT and obtain the MONO68K prompt from the 68KMB 67 Use MON68K s memory modify command to access the 68681 s output port registers Experiment with turning on the segments of the LED display one at a time For example turn on segment a then segment b etc Review lab 7 if necessary Demonstrate to
16. pressing the ENTER key repeatedly What is the value in D1 after each instruction executes Value in D1 After Instruction Instruction Executes MOVE W D0 D1 ADDQ W 1 D1 ADD W D0 D1 ADD W 9 D1 DIVU W 2 D1 SUB W D0 D1 TRAP 14 Demonstrate the program to your lab instructor 27 28 17 18 19 Now we ll re run the program in single step mode this time using a negative value in DO Pick a negative value between 5 and 100 and convert it to 32 bit hexadecimal form What number did you choose Decimal Hexadecimal Put this value in DO and re run the program in single step mode Remember to initialize the PC to 008000 before issuing the TR command Complete the table below identifying the content of D1 and the condition code register CCR after each instruction The CCR bits are individually identified below Instruction Value in D1 X N Z V C MOVE W D0 D1 ADDO W 1 D1 ADD W D0 D1 ADD W 9 D1 DIVU W 2 D1 SUB W D0 D1 BRA Show the completed table to your lab instructor 3 3 To further explore the tracing and debugging features of MON68K a short program containing a loop is now demonstrated Place the following hexadecimal bytes in memory beginning at address 9000 29 20 2l Address Content 009000 7E 009001 04 009002 7C 009003 F4 009004 E3 0090
17. supervision of your lab instructor remove the MON68K EPROMs from the 68KMB Install the ECHO3 EPROMS in place of MON68K and test out the new but definitely not improved 68KMB Replace the MON68K EPROMsSs and verify that the 68KMB is operating properly CONCLUSION Having completed this lab students are familiar with firmware development on the 68KMB 108 MCT E E PROM PROGRAMMER v1 0 MFG Intel ZT Dig 23 Os MODEL MCT MEP C SEP 1988 TYP 2764A 27C64 PROG intelligent By Modular Circuit Technology Vpp 12 5V VCC 6 0V AIN MENU 1 DIR 2 LOAD OBJ FILE TO MEMORY BUFFER 3 SAVE EMORY BUFFER TO DISK 4 DEBUG EMORY BUFFER 5 GANG SIZE 6 PROGRAMMING ALGORITHM 7 SET MEMORY BUFFER SIZE M ANUFACTURER Ts TYPE B BLANK CHECK P PROGRA A AUTO R READ V VERIFY C COMPARE D DISPLAY amp EDIT Q QUIT SELECT WHICH NUMBER Figure 15 1 EPROM programmer menu 109 1 KKEKKKKKK KKK KKK KKK KKK KKK KKK KK KKK KK KKK KKKKKKKKKKKKKKKKKK c001 0 2 0 2 1 2 1 2 2 2 3 2 SOD SOA SBB 0 INIT 9 D7 T EX OUTSTR D7 LOOP PC a FIRMWARE SRC 768681 base address mode reg 1A mode reg 2A clock select reg A status register A command reg A Tx buffer A ASCII carriage return ASCI
18. top Modify the program to include an alarm feature Use memory locations to hold the alarm time as with the time of day When the alarm time is reached output five beeps to the console at half second intervals The time should be continually updated and displayed during the alarm Note A beep is generated by sending the ASCII bell code 07 to the console 10 2 Run the program and demonstrate it to your lab instructor CONCLUSION This lab has introduced code conversions counting and timed I O on the 68KMB using the 68681 s parallel input port parallel output port and timer I O operations were synchronized using interrupts 76 Lab 11 Interface to a Hexadecimal Keypad PURPOSE This lab introduces interfacing a keypad to a 68000 microprocessor through a 6821 peripheral interface adapter PIA Upon completion of this lab students will be able to do the following e Write program to perform input output operations using a 6821 PIA e Write programs that scan rows and columns of a keypad to determine if a key is pressed e Write programs to perform software debouncing PREPARATION Prior to the scheduled lab session read the following sections from your textbook e Section 9 11 6821 Peripheral Interface Adapter e Section 9 12 Hexadecimal Keypad Interface MATERIALS Hardware e 68KMB 68000 based computer e T O Board 5 for the 68KMB e I O Board 2 for the 63KMB e PC host computer e RS232C serial i
19. your lab instructor that you are comfortable using MON68K commands to turn the LEDs on and off 8 1 An example program called LED7 is presented in Example 9 7 in your textbook LED7 reads a 4 bit hexadecimal code from the input switches on I O Board 2 and outputs the corresponding 7 segment pattern to the display Review the software listing and the description of the program to gain an understanding of its operation Run the program and demonstrate it to your lab instructor Be prepared to answer questions on the operation of this program 8 2 Make a copy of LED7 SRC and call it LED7A SRC Put your name and the date in comment lines at the top of the source file Modify the new program such that only BCD codes are displayed If a code in the range 1010 to 1111 is read from the switches the display should appear blank Demonstrate the program to your lab instructor 8 3 An example program called LEDS5HZ is presented in Example 9 8 in your textbook LEDSHZ counts from 0 to F repeatedly at 5 Hz The count is displayed on the 7 68 segment display on I O Board 2 Review the software listing and the description of the program to gain an understanding of its operation Run the program and demonstrate it to your lab instructor Be prepared to answer questions on the operation of this program 8 4 7 Write a program to operate with the 7 segment display in I O Board 2 The program should light segments one at a time followin
20. 05 1E 009006 53 009007 47 009008 66 009009 FA 00900A 4E 00900B 4E Disassemble the program V4 4 gt DI 9000 6 The output should appear as follows SSS 009000 7E04 MOVEQ L 4 D7 Sea 009002 7CF4 MOVEQ L 12 D6 a aa 009004 E31E ROL B 1 D6 a arm 009006 5347 SUBQ W 1 D7 SSS 009008 66FA BNE S 009004 Soars 00900A 4E4E TRAP 14 Examine the program above and try to determine what it does Ask your lab instructor for assistance if necessary What is the 32 bit hexadecimal value in D7 after the first instruction executes What is the 32 bit hexadecimal value in D6 after the second instruction executes Execute the program in single step mode and complete the table below Enter as many rows as necessary to illustrate the complete execution of the program The first row is filled in to help you get started It indicates the 68000 state immediately after the first instruction executes The content of D6 is indicated as 9 since it is not initialized until the second instruction 30 PC 9002 Instruction Jus MOV t Finished EQ L 4 D7 D6 D7 00000004 31 In the table above circle the state of the Z bit in the CCR immediately after each execution of the instruction SUBQ 1 D7 Why is the state of the Z bit important immediately after the SUBQ 1 D7 instruc
21. 0C 00 00800D 02 00800E 92 00800F 40 008010 4E 008011 4E These bytes correspond to a very simple 68000 program that performs a few arithmetic operations MON68K s disassemble command DI will display the assembly language form of the program Issue the following command V4 4 gt DI 8000 7 This command disassembles seven instructions beginning at address 008000 The output should appear as follows FESS 008000 3200 MOVE W D0 D1 Baca 008002 5241 ADDQ W 1 D1 SS 008004 D240 ADD W DO D1 SSS 008006 D27C0009 ADD W 9 D1 laa aa 00800A 82FC0002 DIVU W 2 D1 HERES 00800E 9240 SUB W D0 D1 RAN 008010 4E4E TRAP 14 Each line of output from the DI command corresponds to one 68000 instruction In the example above the first instruction is in memory location 008000 The binary representation of the instruction is shown in hexadecimal as two bytes 32 followed by 00 The assembly language version of the instruction is shown on the right as MOVE W D0 D1 This instruction copies the 16 bits in the low order word of data register DO to data register D1 Since the instruction is two bytes the address of the next instruction is 008000 2 008002 25 10 11 12 13 14 The program is repeated below with a brief comment beside each instruction Examine the comments to gain an understanding of the operations The comments assume an initial value n is in data register DO when the program begins
22. 23 00009008 END EXAMPLE 41 PROCEDURE Part I Debugging 1 Work through the solution to the example problem by hand and complete the table below If you are not sure of the precise operation of any instruction consult Appendix B of your textbook As consistent with MON68K s trace facility the first column shows the PC value after each instruction executes Instruction CCR PC Just Finished X N 24 VvVic AO DO D1 MOVEA L 8006 NUMBERS AO 42 2 Enter the example problem in a file called EXAMPLE SRC Assemble the program and convert the object output file to S records Begin execution of PC VT and transfer the program to the 63KMB Use MON68K s single step facility described in lab 3 to verify your work above If you completed the table without any errors congratulations You are ready to undertake problems in assembly language programming Ask your lab instructor for assistance if you have trouble determining the correct conditions after any instruction 43 Part II Programming Problems Solve each of the following 68000 assembly language programming problems Make appropriate use of comments labels and assembler directives in your source code Enter your name the date and the problem name in comment lines at the top of each source file Prior to demonstrating your programs to your lab instructor obtain printou
23. B 31 00000024 67F6 BEQ S 32 00000026 11400006 OVE B 33 0000002A 3E1F OVE W 34 0000002C 205F OVE L 35 0000002E 4E75 RTS 36 37 KKK KKK KKK KKK KKK KKK KKK KK KKK KKK KKK KKK KKK KKK KKKKKKK KKK KKK 38 39 KKK KKK KKK KKK KKK KKK KKK KKK KKK KKK KKK KKK KKK KKKKKKKKK KKK KKK 40 00000030 2F00 OUTSTR MOVE L 41 00000032 1019 OUTSTR2 MOVE B 42 00000034 6704 BEQ S 43 00000036 61DA BSR S 44 00000038 60F8 BRA S 45 0000003A 201F EXIT MOVE L 46 0000003C 4E75 RTS 47 Figure 15 2 FIRMWARE LST page 1 of 2 110 48 KEK KKK KK KKK KKK KKK KKK KKK KKK KKK KKK KKK KKKKKKKKKKK KAKA KKK INITialize 68681 DUART channel A 49 50 INIT KEKKKKKK KKK KKK KKK KKK KKK KKK KKK KK KK KKKKKKKKKKKKK KKK KK KKK 51 DUART 52 parity 53 54 53 56 57 58 59 0000003E 207C0000 00000042 c001 00000044 117C0006 00000048 0000 0000004A 117CO00F 0000004E 0000 00000050 117CO0BB 00000054 0002 00000056 117C0005 0000005A 0004 0000005C 4E75 0000005E ODOA5465 00000062 73742066 00000066 69726D77 0000006A 61726520 OOQO0006E 70726F67 00000072 72616D00 00000076 Figure 15 2 FIRMWARE LST page 2 of 2 INIT EXT MOVEA L DUART AO MOVE B 06 MR1A A0 OVE B 0F MR2A A0 OVE B B9600 CSRA A0 OVE B 05 CRA A0 RTS DC B END FIRMWARE 111 A0 points to 7 data odd 2 stop bits Tx set baud rate Tx Rx enabled CR LF Test firmware program 0 Appendix A Che
24. DA Inc or Prentice Hall for more information Comments or suggestions are also welcome by the author Scott MacKenzie Dept of Computing and Information Science University of Guelph Guelph Ontario Canada N1G 2W1 Voice 1 519 824 4120 Ext 8268 Fax 1 519 837 0323 Email mac snowhite cis uoguelph ca This manual assumes a basic knowledge of PC computers and MS DOS The reader should be comfortable with e The most common MS DOS commands e Entering key combinations such as CTRL F4 or ALT E e Drives files directories paths e Changing the default directory or drive The 68KMB interfaces with the PC host computer through a COM port The host computer must have at least one available COM port At numerous points throughout these labs reference is made to your textbook These labs are intended to accompany The 68000 Microprocessor textbook in forming a complete course to learn about the 68000 microprocessor References to your lab instructor are made when the student must obtain expert assistance with a problem or demonstrate the solution to a problem The labs are organized using checkpoints A checkpoint is indicated by the following symbol x y The code x y indicates the sequence of checkpoints with x indicating the lab number and y indicating the checkpoint within a lab When the student reaches a checkpoint the results of the preceding steps should be demonstrated to the lab instructor Lab instructors may maintain
