Southwest Specialty Products 6800 manual

6800 ROM MONITOR VERSON 1.0 USERS GUIDE Southwest Techni cal Products Corporation 219 W. Rhapsody San Antonio, Texas 78116 Copyright 1977, Southwest Technical Products Corporation Scanned and edited by Michael Holley Sept. 17, 2000 Revised Aug. 6, 2002 Southwest Technical Products Corporation Document Circa 1977[...]

1 SWTPC SWTBUG® (SWATBUG) MONITOR ROM One of the features of the SWTPC 6800 Computer System is that the conventional programmer’s console has been replaced with a monitor ROM. The programmer’s co nsole consists of all the pretty switches and lights often found on similar microcomputers that are used to bootstrap the system after power up. The [...]

2 SWTBUG® INSTALLATION SWTBUG® is a MOS device and MOS integrated circuits are susceptible to damage by static electricity. Although some deg ree of protection is provided internally within the integrated circuits, their cost demands the utmost in care. Before opening and/or installing SWTBUG® you should ground your body and all metallic tools c[...]

3 MEMORY EXAMINE AND CHANGE M (addr) The Memory Examine and Change funct ion can be used to enter machine code programs and to display and/or change the contents of memory. The Memory Examine and Change function should be used as follows: 1.) Type M . The computer should echo the M and output a space. 2.) Type in the four digit hexade cimal address[...]

4 The condition codes are as defined below: BIT NO. LABEL CONDITION CODE 0 C Carry - borrow 1 V O verflow 2 Z Zero 3 N Negative 4 I Interrupt mask 5 H Half carry In the above example the condition code of "3C" can be interpreted as follows: 3C 16 = 0 0 1 1 1 1 0 0 BIT 7 BIT 6 BIT 5 BIT 4 BIT 3 BIT 2 BIT 1 BIT 0 Below are two examples of h[...]

5 $R $FF DC FC 6EFD 0100 A042 REGISTER DUMP BEFORE RUNNING PROGRAM $G $R $FF DC FC 6EFD 0100 A042 NOTE R DUMP THE SAME AFTER RUNNING $J 0100 $R $FF DC FC 6EFD 0100 A042 THE SAME AFTER A JUMP $M 010A AT THIS POINT THE JUMP TO SWTBUG CONTROL $010A 7E 3F IS REPLACED BY A SWI. NOTE THE VALUE $010B 50 OF THE REGISTERS AFTER THE NEXT DUMP. $G $F9 FF 00 1[...]

6 A002 à 01 MOST SIGNIFICANT BYTE OF LO WER ADDRESS A003 à 23 LEAST SIGNIFICANT BYTE OF LO WER ADDRESS A004 à 45 MOST SIGNIFICANT BYTE OF UPPER ADDRESS A005 à 67 LEAST SIGNIFICANT BYTE OF LO WER ADDRESS Typing P would turn the punch on and output the specified memory data. A sample punch output is as follows: $M A002 $A002 02 01 MSB OF LOW ADDR[...]

7 $M A048 $A048 01 00 $A049 03 05 $A04A F4 $P $S11300000A0501001EF023FF01A01B351B37022443 $E S105A04800050DS9 $ $ A048 and A049 are automatical ly transferred to A002 - A005 and punched to tape by the E command. A short delay follows the S9 to allow clean load - ins on cassette tape. Appropriate punch on/off commands are automatically sent. TAPE LO[...]

8 A previously set breakpoint will remain and may be changed or removed as described earlier. If, when using the B command, a non - hex value is entered the previous breakpoint will be removed and SWTBUG® control will resume. There are several t hings that one must be aware of when using breakpoints to insure proper operation. 1.) The breakpoint f[...]

9 VECTORED SOFTWARE INTERRUPTS Normally when encountering a SWI (3F) instruction, the computer will display the processor’s registers and SWTBUG® control will be resumed. If desired, the 3F command can be vectored to anywhere in memory, just like the NMI and IRQ interrupts. To use the vectoring capability simply store the service routine address[...]

10 PIA STROBING Use of the Control Interface for Read/Punch - On/Off Decoding SWTBUG® software contains subroutines to send out pulses to unused pins of the PIA integrated circuit on the MP - C serial control interface that can be used for automatic reader / punch c ontrols. These pulses can be used if you are using a SWTPC AC - 30 cassette interf[...]

11 OPERATING THE MP - A PROCESSOR BOARD AT BAUD RATES HIGHER THAN 1200 BAUD When using the MP - S serial interface with an MP - A processor board, baud rate clocks for up to 9600 baud are available from the baud rate generator on the MP - A processor board. The table below shows the baud rates available and from which pin of IC4 on the MP - A board[...]

12 NOTE: This does not mean that SWTBUG® is equipped w ith a binary loader - only certain SWTPC binary tapes that contain a special binary loader (in ASCII) will work correctly. To load the tape simply follow the instructions given for loading an ASCII tape, but keep the reader locked on. SPECIAL NOTES ON USIN G AN ACIA AND PROGRAM MODIFICATIONS M[...]

13 GENERAL RULES FOR PROGRAM WRITING Although for a user program to be functional it need only work with the exact system it was written for, follow ing a few simple rules reduces program modifications for 6800 systems using other monitors. Following these rules will make your programs more professional and versatile. Some general guidelines are as[...]

14 SP (A008) Temporary storage location for the stack pointer. SP is used in the register dump subroutines and by the breakpoint function. PORADD (A00A) This location contains the port address used for S WTBUG’s I/O routines. PORECH (A00C) This byte tells SWTBUG® ‘s input routines whether or not to echo. XHI (A00D) Temporary index register sto[...]

15 INHEX and INCH, temporary storage locations CKSM and both accumulators. If a non - hex value is entered, SWTBUG® control will resume. When BYTE is called as a subroutine, the computer will wait for two hex characters to be entered thru the control port. If a 3C is entered, the results will be as follows: ACC A 3C ACC B CKSM IXR UNCHANGED CKSM P[...]

16 ORG $100 START LDX #TEXT JSR PDATA1 JMP CONTRL TEXT FCB $0D, $0A FCC /HELLO/ FCB 4 END - The accumulator and register status after using PDATA1 is as follows: ACC A Changed during the operation ACC B UNCHANGED IXR Contains the memory location of the 04 CHANGE (E088) CHANGE is SWTBUG‘s memory examine and change function. Change uses a number of[...]

17 CONTRL (E0E3) This MIKBUG® equivalent sequence again resets the stack to A042. PORECH is cleared to enable echo and the subroutine SAVGET is selected to get the correct port number and type. Next, the routines PNCHOF and RDOFF generate punch and reader off commands. A carriage return, line feed, erase to end of line (15 16 ) and a $ is then out[...]

18 IOUT (E240) IOUT is the PIA output routine which outputs the character in the A accumulator. OPTL (E269) OPTL is the service routine that sets up PORECH for I/O on port 0. The appropriate command P, E or L is then selected. PIAECH (E27D) This routine disables the echo on a PIA type interface. PIAINI (E284) This routine is used to initialize PIA [...]