25. H Table 6 Each time the counter timer ready bit changes from 0 to 1 a terminal count has been reached and data can be written to the LEDs A stop command is required to clear the counter timer ready bit This is performed through the 68681 s STOP register which is address triggered see Chapter 9 Table 9 2 Any read of this register e g a TST instruction will work fine Note that when the 68681 is in timer mode as is the case here the stop command does not actually stop the timer it just clears the counter timer ready bit in the interrupt status register Put your name and the date in comment lines at the top of the source program Demonstrate the program to your lab instructor 7 6 CONCLUSION This lab has introduced simple parallel I O on the 68KMB using the 68681 s parallel input port parallel output port and timer 64 Lab 8 Interface to a 7 Segment LED PURPOSE This lab introduces interfacing to 7 segment LEDs Upon completion of this lab students will be able to do the following e Write programs that perform counting and code conversion using a 7 segment display PREPARATION Prior to the scheduled lab session read the following section from your textbook e Section 9 7 7 Segment LED Interface MATERIALS Hardware e 68KMB 68000 based computer e I O Board 2 for the 683KMB e PC host computer e RS232C serial interface cable e 20 conductor ribbon cable 65 MS DOS Software e A68K
26. I line feed 79600 baud init 68681 DUART juse D7 as counter Al gt message send it repeat until done infinite loop Al OUTCHR OUTput CHaRacter in DO to serial port QUTSTR KAKKKKKKKKK KKK KKK KK AO A7 save AO D7 A7 save D7 DUART AO AO0 points to 68681 SRA AO D7 7 get port A status 4 D7 buffer empty OUTCHR2 no check again DO TBA A0 yes send char A7 D7 restore D7 A7 A0 restore AO DO A7 EXIT OUTCHR OUTS R2 A7 D0 OUTput A1 D0 null terminated STRing save DO on stack 7 get character if null byte send it repeat restore DO done 2 3 KKK KKK KKK KKK KKK KKK KKK KKK KKK KKK KKK KKK KKK KKKKKKKKK KKK KKK 4 0000C001 DUART EQU 5 00000000 MR1A EQU 6 00000000 MR2A EQU 7 00000002 CSRA EQU 8 00000002 SRA EQU 9 00000004 CRA EQU 10 00000006 TBA EQU 11 0000000D CR EQU 12 0000000A LF EQU 13 000000BB B9600 EQU 14 15 00000000 ORG 16 00000000 613C FIRMWARE BSR S 17 00000002 3E3C0009 OVE W 18 00000006 43FA0056 LOOP LEA 19 0000000A 6124 BSR S 20 0000000C 51CFFFF8 DBRA 21 00000010 60FE BRA 22 23 KKK KKK KKK KKK KKK KKK KKK KKK KKK KKK KKK KKK KKK KKK KKKK KKK KK KKK 24 25 KKK KKK KKK KK KKK KKK KKK KKK KKK KKK KKK KKK EK 26 00000012 2F08 OUTCHR MOVE L 27 00000014 3F07 OVE W 28 00000016 207c0000 OVEA L 0000001A C001 29 0000001C 1 280002 OUTCHR2 MOVE B 30 00000020 02070004 ANDI
27. Ms are installed in the user sockets on the 68KMB they are selected at address 004000 FIRMWARE will execute at address 004000 on the 63KMB From a programming perspective position independent implies that the code segment does not include any instructions using absolute addresses For example an instruction such as JMP LOOP cannot be used because the destination of the jump is specified using absolute addressing However the instruction BRA LOOP is perfectly OK because the branch destination is specified using PC relative addressing A specific example appears in line 16 of FIRMWARE where A1 is initialized as follows LEA TEXT PC Al The source addressing mode is PC relative with offset which is position independent because the text string is the same distance from the LEA instruction regardless of the program s location Note however that the following similar instruction is not position independent and cannot be used in our example program 105 MOVEA L TEXT AL Initializing a pointer to the 68681 DUART is another story however Since the DUART resides starting at address 00C001 regardless of the address of any program that accesses it initializing an address register to point to the DUART can use a specific address This occurs in lines 28 and 51 see Figure 15 2 One final note about FIRMWARE Since this program uses the DUART to output a message to the console and since we want the program to exe
28. POSE This lab demonstrates the use of a terminal emulation program called PC VT Upon completing this lab students will be able to do the following e Define terminal emulation e Describe the difference between a DTE and a DCE e Run PC VT on a PC computer system running MS DOS e Configure the baud rate data format COM port and other modes of operation with PC VT e Issue a file transmit command with PC VT e Suspend PC VT s operation temporarily while MS DOS commands are executed e Verify that PC VT is operating properly using a wrap back test MATERIALS Hardware e PC host computer running MS DOS e RS232C interface cable provided with the 68KMB e Null modem cable optional MS DOS Software e PC VT terminal emulation program e HELP DAT help file for PC VT INTRODUCTION Terminal emulation is the act of making a computer system behave like a terminal A terminal emulator is a program that implements terminal emulation The terminal emulator provided with The 68000 Microprocessor textbook and the 68KMB 68000 based computer is called PC VT When this program is run on an IBM PC or compatible system running MS DOS the system behaves like a terminal In particular PC VT makes the system behave like a VT 100 terminal VT 100 is a model of video display terminal originally made by Digital Equipment Corporation DEC VT 100s and related models of DEC terminals are widely used as terminals on minicomputers and main
29. PU Interface b DAC output c ADC input 89 MC1 408 L8 R1 5V 1 kQ R19b PA7 150 Q PAG Riga PAS BR L 100 Q From _ Pa4 Page 1 PA3 PG PA2 ne 4 7 kQ PA1 PAO EIN TP1 3 B LM301 VO c3 L 4 15 pF a c4 m 33 pF C6 0 044 uF TP2 R20 J 2 4 kQ VOP Auxiliary Jack ra H C1 R5 RS 25 uF 1 2 KQ 1 2 KQ 8 LM30 1 Speaker C7 1 low pass volt age 0 022 uF filter 5 kQ follower T c5 am cs c 33 pF 33 pF Figure 12 1 continued 90 R7 R9 1 kQ 100 kQ VA R13 Ri 2 VB J2 Microphone 200 Q R17 1 2 KQ LF398 ADC0804 sample and hold ray V Ris m9 R16 18 KQ 5 6 kQ 1 2 kQ ESN Z Lm301 c15 L low pass filter 0 022 E R 10 kQ trimpot CB2 CB1 ne From is R4 amp 10 kQ Page 1 PBG trimpot PB5 PB4 c2 FBS 150 pF PB2 PB1 PBO Figure 12 1 continued 91 Lab 13 Interface to an Analog to Digital Converter PURPOSE In this lab an analog to digital converter ADC is interfaced to a 68000 microprocessor through a 6821 peripheral interface adapter Upon completion of this lab students will be able to do the following e Write programs to interface to an ADC through a 6821 PIA e Write programs to input speech samples through an ADC and store them in a buffer e Write a program to output the content of a buffer to an ADC PREPARATION Prior to the scheduled lab session read the following sections from your textbook e Section 9 16 Analog Input e S
30. SE This lab is an introduction to 68000 assembly language programming Students will write assemble download execute debug and demonstrate assembly language problems that solve specific yet simple programming problems Concepts from the previous labs are used extensively Upon completing this lab students will be able to do the following e Write test and debug 68000 assembly language programs to solve defined problems in data computation manipulation or conversion PREPARATION Prior to the scheduled lab session read the following chapter from your textbook e Chapter 5 Programming Examples MATERIALS Hardware e 68KMB 68000 based computer e PC host computer e RS232C serial interface cable 39 MS DOS Software e A68K 68000 cross assembler e XLINK 68000 linker locator conversion utility e PC VT VT100 terminal emulator e EDIT MS DOS text editor or equivalent 68000 Programs e EXAMPLE provided to be entered e SHIFT32 to be written e LENSTR to be written e SAME to be written e HEXCHAR to be written e LOOKUP to be written INTRODUCTION The following programming example demonstrates how problems are stated in this lab Problem Write a 68000 program called EXAMPLE to compute the sum of three 16 bit words of data The data are stored in memory starting at address 9000 identified by the label NUMBERS Store the result immediately after the data in SUM at memory location 9006 Sample Conditions
31. Table of Contents INIKODUCH ON 23 5235 iak Bis dess GA AU REA AGA GA Aaa soars ii L b 1 ntroduction to EDI 3 295 cts ene ee aa a a eu eeees 1 Lab 2 Introduction to PC VT css sssseascencoresastoadinseasesersseaniis seaenns ara REN itna eS tana aoit 9 Lab 3 Introduction to the 68K MB acces sae eas eee ea Re RS 20 Lab 4 Introduction to A68K and XLINK ccc cccececeeeeeeeeenneeeeeeeeeeeeeennneeeeeeeeeeeeeee 32 Lab 5 Programming Problems ssssnneeesssseeeeeeeeessssseseereeessssssserereeeesssssseereeeessssseseeeees 38 Lab 0 Character T O sioni ee a ua e EEE EA E ER 48 Lab 7 Interface to Switches and LEDS sssssseessseesssssssersrerssssssserereersssssserrrreess 57 Lab 8 Interface to a 7 Segment LED sssssssssssssssseessreesssssseerrreersssssserrreresssssseerreeess 64 Lab 9 Interface to a 4 Digit Display iis ccandesssdevivedeanied cddsbsvisea ina coteeeaaddes wivicsiaeeses 69 Lab 10 Interface to an 8 Digit Display ccccccccccesssssssenecceeeeeeseeseeseeaeceeeesesenees 12 Lab 11 Interface to a Hexadecimal Keypad eee eessseccccceeeeeeesesseeeceeeeeeeeeeeees 76 Lab 12 Interface to a Digital to Analog Converter eee ec eeeseeeeeeenceeeeeeneeeeeeeeaes 80 Lab 13 Interface to an Analog to Digital Converter i cc eeeseeeeesseeeeeeesneeeeeeenaes 90 Lab 14 Modular Programming ccccceeeeeesssneccceeeeeeeeeeennaeeeeeeceeeeeeeenaeeeeeeeeseeeee 95 Lab 15 Firmware
32. VT and obtain the MONO68K prompt from the 68KMB 3 An example program called TIME is presented in Example 9 10 in your textbook TIME outputs the time to the eight digit display on I O Board 4 The time is updated in one second intervals This is a relatively complex program since output to the display is synchronized by interrupts In fact MON68K operates concurrently with the interrupt routine that updates the output display Review the software listing and the description of the program to gain an understanding of its operation The program is in the directory 68KMB on the PC host computer Run the program After the program begins executing the time 1 00 00 is displayed and control is passed back to MON68K A new time is set using MON68K s memory modify command Answer the following questions What memory locations must be modified to set the time Hours Minutes Seconds Which of the 68000 s interrupt levels is used in this example How are interrupts generated in this example What are the first three instructions to execute in response to an interrupt for this example 75 What will happen if a level 1 interrupt occurs while the program is executing Why Demonstrate the program to your lab instructor Be prepared to answer questions on the operation of this program 10 1 4 Make a copy of TIME SRC and save it in a file called ALARMCLK SRC Put your name and the date in comment lines at the
33. a 68000 based single board computer containing a simple monitor program called MON68K The monitor program is stored in EPROM and supports about 17 commands Upon completion of this lab students will be able to do the following e Operate the 63KMB using its monitor program MON68K e Use MON68K commands to examine and change data values in the 68KMB s memory e Use MON68K commands to examine and change data values in the 68000 s registers e Use MON68K commands to enter and execute programs e Use MON68K commands to debug programs using breakpoints single stepping register display etc PREPARATION Prior to the scheduled lab session read the following section from your textbook e Appendix E Command Descriptions MATERIALS Hardware e 68KMB 68000 based computer e PC host computer e RS232C serial interface cable 20 MS DOS Software e PC VT terminal emulation program INTRODUCTION This lab introduces the operation of the 68KMB and its monitor program MON68K Complete details are given in your textbook Chapter 8 describes the 68KMB hardware and Appendix E describes the monitor program MONO68K In particular complete details of each of MON68K s commands are given in Appendix E It will be necessary to read portions of Appendix E while working through this lab The 68KMB is intended to work with a PC host computer running MS DOS Program development requires several steps The program is edited assembled and conve
34. a record of checkpoints to assign marks or to gauge students progress as each lab is completed Software Installation To install all the software from the 68KMB diskette onto the PC host computer proceed as follows l Place the student disk in drive A or drive B of the PC host system Ze Change the default drive to A or B as appropriate 3 Type INSTALL This will install all the software for the 68KMB on drive C in a directory called 68KMB It is suggested that you make all program files read only by issuing the following MS DOS commands User input is underlined C 68KMB gt ATTRIB R C 68KMB gt ATTRIB R PARMS DAT ATTRIB must be in a directory specified in the current path The file PARAMS DAT contains configuration information for the terminal emulation program PC VT It should remain read write for the moment in case the configuration of PC VT must change If you are re installing the software bear in mind that read only files cannot be over written Make all files read write before attempting to re install the software In a Hurry For a quick test of your 68KMB system proceed as follows after installing the software 1 With the serial cable provided connect the 683KMB to the COM port on the PC host computer preferably COM1 The cable should connect to J3 on the 63KMB 2 Plug the AC adapter into a 110 Volt AC wall outlet Attach the jack at other end of the cable to J4 on the 683KMB Run t
35. ab has introduced character I O on the 68KMB using a 68681 DUART QUESTIONS 1 If odd parity is enabled what is the state of the parity bit for the following character codes 56 At 4800 baud what is the duration of each bit transmitted How many characters per second can be continuously transmitted at 1200 baud using 7 data bits no parity 1 start bit and 1 stop bit An asynchronous serial interface is configured to operate at 4800 baud with start bit 7 data bits 1 stop bit and no parity What is the maximum number of characters that can be transmitted across this interface in one minute 57 Lab 7 Interface to Switches and LEDs PURPOSE This lab introduces parallel input output with the 63KMB Upon completion of this lab students will be able to do the following e Write programs that input data from the parallel input port on the 68681 DUART e Write programs that output data to the parallel output port on the 68681 DUART e Write programs that synchronize input output operations using software delays or a programmable timer PREPARATION Prior to the scheduled lab session read the following sections from your textbook e Section 9 4 Switches and LEDs e Section 9 5 68681 Timer MATERIALS Hardware e 68KMB 68000 based computer e I O Board 1 for the 63KMB e PC host computer e RS232C serial interface cable e 20 conductor ribbon cable 58 MS DOS Software
36. ab session read the following section from your textbook e Section 4 2 Assembler Operation 33 MATERIALS Hardware 68KMB 68000 based computer PC host computer RS232C serial interface cable MS DOS Software e A68K 68000 cross assembler e XLINK 68000 linker locator conversion utility e PC VT VT100 terminal emulator e EDIT MS DOS text editor or equivalent 68000 Programs e MYNAME provided to be entered e FUN to be written PROCEDURE 1 Using EDIT or a text editor of your own choice enter the 68000 assembly program in Figure 4 1 and save it in a disk file called MYNAME SRC Change the program so that the line containing the label MESSAGE contains your name MYNAME SRC CR EQU SOD ASCII carriage return LF EQU SOA ASCII line feed ORG 8000 MYNAME OVE W 10 D6 repeat 10x LOOP OVEA L MESSAGE A1 Al points to message TRAP 2 send message SUBO W 1 D6 decrement count BNE LOOP if not 0 do it again TRAP 14 jif 0 return to MON68K MESSAGE DC B Scott MacKenzie DC B CR LF carriage return line feed DC B 0 end with null byte END MYNAME Figure 4 1 MYNAME SRC 2 Assemble the program by entering the command C 68KMB gt A68K MYNAME SRC MYNAME LST MYNAME OBJ X S 34 The command above A68K contains five arguments In order these are e source file to assemble MYNAME SRC e name of output file for the program listing MYNAME LST e nam
37. able 7 1 there is an inverse relationship between the output register bits and the output pins The operation of the 68681 s output port may seem odd but there is a good reason for it to work as it does Consider that the outputs might be divided among two or more interfaces If the software driver for one interface needs to set or clear a few bits in the output port while leaving the others as is there is no easy way to do so since the output port is write only The 68681 implementation is a simple solution to this allowing output pins to be set or cleared independent of other pins Writing an 8 bit value to the output pins requires three steps First the value is written to OPR_CLR Second the value is complemented Third the complemented value is written to OPR_SET For example to copy the contents of the low byte in DO to the output port the following instruction sequence could be used MOVE B DO SOOCO1F write to OPR_CLR NOT B DO complement data MOVE B DO 00C01D write to OPR_SET 61 PROCEDURE 1 With the 68KMB powered off connect I O Board 1 to J1 Power on the 68KMB and the PC host computer Execute PC VT and obtain the MONO68K prompt from the 68KMB Use MON68K s memory modify command to read the state of the switches connected to the 6868 1 s parallel input port V4 4 gt MM CO1B The value displayed reflects the state of the input switches Toggle some of the input switches and re read the input port
38. ckout and Calibration Procedure for I O Board 6 Part I Setup 1 Perform the usual setup procedure for the 68KMB 2 Using a 20 conductor ribbon cable connect I O Board 6 to J2 on the 68KMB 3 Connect the 12 volt or 15 volt external power supply to the the banana jacks on T O Board 6 4 Power up the 68KMB then power up the external power supply 5 Run PC VT and obtain the MON68K prompt on the console Part II DAC 1 A test program called SAWTOOTH is found in the C 68KMB directory on the PC host computer Load and run SAWTOOTH and measure the waveform at TP1 using an oscilloscope Adjust R1 to obtain a 0 10 volt waveform 2 Adjust R2 to verify that an audible tone is heard through the on board speaker Part III ADC 3 Press and release the RESET switch on 68KMB Measure the clock waveform at pin 4 of the ADC0804 IC3 Adjust R4 to obtain f 640 kHz p 1 56 us Notes i The clock waveform will be triangular and will range from about 0 5 volts to 2 volts ii The clock many be up to 1 46 MHz p 0 68 us but not lower than 640 kHz ii If the clock cannot be adjusted within 640 kHz to 1 46 MHz remove capacitor C2 on I O Board 6 and replace as follows a Iff lt 640 kHz p gt 1 56 ms replace C2 with a 100 pF capacitor b Iff gt 1 46 MHz p lt 0 68 ms replace C2 with a 220 pF capacitor 113 I O Board 6 is delivered with a jumper in X1 Move this jumper to X2 Load and run the test pro
39. conductor ribbon cable 73 MS DOS Software e A68K 68000 cross assembler e XLINK 68000 linker locator conversion utility e PC VT VT100 terminal emulator e EDIT MS DOS text editor or equivalent 68000 Programs e TIME provided in 68KMB directory e ALARMCLK to be written INTRODUCTION This is the fourth in a series of labs to explore interfacing with the 68KMB I O Board 4 is an interface between the 68681 on the 68KMB and a 8 digit output display The output consists of eight 7 segment LED displays driven by two MC14499s Only three 68681 output signals are required even though the display contains eight digits This is possible because the MC14499s can be cascaded as illustrated in Figure 10 1 DIGIT DIGIT J1 20 pin Header MC14 499 MC14499 OP2 DATA DATA nc Tout Sr oat a on the nc 68KMB ne see I O BOARD 3 for pinouts etc Figure 10 1 I O Board 4 The interface is described in detail in The 68000 Microprocessor Section 9 9 Review this before proceeding 74 This is our first lab that uses interrupts Interrupts represent a significant leap forward one which poses special challenges for students The sections listed as Preparation should be studied carefully before proceeding Ask your lab instructor for assistance if any of the concepts on interrupts are unclear PROCEDURE 1 With the 68KMB powered off connect I O Board 4 to J1 2 Power on the 68KMB and the PC host computer Execute PC
40. ctor at the end of the RS232C cable is a 25 pin DB25P The suffix P stands for pin The mate for this connector is a DB25S socket connector The pin sequence is shown in Figure 2 1 as viewed from the end of the DB25P connector Of the 25 pins only three are needed for the interface between the PC host computer and the target computer The purpose of each is given in Table 2 1 Table 2 1 Signals for Serial Connection From a PC to a Target Computer Pin Signal Number Mnemonic Name Purpose 2 TxD Transmit Data Data from PC host computer to the target computer 3 RxD Receive Data Data into PC host computer from the target computer 7 GND Signal Ground Common ground between systems at each end of cable A serial device that operates with the signal directions in Table 2 1 is called a DTE for Data Terminal Equipment If the signals travel straight through the cable from one device to the other then pin 2 which is an output from the PC host computer in Figure 2 1 must be an input for the device at the other end of the cable Similarly pin 3 which is an input for the DTE is an output from the device at the other end of the cable A device which communicates with a DTE using a straight through cable is called a DCE for Data Communications Equipment Historically DTEs are devices at the terminus of a connection such as computers and terminals whereas DCEs are modems This distinction is often blurred on many of
41. cute immediately after a system reset we must include the appropriate code to initialize the DUART We have not had to do this previously because our programs were executed from MON68K The DUART was already initialized So FIRMWARE includes an INIT subroutine lines 51 56 and BSR INIT at the beginning line 16 For the second program we ll use ECHO2 from lab 14 Begin by copying ECHO2 SRC MYLIB2 SRC and ECHO2 XLK to new files ECHO3 SRC MYLIB3 SRC and ECHO3 XLK The program will have to be modified replacing absolute memory references within the code segment with relative addressing Since ECHO2 is your program we ll leave it to you to sift through the code and introduce the appropriate modifications Change the prompt too Sharon s FIRMWARE echo program Enter a command Since we want this program to be stand alone it must include an INIT subroutine as in the FIRMWARE example program Delete the code supporting the g command as well Remember to modify ECHO3 XLK changing the filenames as appropriate Leave the data segment at address 00A000 since this is the location of the 63KMB s RAM It s a good idea to debug the modified program in RAM with the code segment at address 008000 as in lab 14 When a position independent version of ECHO3 is working at address 008000 modify ECHO3 XLK and change address of the EPROM segment to 0 Re link burn the new program into EPROM install it in the user sockets and try it out
42. d the other socket is for the lower byte data odd addresses By default the 683KMB configures these sockets for 2764 or 2764A EPROMs beginning at address 004000 A 2764 contains 8K by 8 bits so the two user sockets can hold a program up to 16K bytes in length An additional feature of the 683KMB allows the program in the user EPROMs to execute immediately after a system reset This will occur if jumper X16 is installed MON68K senses whether or not X16 is installed upon reset If X16 is not installed MON68K proceeds as usual If X16 is installed execution is transferred to address 004000 The importance of this feature is that a terminal or host computer is not needed to initiate the user program If X16 is installed execution following a reset operation immediately passes to the user EPROMs This lab assumes an EPROM programmer is available and that the lab instructor will demonstrate its operation to students At the University of Guelph we use an inexpensive EPROM programmer from Modular Circuit Technology MCT Figure 15 1 near the end of this lab illustrates the menu that appears when the accompanying programming software EPP 01 is executed A sub menu appears for each command making the operation of the EPROM programmer very simple With the MCT programmer a hex file S records must be converted to a binary file before programming A utility called HEXOBJ performs this conversion One point about programming EPROMs deserves
43. e 10K trimpot labeled R3 in Figure 12 1c If X3 is installed input is from an external transducer connected to J5 on I O Board 6 Install a jumper in X2 Remove the jumper from X1 if it is present An example program called ADCTEST is presented in Example 9 16 in your textbook The program continually reads the ADC0804 and reports the result of the conversion on the console Review the software listing and the description of the program to gain an understanding of its operation The program is in the directory 68KMB on the PC host computer Run the program and connect an oscilloscope or voltmeter to test point 6 TP6 Demonstrate the program to your lab instructor Adjust the trimpot R3 to the following voltages as measured at TP6 For each voltage what is the converted result read from the ADC0804 0 volts 1 volt 2 volts 3 volts 4 volts 5 volts 94 13 2 Power off the 683KMB by removing the AC adapter jack and by switching off the external power supply connected to I O Board 6 For the next part of this lab we will add I O Board 3 the 4 digit LED display Connect I O Board 3 to J1 on the 63KMB Power on the 68KMB and switch on the external power supply connected to I O Board 6 Execute PC VT and obtain the MON68K prompt Make a copy of ADCTEST SRC and call it ADCTEST2 SRC Put your name and the date in comment lines at the top Modify the new program such that the output is sent to
44. e 6821 PIA and the keypad interface are discussed in Section 9 11 and Section 9 12 of your textbook Review this material before proceeding PROCEDURE 1 With the 68KMB powered off connect I O Board 5 to J2 79 2 Power on the 68KMB and the PC host computer Execute PC VT and obtain the MONO68K prompt from the 68KMB 3 An example program called KEYPAD is presented in Example 9 12 in your textbook KEYPAD scans the rows and columns of the keypad to determine if a key is pressed The program includes software debouncing to ensure the mechanical contacts in the keypad have stabilized When a clean key closure is detected the ASCII code for the key is sent to the console Review the software listing and the description of the program to gain an understanding of its operation The program is in the directory 63KMB on the PC host computer Run the program and demonstrate it to your lab instructor Be prepared to answer questions on the operation of this program 11 1 4 Power off the 683KMB For the next part of this lab we will use two I O Boards T O Board 5 and I O Board 2 Connect I O Board 2 to Jl on the 68KMB Power on the 68KMB Execute PC VT and obtain the MON68K prompt from the 68KMB 5 Make a copy of KEYPAD SRC and save it in a file called KEYPAD2 SRC Put your name and the date in comment lines at the top Modify the program such that the output is sent to the 7 segment display on I O Board 2 rather than to the cons
45. e A68K e XLINK e PC VT e EDIT 68000 Programs e WIRE681 e ROTATE e TWOHZ e KEYTEST e FIVEHZ INTRODUCTION 68000 cross assembler 68000 linker locator conversion utility VT100 terminal emulator MS DOS text editor or equivalent provided in 68KMB directory provided in 68KMB directory provided in 68KMB directory to be written to be written This is the first in a series of labs to explore interfacing with the 683KMB These labs use I O boards that connect either to J1 or J2 on the 68KMB This lab uses I O Board 1 which interfaces to the 63KMB through J1 This is illustrated in Figure 7 1 I O Board AC adapter 110 VAC From PC Host computer 68KMB 68000 CPU J3 20 conductor ribbon cable Figure 7 1 Connecting an I O board to J1 on the 63KMB J1 provides access to the 68681 s parallel input port and parallel output port as shown in Figure 8 15 in The 68000 Microprocessor 59 I O Board 1 contains a very simple interface to LEDs and switches see Figure 7 2 The output port signals on the 68681 are labeled OPO to OP7 Each signal interfaces to an LED through a buffer and a resistor Writing a zero to a port pin turns the corresponding LED on Writing a one to a port pin turns the corresponding LED off Upon reset all port pins are one therefore all LEDs are off J1 20 pin Header 74LS244 To J1 onthe 6 8 KMB Figure 7 2 I O Board 1 The 68681 s parallel input por
46. e of output file for the binary object code MYNAME OBJ e option to create a cross reference listing X e option to place a symbol table in the object file S The program listing file is a text file which may be printed or displayed on the system screen The object file contains binary codes and cannot be printed Have a look at the program listing by entering the command C 68KMB gt TYPE MYNAME LST T This command displays the contents of the specified file on the CRT display Press the PAUSE key if the output scrolls too fast Press the SPACE bar to resume output Examine the listing file and try to identify opcodes for the instructions in the program Figure 4 2 shows the contents of MYNAME LST Your listing file will be very similar differing only in the ASCII bytes for your name ADO BWNE Nr OW Oo 0000000D 0000000A 00008000 00008000 00008004 00008008 0000800A 0000800C 0000800E 00008010 00008012 00008016 OO00801A 0000801E 00008021 00008023 00008024 3C3C000A 227C0000 8012 4E42 5346 66F4 4E4E 53636F74 74204D61 634B656E 7A6965 ODOA 00 MYNAME SRC CR EQU LF EQU ORG MYNAME MOVE W LOOP MOVEA L TRAP SUBQ W BNE TRAP MESSAGE DC B DC B DC B END SOD ASCII carriage return SOA ASCII line feed 8000 10 D6 repeat 10x MESSAGE Al Al points to message 2 send message 1 D6 decrement count LOOP if not 0 do it again 14 if 0 return to MON68K Scott MacK
47. e of the directories listed will be CADOS QBASIC EXE are stored This is where the files EDIT COM and Verify the presence of these files by entering the following command C gt DIR DOS P Both EDIT COM and QBASIC EXE should appear in the long list of files that appears on the console EDIT COM and QBASIC EXE must be present in the directory DOS or in a directory listed in the search path instructor for assistance If you cannot find these files ask your lab For this lab we will create a new directory for our example file Create a directory called LAB1 by entering the command C gt MKDIR LAB1 Make the new directory the default directory by entering the command C gt CD LAB1 The prompt should change to C LAB1 gt PART II Using EDIT COM 5 EDIT A FILE Now we will use EDIT to create and edit an example file Enter the command C LAB1 gt EDIT EXAMPLE TXT This command starts EDIT and brings the user into a full screen editor The text entered will be saved in a file called EXAMPLE TXT 6 TEXT ENTRY Begin by typing the following three lines exactly as shown Each line is terminated by pressing the ENTER key This is a test of DOS EDIT This is the second line of th xample fil This is the last line of th xample fil 7 CURSOR MOVEMENT With these three lines entered we can illustrate the most common editing features of EDIT The primary cursor movement
48. ection 9 17 Digitized Speech Input and Playback 92 MATERIALS Hardware 68KMB 68000 based computer MS DOS Software 68000 Programs INTRODUCTION T O Board 6 T O Board 3 microphone 200 Q power supply 12 volt or 15 volt screwdriver PC host computer RS232C serial interface cable two 20 conductor ribbon cable PC VT ADCTEST ADCTEST2 SPEECH SPEECH2 VT100 terminal emulator provided in the 68KMB directory to be written provided in the 68KMB directory to be written This lab is a continuation of lab 12 Our main focus is on the analog input channel on I O Board 6 An ADC0804 8 bit analog to digital converter connects to Port B of the 6821 PIA as shown in Figure 12 1 in lab 12 The interface also includes three op amps and a sample and hold circuit to allow input from a microphone The ADC interface is discussed in Sections 9 16 and 9 17 of your textbook Review these before proceeding PROCEDURE l 2 With the 68KMB powered off connect I O Board 6 to J2 With the external power supply switched off connect the power supply cable to I O Board 6 93 Have your lab instructor verify the connections before turning the power on 13 1 Notice in Figure 12 1c lab 12 that jumpers X1 X2 and X3 select between three possible inputs to the ADC If X1 is installed the ADC s input is from the microphone and the conditioning circuitry If X2 is installed the ADC s input is from th
49. enzie CR LF begin a new line 0 end with null byte MYNAME Figure 4 2 MYNAME LST 35 What are the machine language bytes for the instruction MOVEA L MESSAGE A1 What are the first five ASCII bytes for your name as found in your version of this program 4 1 It was stated above that the object file contains binary codes and therefore cannot be printed Convince yourself of this by entering the command C 68KMB gt TYPE MYNAME OBJ The output to the CRT is garbled In the worst case some of the binary codes may lock up your system Enter CTRL ALT DEL to re boot your system if necessary Convert the object file to hex ASCII format by entering the command C 68KMB gt XLINK 68K MYNAME OBJ O MYNAME HEX The command above XLINK contains three arguments e the CPU type 68K e the object file to convert MYNAME OBJ e the name of the file to receive the output O MYNAME HEX As well as linking program modules together described in a later lab the XLINK program converts object files to hex ASCII format The latter contain Motorola S records which conform to a standard format to represent binary programs in ASCII Each binary byte is stored by splitting it into two 4 bit hexadecimal nibbles Each nibble is coded as the corresponding ASCII character 0 9 A F Motorola S records are explained in detail in Chapter 1 of your textbook Figure 4 3 illustrates the S records for the prog
50. frame computers such as the VAX by DEC If a PC is running a VT 100 terminal emulation program such as PC VT then the PC can act as a terminal and communicate with a VAX or other computer as though it were a VT 100 terminal PC VT will be used throughout this and subsequent labs to conveniently turn the PC host computer into a VT 100 terminal for connection to a target computer The purpose of this lab is to introduce the operation of PC VT and some concepts in connecting terminals to computers through serial RS232C interfaces In subsequent labs we will use a PC host computer running PC VT to act as a terminal for connection to the 68KMB 68000 based computer For this lab we need a PC host computer an RS232C serial interface cable and of course PC VT Figure 2 1 illustrates the PC host computer and the RS232C serial interface cable PC DB25P Connector RS23 2C serial interface cable Connection to back of PC End view Figure 2 1 PC host computer with RS232C serial interface cable 10 For a brief introduction to asynchronous serial communications using RS232C see Chapter 9 of your textbook PC VT communicates through a serial port on the PC host computer Although PCs may have four or more serial ports usually only one or two are present These are referred to as COMI and COM2 The RS232C serial interface cable connects to one of the COM port connectors on the back of the PC host computer The conne
51. g a pattern around the outside of the display a b c f a b and so on The frequency of rotation should be 5 Hz That is segment a is on for 200 ms segment b is on for 200 ms and so on Bonus Place the output instructions in an interrupt service routine and time the rotation using the 68681 timer Example 9 6 in your textbook illustrates how to create timed interrupts using the 68681 timer Review this if necessary Call the new program RSEGMENT Put your name and the date in comment lines at the top Demonstrate the program to your lab instructor 8 5 CONCLUSION This lab has introduced code conversions counting and timed I O on the 68KMB using the 68681 s parallel input port parallel output port and timer 69 Lab 9 Interface to a 4 Digit Display PURPOSE This lab introduces interfacing to a 4 digit display Upon completion of this lab students will be able to do the following e Write programs that perform counting and code conversion using a 4 digit display e Write programs that perform parallel to serial data conversion using a parallel output port and an MC14499 serial display driver e Write programs to output a 4 digit count in decimal at a fixed rate PREPARATION Prior to the scheduled lab session read the following section from your textbook e Section 9 8 4 Digit 7 Segment Display MATERIALS Hardware e 68KMB 68000 based computer e I O Board 3 for the 683KMB e PC host computer e
52. gram ADCTEST Observe the output on the console while adjusting R3 The output should vary from 00 to FF Move the jumper to the X1 position Install the microphone provided with I O board 6 in J2 and load the SPEECH program The switch on side of microphone should be on Run the record routine by entering GO 8000 from the MON68K prompt After pressing the RETURN key speak into the microphone for about 1 5 seconds until the MON68K prompt re appears Run the playback routine by entering GO 800C from the MON68K prompt Adjust R2 to control the volume of output The quality of audio output is improved by installing an amplified external speaker system to auxiliary jack J1 114
53. he terminal emulation program Note user input is underlined C 68KMB gt PC VT Press and release the RESET switch on the 68KMB The 68KMB s monitor program MON68K will output the following prompt MON68K V4 4 gt Note If this prompt does not appear verify that the 68KMB is connected to COMI on the PC host computer To re configure PC VT to communicate through COM2 follow steps 8 15 in Lab 2 If you still have problems perform a thorough check of the RS232C serial interface by following lab 2 from the beginning Issue MON68K s load command V4 4 gt LO Issue a File Transmit command to PC VT CTRL F4 PC VT s File Transmit dialog box will appear Enter DEMO HEX The demonstration program is transferred from the PC host computer to the 68KMB s memory Enter Y when asked if CTRL Z should be transmitted Execute the demo program V4 4 gt GO 8000 A welcome message is displayed on the CRT display of the PC host computer 10 Terminate PC VT CTRL F8 Quick Test of A68K and XLINK As a quick demo of the 68KMB programming environment we will use EDIT the editor supplied with MS DOS 5 0 or later to modify the demo program The modified program will be assembled linked and downloaded to the 68K MB for execution Use an editor of your own choice if you prefer 1 From the MS DOS prompt enter C 68KMB gt COPY DEMO SRC DEMO2 SRC C 68KMB gt EDIT DEMO2 SRC Make s
54. host computer Congratulations you are now ready to have fun with the 683KMB vii Lab 1 Introduction to EDIT PURPOSE This lab demonstrates the use of MS DOS s full screen editor called EDIT Upon completion of this lab students will be able to do the following e Create and edit text files using EDIT e Perform a variety of editing operations on a text file such as deleting copying or moving selected regions of text MATERIALS Hardware e PC host computer running MS DOS 5 0 or later MS DOS Software e EDIT MS DOS editor e QBASIC used by EDIT Note The program QBASIC EXE is used by EDIT COM QBASIC EXE must be in the same directory as EDIT COM or in a directory in the search path INTRODUCTION Beginning with version 5 0 MS DOS includes a simple full screen editor called EDIT EDIT allows the user to create and edit unformatted text files such the MS DOS batch files AUTOEXEC BAT or CONFIG SYS These files contain unformatted ASCII text The 68000 assembly language source programs written in subsequent labs are also stored in unformated text files These files are considered unformatted because they only contain ASCII graphic characters letters numbers and punctuation and control characters such as CR carriage return LF line feed or HT horizontal tab Files created with a word processor are more complex They contain a variety of binary formatting codes defining the page layout fonts etc Although m
55. iable CODE at location 9001 If DIGIT does not contain a single BCD digit clear CODE Assume a standard segment arrangement e g 74LS47 with segment a as bit 0 and segment g as bit 6 bit 7 0 always This is shown below Assume a segment is ON for a 1 and OFF for a 0 Hint begin by constructing a table of BCD to CODE mappings f b g Eed e c d C Sample Conditions Before Address Contents 009000 0400 After 009000 0466 Note Verify that your program works for any value from 0 to F 5 6 CONCLUSION Having completed this lab students are capable of writing small 68000 programs in assembly language 48 Lab 6 Character I O PURPOSE This lab introduces the low level details of character input output on the 68KMB Upon completion of this lab students will be able to do the following e Write subroutines to perform character input output on an asynchronous serial interface e Use character I O subroutines in programs that receive input from a keyboard and send output to a CRT display PREPARATION Prior to the scheduled lab session read the following sections from Chapter 9 Interface Examples of your textbook e Section 9 1 Introduction e Section 9 2 The 68681 DUART e Section 9 3 RS232C Interface MATERIALS Hardware e 68KMB 68000 based computer e PC host computer e RS232C serial interface cable 49 MS DOS Software e A68K EXE 68000 cross assembler e XLINK EXE 68000 linker loca
56. interface between the MON68K and a terminal or host computer uses a serial RS232C communications channel Each character is transmitted in the following sequence 50 e a start bit low e 7 or 8 data bits LSB first e a parity bit optional e astop bit high This type of communications is called asynchronous since the receiver must re synchronize itself with each new character Usually 7 data bits are used since this is the size of ASCII codes Figure 6 1 shows the ASCII code for the letter a framed by a start bit an odd parity bit and a stop bit Odd parity means the total number of bits equal to one is an odd number Only the data bits and the parity bit are counted The reciprocal of the transmission time for each bit is called the baud rate For the 68KMB the baud rate is 9600 so the period of transmission for each bit is 104 us Stop Idle y Bit State St an 7 Data Bits ree Idle Bit LSB First State Ca 61 o ey 0 Ta oe Baud Rate time Figure 6 1 Asynchronous character transmission Of course characters are stored in parallel in registers or memory locations so transmission on an RS232C interface requires special devices at each end to perform parallel to serial conversion or vice versa On the 68KMB this device is a 68681 DUART Dual Universal Asynchronous Receiver Transmitter Although the 68681 includes two separate serial interface channels we will only use Channel A in th
57. irst and last address of the RAM buffer used in the program What is the address of the OUTSTR subroutine Execute PC VT and transfer ECHO HEX to the 68KMB Verify that the program is in the 68KMB s memory What MON68K command did you enter Run the program and demonstrate it to your lab instructor 14 2 Now we ll modify ECHO First make copies of ECHO SRC MYLIB SRC ECHO XLK and save them in ECHO2 SRC MYLIB2 SRC and ECHO2 XLK respectively Put your name and the date in comments lines at the top of each source file Change the prompt to Sharon s program Enter a command Use your name please Modify the program to interpret the first character on each line as follows Q Quit to MON68K this is already supported U Echo the entire line in uppercase characters Convert lowercase characters to uppercase characters Leave graphic characters as is L Echo the entire line in lowercase characters Convert uppercase characters to lowercase characters Leave punctuation characters as is F Echo the input line forwards B Echo the input line backwards 101 Display a description of the commands supported For any other command character do not echo the line Re issue the prompt and repeat Recognize commands in both uppercase and lowercase Continue to use a modular approach in the modified program Put the code to determine the command in ECHO2 Put the code to execute commands in subroutines in MYLIB2 Reme
58. is lab Our discussion of the 68681 s features is very limited in this lab Complete details are found in The 68000 Microprocessor The hardware interface to the 68000 is presented in Chapter 8 programming examples are found in Chapter 9 and the 68681 data sheet is found in Appendix H A simplified version of the CPU interface is shown in Figure 6 2 51 System Buses Decoding 68681 1 Character 3 Character Tx Buffer Rx Buff er Baud Rate Clock Shift Register Shift Register LTE TET eT LT ET ETE I Receiver RS232 Interface to terminal host com puter Figure 6 2 Interface to the 68681 DUART The 68681 includes a double buffered transmitter and a quadruple buffered receiver During transmission one character can be waiting in the Transmit Buffer while the previous character is being transmitted out the shift register see Figure 6 2 For character reception a three character FIFO first in first out buffer holds characters waiting to be read through software while the next character is clocked into the shift register In Figure 6 2 note the special interface ICs between the 68681 and the RS232C interface An RS232C line driver converts the voltage of outgoing signals from TTL transistor transistor logic levels to RS232C levels An RS232C line receiver converts the voltage of incoming signals from RS232C levels to TTL levels This conversion is summarized in Table 6 1 Table 6 1 TTL RS232C Signal Con
59. keystrokes are listed below Keystrokes Movement Arrow Keys One character or one line CTRL LEFT ARROW One word to the left CTRL RIGHT ARROW One word to the right HOME Beginning of the line END End of the line CTRL ENTER Beginning of the next line CTRL Q E Top of the window CTRL Q X Bottom of the window Experiment with the keystrokes listed above and verify the movement effect stated Although our example text is very short the following cursor movement keystrokes may be needed later when working with larger files Keystrokes Movement CTRL UP ARROW Scrolls up one line CTRL DOWN ARROW Scrolls down one line PgUp Scrolls up one screen PgDn Scrolls down one screen CTRL HOME Moves the cursor to the start of a file CTRL END Moves the cursor to the end of a file CTRL PgUp Scrolls right one screen CTRL PgDn Scrolls left one screen 8 SELECTING TEXT Most editing tasks begin by selecting text Any amount of text may be selected from a single character to the entire file Experiment with the following steps on the example text To Select a Block of Text Position the cursor at the first character you want to select Hold the SHIFT key and move the cursor to the last character you want to select The text selected is highlighted as the cursor moves Release the keys The text is selected To de select the text press any cursor movement ke
60. le The example file should look like this 11 12 13 This This This This is a test of DOS EDIT is the second line of th xample fil is a test of DOS EDIT is the last line of th xample fil REPLACING TEXT Use the steps below to change all instances of DOS to MS DOS The example file should look like this This This This This is a test of MS DOS EDIT is the second line of th xample fil is a test of MS DOS EDIT is the last line of th xample fil To Replace Existing Text With New Text Position the cursor where you want to begin replacing text Press ALT S to activate the SEARCH menu Press C to activate the CHANGE dialog box Enter the text you wish to change in the Find What box Press TAB to advance the cursor to the Change To box Enter the new text you want the original text to be replaced with Press ENTER to begin changing Follow the instructions as you proceed Press C to accept changes press S to skip changes press ESC to terminate SAVING A FILE Use the steps below to save the example text to a disk file Leave the name of the file as EXAMPLE TXT To Save an Edited File Press ALT F to activate the FILE menu Press S to save the file with its current name OR Press A to save the file with a new name Type the new name and press ENTER EXIT Use the steps below to exit EDIT and re
61. le STEP to 0020 Re run the program What is the frequency of the sine wave Change the variable STEP to 0080 and re run the program What is the frequency of the sine wave 12 5 The DAC circuit includes additional output stages to create audio tones for music or speech output Section 9 15 in your textbook describes the circuit and presents a technique to create musical tones Review this section before proceeding A program called AMAJOR is presented in Example 9 15 in your textbook The program uses the console keyboard to create musical tones on the loudspeaker on VO Board 6 The volume is controlled by potentiometer R2 If an amplified external speaker is available connect it to J1 on I O Board 6 Review the software listing and the description of the program to gain an understanding of its operation The program is in the directory 68KMB on the PC host computer Connect channel A of the oscilloscope to TP1 and channel B to TP2 Run the program and demonstrate your musical skill to your lab instructor 12 6 87 CONCLUSION This lab has introduced interfacing to a digital to analog converter using a 6821 PIA and an MC1408L8 8 bit DAC 88 39 40 wo wo wo wo N N N N wo N k e o N JS 5 See i Page 2 5 4 23 __ 3 To J2 on the 68KMB a 16 15 RESET 14 13 12 See NTS 11 Page 3 10 19 18 J4 D3 1N4001 Auxiliary da Power GND Supply 12V 1N4001 a Figure 12 1 I O Board 6 a C
62. mber to change the filenames in ECHO2 XLK as appropriate Demonstrate the new program to your lab instructor 14 3 x Having completed this lab students are familiar with modular programming in 68000 assembly language CONCLUSION 102 Lab 15 Firmware Development PURPOSE This lab introduces firmware development the process of putting a program into EPROM for execution on a target system Upon completion of this lab students will be able to do the following e Write 68000 programs which are position independent e Burn a 68000 program into EPROM e Install EPROMs on a target system e Execute a user program installed in EPROM on a target system MATERIALS Hardware e 68KMB 68000 based computer e PC host computer e EPROM programmer e RS232C serial interface cable MS DOS Software e A68K 68000 cross assembler e XLINK 68000 linker locator e EPP 01 EPROM programming software or equivalent e HEXOBJ hex to binary conversion utility or equivalent e EDIT MS DOS editor or equivalent e PC VT VT100 terminal emulator 103 68000 Programs e FIRMWARE in 68KMB directory e ECHO3 to be written e MYLIB3 to be written INTRODUCTION Software burned into EPROM is called firmware The process of writing software which will eventually execute in EPROM is called firmware development The 68KMB includes two EPROM sockets for user programs One socket is for the upper byte data even addresses an
63. n be transmitted from one system to the CRT display on the other system 2 2 18 24 Terminate PC VT by pressing CTRL F8 CONCLUSION This lab has introduced PC VT the terminal emulation program that will be used throughout the rest of the labs Table 2 2 summarizes the PC VT commands demonstrated in this lab Table 2 2 PC VT Commands PC VT Command Effect ALT F Suspend PC VT and go to MS DOS ALT H Access on line help CTRL F1 Go to SETUP A screen CTRL F4 File Transmit CTRL F8 Terminate PC VT ADDENDUM A variety of other modes are selected by toggling bits displayed along the bottom line of the SETUP B display These bits are accessed by moving the cursor with the left arrow and right arrow keys As the cursor passes over each mode bit a brief message summarizes the effect of the bit A mode bit may be toggled by pressing 6 as noted on the SETUP B display It should not be necessary to change any of the these bits but knowing what each does may be helpful for debugging terminal related problems later Note Changes introduced through PC VT s SETUP A or SETUP B screens take effect immediately and stay in effect until PC VT is terminated If changes are not saved using the S option in the SETUP A screen then the next time PC VT is run the previous settings are restored 19 Lab 3 Introduction to the 68KMB PURPOSE This lab introduces the 68000 Mini Board the 68KMB The 68KMB is
64. n the PC host computer Run the program and demonstrate it to your lab instructor Be prepared to answer questions on the operation of this program 9 1 4 Make a copy of COUNT4 SRC and save it in a file called COUNT4D SRC Put your name and the date in comment lines at the top Modify the program to count down instead of up Demonstrate the program to your lab instructor CONCLUSION This lab has introduced code conversions counting and timed I O on the 68KMB using the 68681 s parallel input port parallel output port and timer 72 Lab 10 Interface to an 8 Digit Display PURPOSE This lab introduces interfacing to an 8 digit display Upon completion of this lab students will be able to do the following e Write interrupt driven programs for the 68000 microprocessor e Write programs that perform counting and code conversion using an 8 digit display e Write a program to output an 8 digit count at a fixed rate e Write a program to implement a time of day alarm clock e Write programs to synchronize I O operations using the 68681 programmable timer PREPARATION Prior to the scheduled lab session read the following sections from your textbook e Section 7 7 Interrupt Initiated I O e Section 9 6 68681 Timer With Interrupts e Section 9 9 8 Digit 7 Segment Display MATERIALS Hardware e 68KMB 68000 based computer e I O Board 4 for the 63KMB e PC host computer e RS232C serial interface cable e 20
65. n the auxiliary connector J1 to improve the quality of audio output 3 If the speech output is very noisy follow the calibrate checkout procedure for I O Board 6 given in Appendix A of this lab manual Make a copy of SPEECH SRC and save it in a file called SPEECH2 SRC Place your name and the date in comment lines at the top Modify the new program as follows Place the playback routine in a loop such that the content of the RAM buffer is continually sent to the DAC During playback monitor the console for keyboard input and respond in the following way when a key is pressed u the frequency of playback increases UP d the frequency of playback decreases DOWN SPACE the frequency of playback is restored to normal q quit to MON68K Ignore any other keystrokes Hint The frequency of playback can be controlled by altering the timer count Demonstrate the modified program to your lab instructor 13 5 96 CONCLUSIONS This lab has demonstrated an interface between an analog to digital converter and the 68000 microprocessor through a 6821 PIA 97 Lab 14 Modular Programming PURPOSE This lab introduces a variety of concepts relevant to developing large assembly language programs Upon completion of this lab students will be able to do the following e Define and give examples of the following terms modular programming relocatable module absolute module code segment data segment external symbol public
66. ng the command C gt CD 68KMB If this directory is not present the software from the 68KMB diskette must be installed Follow the installation procedure at the beginning of this lab manual 3 Begin execution of PC VT by entering C 68KMB gt PC VT 4 Press and release the RESET button on the 68KMB to obtain the following prompt MON68K V4 4 gt If this prompt does not appear verify that the RS232C serial cable is connected to the correct COM port Verify PC VT s baud rate data format COM port etc using the steps outlined in Lab 2 The 68KMB RS232C serial interface operates 22 at 9600 baud with 7 data bits and odd parity Ask your lab instructor for assistance if you still do not get the prompt above HELP COMMAND To obtain a brief listing of all MON68K s commands enter the help command as follows V4 4 gt HI GI The output should appear as follows xx x MON68K COMMAND SUMMARY DI disassemble instructions go to user program go to temporary breakpoint help display this message load S records and go load S records memory copy memory dump memory fill memory modify memory test register dump size of data for MD command trace delay trace instructions X set register R to value X display this message CQQ HO DDAONUH SE FHVAQ00O E ZE HuNDAE SES H 1 A detailed description of each command is given in Appendix E of your tex
67. nterface cable e 20 conductor ribbon cable 77 MS DOS Software e A68K 68000 cross assembler e XLINK 68000 linker locator conversion utility e PC VT VT100 terminal emulator e EDIT MS DOS text editor or equivalent 68000 Programs e KEYPAD provided in 68KMB directory e KEYPAD2 to be written INTRODUCTION This is the fifth in a series of labs to explore interfacing with the 683KMB I O Board 5 is quite different from the boards used in the preceding labs Instead of interfacing to the 68681 on the 68KMB I O Board 5 contains its own peripheral interface IC a 6821 The connection to the 68KMB is through J2 J2 includes the required address decoding and control signals to interface to any 8 bit peripheral interface device from the 6800 family The signals on J2 of the 683KMB are peripheral interface adapter PIA illustrated in Figure 8 16 in The 68000 Microprocessor The connection between I O Board 5 and connector J2 of the 68KMB is illustrated in Figure 11 1 110 VAC AC adapter D VO Board 5 From PC Host computer 68 KMB J3 J1 is used for I O Boards 1 4 J1 68000 CPU Figure 11 1 Connecting I O Board 5 to J2 on the 68KMB 78 The hexadecimal keypad has 16 pressure sensitive switches arranged in four rows and four columns These connect to Port A on the 6821 PIA The complete interface is shown in Figure 11 2 WIRE WRAP AREA Figure 11 2 I O Board 5 Th
68. number of data bits 7 or 8 The second character selects and indicates the type of parity odd even or no parity The third character indicates the number of stop bits always one Cycle through the options until 701 is selected Change the COM port by continually entering c Observe the changes near the bottom of the screen Cycle through the options until COM1 or COM2 is selected conforming to the connection for the RS232C serial interface cable on the back of the system If you are not sure which port to use select COM1 for the moment Change the File Transfer Mode by continually entering Observe the changes near the middle of the screen Cycle through the options until ASCH CTRL Z is displayed 14 13 14 15 16 Return to SETUP A by entering 3 Save the changes just made by entering S PC VT will store these changes in a file called PARAMS DAT Once PC VT is configured it is not necessary to access the setup screen again unless a change is necessary Return to terminal emulation mode by entering ESC Now that PC VT is configured let s verify that it is working Since for this lab we do not have a computer at the other end of the RS232C cable we use some ingenuity to test PC VT As characters are entered on the keyboard PC VT transmits the ASCII codes out the designated COM port Each character is transmitted in serial framed by a start bit a parity bit and a stop bit See Chap
69. offset Although absolute long addressing could also be used this would increase the size of each instruction by one word The ANDI instruction uses a mask of 00000001 to clear all bits except bit 0 which corresponds to the RxRDY bit After the ANDI instruction the entire low byte of D7 0 if RxRDY 0 so the appropriate branch to repeat the test is branch if equal zero BEQ Once a character has arrived RxRDY 1 and the branch test fails The move instruction following BEQ reads a character from memory location 00C007 Receive Buffer A and places it in DO Usually the instruction sequence shown above is part of an input character subroutine or trap Character Transmission When outputting a character TxRDY must be interrogated continually to determine when the last character written has been moved into the shift register At such time the next character can be loaded into the transmit buffer A flowchart illustrating this is shown in Figure 6 3b The following output character sequence is similar to the input character sequence In this instance however we assume an ASCII code has been loaded into DO in advance Note also that bit 2 of the 68681 status register must be interrogated in the output character sequence DUART EQU SOOCOO1 base address for 68681 SRA EQU 2 offset for Status Register A TBA EQU 6 offset for Transmit Buffer A MOVEA L DUART AO A0 points to DUART LOOP MOVE B SRA AO D7 get Status Register A
70. ole Run the new program and demonstrate it to your lab instructor 11 2 CONCLUSION This lab has introduced interfacing to a hexadecimal keypad including scanning the rows and columns of the keypad and debouncing mechanical switches through software 80 81 Lab 12 Interface to a Digital to Analog Converter PURPOSE In this lab a digital to analog converter DAC is interfaced to a 68000 microprocessor through a 6821 peripheral interface adapter Upon completion of this lab students will be able to do the following e Use monitor commands to read and write registers inside a 6821 PIA e Use monitor commands to control a DAC connected to a 6821 PIA e Calibrate the output voltage range of a DAC e Write programs to create waveforms at the output of a DAC e Write programs to create musical tones using a loudspeaker driven by a DAC PREPARATION Prior to the scheduled lab session read the following sections from your textbook e Section 9 13 Analog Output e Section 9 14 Digital Sine Wave Generator e Section 9 15 Music Output From a Digital to Analog Converter 82 MATERIALS Hardware e 68KMB 68000 based computer e J O Board 6 e power supply 12 volt or 15 volt e oscilloscope e screwdriver e PC host computer e R S232C serial interface cable e 20 conductor ribbon cable e amplified external speaker optional MS DOS Software e PC VT e A68K e XLINK 68000 Programs e
71. ost word processors include a file save option to save files as unformatted ASCII text to use a word processor for creating assembly language program files is overkill EDIT is a perfectly adequate editor for creating the source program files for the labs that follow Students who are familiar with MS DOS and have their own favorite editor to use in subsequent labs may skip ahead to step 16 Be prepared to demonstrate to your lab instructor that you are comfortable in editing a text file PROCEDURE PART Familiarity with the Host Computer Environment 1 Power up the host computer and wait for the following MS DOS prompt to appear C gt The exact form of this prompt is controlled by the command PROMPT which usually appears in the system s AUTOEXEC BAT file If this prompt does not appear edit the AUTOEXEC BAT file and insert a line containing PROMPT P G Re boot the system after saving the AUTOEXEC BAT file Ask your lab instructor for assistance if necessary 2 Find out which version of MS DOS is running on the host computer by entering the following command Note User input is underlined C gt VER If the version number is lower than 5 0 ask your lab instructor for assistance 3 Check the current search path by entering the following command C gt PATH 4 A series of directory names separated by semicolons will appear If MS DOS was installed on the host computer following the usual procedure then on
72. our textbook At what address within the program is the variable COUNT located 85 10 11 Using MON68K s memory modify command change the variable COUNT to 000A Re run the program What is the frequency of the sawtooth waveform With COUNT 000A what is the duration of each output step Leave COUNT 000A but change the variable STEP to 0040 What is the frequency of the output waveform What is the duration of each output step 12 3 Make a copy of SAWTOOTH SRC and call it TRIANGLE SRC Put your name and the date in comment lines at the top Modify the new program to create a triangle waveform instead of a sawtooth waveform Demonstrate the new program to your lab instructor 12 4 A program called SINEWAVE is presented in Example 9 14 in your textbook The program creates a sine wave at TP1 by continually outputting data read from a look up table Review the software listing and the description of the program to gain an understanding of its operation The program is in the directory 683KMB on the PC host computer Run the program Connect channel A of the oscilloscope to TP1 and channel B to TP2 The circuit between TP1 and TP2 is a 4 kHz low pass filter see Figure 12 1a Demonstrate the program to your lab instructor 86 12 13 14 15 What is the frequency of the sine wave that you observe on the oscilloscope Using MON68K s memory modify command change the variab
73. ram in Figure 4 2 36 S00900006D796E616D656F 11380003C3C000A227C000080124E42534666F437 11380104E4E53636F7474204D61634B656E7A6981 1078020650D0A00DC 90380007C Figure 4 3 MYNAME HEX Circle the first program byte in Figure 4 3 Circle the last program byte in Figure 4 3 Circle the ASCII bytes in the message string in Figure 4 3 4 2 Transfer the program to the target system Review Lab 2 if necessary 4 3 Make a copy of MYNAME SRC and save it in a file called FUN SRC Put your name and the date in comment lines at the top Modify the source program to display the following message five times with a blank line between each line of output Demonstrate the program to your lab instructor Assembly language programming is fun Make the program executable at address 00A000 5 Demonstrate the modified program to your lab instructor 4 4 37 CONCLUSION Having completed this lab students are familiar with the 68000 programming environment used with the 68KMB 68000 based computer ADDENDUM Batch files are included in the 68KMB directory to simplify the use of A68K and XLINK These include A BATAssemble a source program L BAT Convert an object program to Motorola S records AL BAT Equivalent to A BAT followed by L BAT For example to assemble MYNAME SRC using A BAT the following command is entered C 68KMB gt A MYNAME 38 Lab 5 Programming Problems PURPO
74. ransform it into the terminal for the target computer Most of the time the PC is used to enter commands to the target computer As well it is necessary to transmit a program to the target computer PC VT s File Transmit command is used for this purpose From terminal emulation mode enter CTRL F4 This will bring up a dialog box requesting the name of a file to transmit out the COM port to the device at the end of the RS232C cable We ll demonstrate file transmit mode over the next several steps For the moment return to terminal emulation mode by pressing the ESCAPE key 16 18 19 20 The next several steps require two lab groups in close proximity to work together Obtain a null modem cable from your lab instructor and use it to join together the RS232C cables connected to each system see Figure 2 5 The null modem cable is wired as shown in Figure 2 3 with a DB25S connector at each end Proceed to step 24 if you do not have a null modem cable Figure 2 5 Connecting two PCs through a null modem cable Enter characters on the keyboard of one system They should appear on the screen of the other system If this test does not work either a cable is improperly wired or the configuration of PC VT is not the same on each system Use the steps given earlier to access PC VT s setup screens and resolve the problem Temporarily suspend PC VT and return to MS DOS by entering ALT F The following MS DOS prompt should appear
75. rted to hexadecimal files containing Motorola S records Editing and assembling programs take place on the PC host computer independent of the 63KMB When a program is ready for testing the 68KMB is connected to the PC host computer s RS232C serial communications port Both systems are powered up and the terminal emulation program PC VT is run on the PC host computer This turns the PC host computer into a terminal and enables access to the 68KMB through the monitor program MON68K Programs are transferred to the 63KMB and executed and debugged using MON68K s commands The configuration of equipment is illustrated in Figure 3 1 AC adapter PC 110 VAC RS23 2C serial interface cable 68KMB 68000 CPU J3 Connection to COM port on back of PC Figure 3 1 Configuration of lab equipment 21 When powered up or upon pressing the Reset button MON68K begins executing and outputs the prompt MON68K VX X gt were x x is the version number of MON68K MON68K implements a variety of low level commands to control the 68KMB These will be explored in this lab PROCEDURE 1 Connect the 68KMB to the PC host computer using the RS232C serial interface cable provided The cable connects from J3 on the 68KMB to the COM port connector on the back of the PC host computer see Figure 3 1 Power up both systems The following MS DOS prompt should appear C gt 2 Change to the directory called 68KMB by issui
76. special mention Since the 68000 s data bus is 16 bits wide a program must be split in half and burned into two EPROMs an upper byte EPROM and a lower byte EPROM This is easy to do with the MCT and most other programmers After selecting the P option to program an EPROM a sub menu appears with options to program only the even upper bytes or the odd lower Available from JDR Microdevices 2233 Samaritan Dr San Jose CA 95124 104 bytes from the EPROM programmer s buffer It is advisable to write U or L on top of each EPROM to prevent installing them in the wrong user socket In the following procedure two programs will be burned into EPROM and installed in the 68KMB The first called FIRMWARE is debugged and ready to go This will help us with the initial hurdle of burning a program into EPROM and installing it on the 683KMB For the second program we ll use the ECHO2 program from lab 14 with a few modifications Let s discuss the first program FIRMWARE is simple program that sends the following message to the console ten times Test firmware program The program is in the 68KMB directory on the PC host computer For convenience the listing is given in Figure 15 2 at the end of this lab FIRMWARE is a position independent program which means it can execute at any address Even though it is ORGed to begin at address 0 line 15 Figure 15 2 and it will be programmed starting at address 0 in EPROM once the EPRO
77. symbol linker and locator e Write a 68000 assembly language program consisting of multiple relocatable modules containing code and data segments e Assemble link and locate a 68000 program creating a single absolute output module PREPARATION Prior to the scheduled lab session read the following section from Chapter 4 of your textbook e Section 4 7 Modular Programming MATERIALS Hardware e 68KMB 68000 based computer e PC host computer e R S232C serial interface cable 98 MS DOS Software e A68K e XLINK e EDIT e PC VT 68000 Programs e ECHO e MYLIB e ECHO2 e MYLIB2 INTRODUCTION 68000 cross assembler 68000 linker locator MS DOS editor or equivalent VT100 terminal emulator provided in the 68KMB directory provided in the 68KMB directory to be written to be written A simple program is used in this lab to illustrate modular programming The program is split across two files which must be assembled separately and then linked together to form a single absolute object module The program does the following 1 Output the prompt Enter a command 2 Input a line from the keyboard Store the line in an input buffer Echo each character as it is typed 3 When RETURN is entered echo the entire input line again 4 Repeat When a line beginning with q or Q is entered the program terminates to MON68K The main part of the program is in a file called ECHO SRC and the subrou
78. t is only six bits wide The input port signals are labeled IPO IP5 as seen in Figure 7 2 Each input bit is connected to a single pole single throw switch One terminal of each switch connects to ground and the other terminal connects to an input port pin through a 10K pull up resistor see Figure 7 2 Recall from lab 6 that the base address of the 68681 is 00C001 and that internal registers reside at consecutive odd addresses from this address up to 00CO1F To access the 6868 1 s parallel ports three registers are used These are summarized in Table 7 1 60 Table 7 1 68681 Registers Used With This Lab Read Write Address Name Function Name Function 00C01B IPR Input Port 00C01D OPR_SE Set Output Register Bits al clear pins 00C01F OPR_CL Clear Output Register Bits R set pins Reading input port pins is a simple matter of reading memory address 00C01B Bits 0 5 reflect the state of the input port pins IPO IP5 and bits 6 7 are read as ones For example the instruction MOVE B 00C01B D0 reads the state of IPO IP5 into bits 0 5 of data register DO Writing to the output port is more difficult To clear output pins a mask byte must be written to address 00CO1D with a one in each position where an output port pin is to be cleared To set output pins a mask byte must be written to address 00CO1F with a one in each position where an output port pin is to be set As noted in T
79. tbook MEMORY COMMANDS The most fundamental commands supported by monitor programs are those that examine and change memory locations MON68K supports the following memory commands MD Memory Display MC Memory Copy MF Memory Fill MM Memory Modify MT Memory Test SZ Size of data for MD command Read about each of these commands in Appendix E of your textbook Enter the examples given 23 REGISTER COMMANDS MON68K maintains a copy of the 68000 s registers for user programs The following two commands display and change register contents RD Register Dump R X Register Modify Read about these commands in Appendix E of your textbook Enter the examples given Demonstrate to your lab instructor that you are familiar with MON68K s register commands and memory commands 3 1 PROGRAM EXECUTION Over the next several steps we will enter a simple program into the 68KMB s memory and execute it The program will be entered directly in hexadecimal This is a very primitive way to get a program into memory but it is a worthwhile exercise to gain familiarity with MON68K In the next lab we ll use MON68K s load command to transfer programs written and assembled on the PC host computer Use the MM command to place the following bytes in memory beginning at address 008000 24 Address Content 008000 32 008001 00 008002 52 008003 41 008004 D2 008005 40 008006 D2 008007 7C 008008 00 008009 09 00800A 82 00800B FC 0080
80. ter 9 of your textbook for details Normally a computer is at the other end of the cable and the characters received are echoed back to the terminal on pin 3 We can simulate this by shorting pin 2 and pin 3 together at the end of the RS232C cable This is called a wrap back test Use a metal pen tip or other small metal object e g paper clip screwdriver to short pins 2 and 3 on the DB25P connector at the end of the RS232C cable see Figure 2 4 Be careful not to short the pins to the metal shroud of the connector as well Now enter some characters on the keyboard They should be echoed back and appear on the screen Remove the short and enter some characters on the keyboard again No characters are echoed and nothing displays on the screen This is a simple but very effective test of PC VT s operation 15 17 RS23 2C serial interface cable DB25P Connector Use a metal pen tip or other metal object to short pins 2 amp 3 Figure 2 4 Wrapping output on TxD back into RxD If the test above failed the most likely problem is that the wrong COM port is selected Change the COM port setting using the instructions given previously Repeat the test Ilustrate to your lab instructor that PC VT is working properly Za One important feature of PC VT that is used throughout the labs that follow is File Transmit When the PC host computer is connected to the 68KMB target computer PC VT is run on the PC host computer to t
81. the 4 digit display on I O Board 3 The display should vary from 0 to 255 as the input varies from 0 volts to 5 volts Use subroutines from COUNT4 SRC in lab 9 as appropriate Hint Begin by writing a subroutine that converts a hexadecimal byte to three BCD digits This can be done by first dividing the byte by 100 to obtain the hundreds digit and then dividing the remainder by 10 to obtain the tens digit The final remainder is the ones digit Demonstrate the new program to your lab instructor 13 3 Move the jumper from position X2 to position X1 on I O Board 6 With jumper X1 installed the trimpot is disconnected from the ADC0804 Input is now obtained through the microphone and its associated conditioning circuitry A program called SPEECH is presented in Example 9 17 in your textbook The program has two parts When started at address 008000 speech samples are gathered from the ADCO0804 and placed in a buffer When started at address 00800C the samples in the buffer are sent to the DAC output channel on I O 95 Board 6 Review the software listing and the description of the program to gain an understanding of its operation The program is in the directory 683KMB on the PC host computer Connect the microphone provided to connector J2 on I O Board 6 Run the program and demonstrate it to your lab instructor 13 4 Notes l Adjust trimpot R2 to vary the volume of the output 2 Install an amplified external speaker i
82. tines are in a file called MYLIB SRC Section 4 7 in your textbook contains a detailed discussion on modular programming using the above program as an example Review this section before proceeding 99 PROCEDURE 1 The files ECHO SRC and MYLIB SRC are in the directory 683KMB on the PC host computer Assemble each of these Examine the listing files and answer the following questions What is the name of the code segment What is the name of the data segment What is the first address of the prompt string Note this address is relative to the start of ECHO OBJ What does the symbol CR stand for What is the opcode for the RTS instruction 14 1 2 The file ECHO XLK is a batch file for XLINK to combine ECHO OBJ and MYLIB OBJ into a single executable object program ECHO XLK is also located in the directory 68KMB on the PC host computer Use the TYPE command to examine ECHO XLK Do you understand the purpose of each line in ECHO XLK If not review Section 4 7 in your textbook or ask your lab instructor for assistance 3 Issue the appropriate command to link and locate ECHO OBJ and MYLIB OBJ Review Section 4 7 of your text if you are not sure how to do this What output files were created Examine the link map and answer the following questions What is the absolute address of the beginning of the prompt string 100 What is the first and last address of your program What is the f
83. tion What does the program do Provide as concise an answer as possible There is a much simpler way to achieve the same result as the above program What is it Show the revised program on the right Hint Read about the ROL instruction in Appendix B of your textbook CONCLUSION This lab has demonstrated the operation of the 68KMB and its monitor program MON68K The monitor commands introduced in this lab will be used extensively in the labs that follow 32 Lab 4 Introduction to A68K and XLINK PURPOSE This lab introduces the 68000 cross assembler A68K and the linker locator conversion utility XLINK These are the primary software development tools for the labs that follow A program will be created on the PC using a text editor The program will be assembled converted to hex ASCII format downloaded to the 68KMB and executed Upon completion of this lab students will be able to do the following e Create a 68000 source program using a text editor e Use A68K to assemble a 68000 source program e Determine the opcodes for 68000 instructions by examining a listing file e Use XLINK to convert an object program to a hex file containing Motorola S records e Determine addresses and object bytes of a 68000 program by examining either a listing file or a hex file e Download a hex file to a 68000 target system e Execute a program on a 68000 target system PREPARATION Prior to the scheduled l
84. today s devices with so called RS232C interfaces This is the case with the 68KMB which is configured as a DCE On the 68KMB pin 2 is an input and pin 3 is an output see Figure 2 2 This simplifies the connection with the host computer DTE since a straight through cable can be used 11 DTE DCE host computer 6 8KMB Rx D GND Figure 2 2 DTE to DCE connections It follows that if a DTE connects to a DTE then the TxD and RxD signals must cross over A cable that performs this function is called a null modem A null modem gives the impression that each DTE is connected to a modem This is illustrated in Figure 2 3 Figure 2 3 Null modem connection between two DTEs PROCEDURE 1 Connect the RS232C serial interface cable provided with the 68KMB to the COM1 or COM2 connector on the back of the PC host computer 2 Turn on the PC host computer and wait for the following MS DOS prompt to appear 3 Switch to the directory called 68KMB by entering the following command C gt CD 68KMB 12 If this directory is not present the software from the 68KMB diskette must be installed Follow the installation procedure at the beginning of this lab manual Verify that the files PC VT EXE and HELP DAT are in the directory 63KMB Enter the following command C 68KMB gt DIR P If these files do not appear follow the installation procedure at the beginning of this lab manual Begin PC VT by entering the following command
85. tor conversion utility e PC VT EXE VT100 terminal emulator e EDIT COM MS DOS text editor or equivalent 68000 Programs e MYNAME2 to be written e ALPHA to be written INTRODUCTION The 68KMB s monitor program MON68K includes a variety of built in routines for input output data conversion etc These are accessed through trap instructions As an example the program called MYNAME in lab 4 sent a string of ASCII characters to a terminal by placing the address of the string in register Al and then executing a TRAP 2 instruction MOVEA L MESSAGE Al TRAP 2 There is nothing unique about TRAP 2 in the architecture of the 68000 TRAP 2 provides access to special routines in MON68K but this trap could be used for a different purpose or not at all in other implementations using the 68000 microprocessor This point is mentioned because it is important to distinguish details of the 68000 architecture from details of an implementation the 68KMB As students of computer organization and the 68000 microprocessor we want to get as close to the hardware as possible using machine language or assembly language programs Traps hide details of input output This is convenient for systems programmers however to uncover the details of input output subsystems we want to get inside the low level details of character input output as implemented on typical computer systems such as the 68KMB Asynchronous Input Output The
86. ts of the listing files Be prepared to demonstrate your program with sample data specified by your lab instructor Problem 1 Write a program called SHIFT32 to shift a 32 bit binary number until the most significant bit of the number is 1 The address of the number is defined by the longword variable NUM at location 9000 Store the normalized shifted number in the variable NORM at location 9004 Store the number of left shifts required in the byte variable SHIFTS at location 9008 If the number is zero clear NORM and SHIFTS Sample Conditions Before Address Contents 009000 0000 009002 9100 009004 FFFF 009006 FFFF 009008 FFFF 009100 1234 009102 5678 After Address Contents 009004 91A2 009006 B3CO 009008 0003 Note Test your program with values of 0 FFFFFFFF etc 44 Problem 2 Write a program called LENSTR to determine the length of a string of characters The starting address of the string is contained in the 32 bit variable START at location 9000 The end of the string is marked by an ASCII null character Place the length of the string excluding the null character in the variable LENGTH at location 9004 Sample Conditions Before Address Contents 009000 0000 009002 9040 009004 5555 009040 4142 009042 4344 009044 4546 009046 4748 009048 OOFF After Address Contents 009004 0008 Note Place the ASCII string in your program by enclosing the characters within single quotes after a DC B directive
87. turn to MS DOS To Exit From EDIT Press ALT F to activate the FILE menu Press X to exit EDIT and return to MS DOS 14 15 16 17 18 Verify that the file EXAMPLE TXT has been created and is present in the current working directory Enter the command C LAB1 gt DIR The file EXAMPLE TXT should appear in the directory listing Verify that the contents of the file are as expected Enter the command C LAB1 gt TYPE EXAMPLE TXT The contents of the file as shown in step 11 above should appear on the console Demonstrate to your lab instructor that you can perform the following operations e Open a file for editing using EDIT e Enter text e Move the cursor on character word line or page boundaries e Select a block of text e Move text from one position to another e Copy text from one position to another e Replace sequences of text with new text e Save the edited text to a disk file e Use MS DOS to verify the presence and contents of a text file Delete the example file C LAB1 gt DEL TXT Delete the directiory LAB1 C LAB1 gt CD C gt RMDIR LAB1 1 1 CONCLUSION This is a very brief introduction to MS DOS s full screen editor EDIT A variety of other features and commands are accessible from EDIT s menus Students are advised to experiment with these until comfortable with EDIT Lab 2 Introduction to PC VT PUR
88. ure the EDIT COM program is in a directory listed by the PATH command If it is not edit the AUTOEXEC BAT file to include the path Re boot the system after editing AUTOEXEC BAT 2 The demo program is read into the editor s buffer and appears on the screen Use the arrow keys and position the cursor just after the O in HELLO Enter your name John Doe 3 Save the modified demo program Enter ALT F followed by S 4 Exit the editor and return to MS DOS Enter ALT F followed by X 5 Assemble the modified demo program using A68K s batch program C 68KMB gt A DEMO2 vi A68K assembles the modified demo program and stores the output in the files DEMO2 OBJ and DEMO2 LST 6 Convert the assembled program to Motorola S records This task is performed by XLINK A batch program is provided to reduce the typing Enter C 68KMB gt L DEMO2 XLINK converts the 68000 machine language program in the file DEMO2 OBJ to Motorola S records The output is stored in the file DEMO2 HEX Ls Run the terminal emulation program C 68KMB gt PC VT 8 Press the RESET switch on the 68KMB and enter the load command MON68K V4 4 gt LO 9 Transmit the modified demo program from the PC to the 683KMB CTRL F4 followed by DEMO2 HEX Enter Y when asked if CTRL Z should be transmitted 10 Execute the modified demo program V4 4 gt GO 8000 A welcome message with your name embedded in it is displayed on the CRT of the PC
89. versions TTL RS232C Logic Voltage Logic Voltage high 1 2 4 to 5 volts MARK 3 to 25 volts low 0 0 to 0 8 volts SPACE 3 to 25 volts 52 Since data are transmitted on pin 3 of the RS232C interface the 63KMB is configured as a DCE A straight through cable can be used as long as the terminal host computer at the opposite end is configured as a DTE see lab 2 The address decoding provides access to the 68681 s registers through odd byte addresses 00C001 to 00CO1F In this lab we are only concerned with the three registers shown in Table 6 2 Table 6 2 68681 Registers Address Read Write 00C005 Status Register A SRA 00C007 Receive Buffer A RBA Transmit Buffer A TBA Each bit in the status register has a different purpose as shown in Table 6 3 Table 6 3 68681 Status Register Bit Assignments 7 6 5 4 3 2 1 0 Received Framing Parity Overrun Break Error Error Error TXEMT TxRDY FFUL RxRDY 0 no 0 no 0 no 0 no 0 no 0 no 0 no 0 no 1 yes 1 yes 1 yes 1 yes 1 yes 1 yes 1 yes 1 yes The bits we are concerned with in this lab are TxRDY bit 2 and RxRDY bit 0 TxRDY indicates either that the transmitter is ready to accept a new character for transmission TxXRDY 1 or that the transmit buffer is full TxRDY 0 RxRDY indicates either that a character has been received and is waiting in the FIFO to be read by the CPU RxRDY
90. y 9 MOVING TEXT Use the steps below to move the first line of text entered in step 6 to the end of the file The example text should look like this This the second line of th xample fil This is the last line of th xample fil This is a test of DOS EDIT To Move a Block of Text Select the block of text you wish to move Press ALT E to activate the EDIT menu Press T to cut the selected text to a temporary buffer Move the cursor to the location where you want the text to appear Press ALT E to activate the EDIT menu Press P to paste the text from the buffer to the cursor location 10 COPYING TEXT Use the steps below to make a copy of the last line in the file and insert it at the beginning of the file The example file should look like this This is a test of DOS EDIT This is the second line of th xample fil This is the last line of th xample fil This is a test of DOS EDIT To Copy a Block Text Select the block of text you want to copy Press ALT E to activate the EDIT menu Press C to copy the selected text to a temporary buffer Move the cursor to the location where you want to copy the text Press ALT E to activate the EDIT menu Press P to paste the text from the buffer to the cursor location Practice the move text sequence again by moving the third line in the new text to the end of the fi

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