My first java program is an attempt to relive the days I spent maintaining a Lockheed Electronics Company minicomputer installation in an old electricity generating station. I had a little bit to do with this machine around 1978. There was two of them in a failover configuration with the standby machine available for program and data development.
As of March 2021, the documentation that I used, is currently available on archive.org, and the main document reference used for my code here is Lockheed MAC-16 Computer Reference. Unfortunately some errors exist in this Jan70 version and there have been several versions of this reference, released over the period from 1968 to 1971.
A prerequesite for running this emulator is having java installed.
One side effect of sticking to standard java is that console input is line based and the designed I/O for the teletype on this computer is character based. To get around this, while running the emulator, after a line of characters is inputted, I drop the terminating enter code, and enter needs then to be sent on its own line. This means twice the number of enter has to be typed.
In the main program of the machine monitor there are several commands.
$ java mac16/Monitor MAC-16-emulator Copyright (C) 2021 Alan Electron This program comes with ABSOLUTELY NO WARRANTY (for details type 'w') This is free software, and you are welcome to redistribute it under certain conditions (for details type 'c ') * m 0100 0100 0000 d304 0100 D304 0101 0000 6305 0101 6305 0102 0000 n 0103 0000 n 0104 0000 5555 0104 5555 0105 0000 * o 0100 O 0100 0100 D304 LDA P 104 0101 6305 STA P 105 0102 0000 HLT 0103 0000 HLT 0104 5555 JMP X 155 0105 0000 HLT 0106 0000 HLT 0107 0000 HLT 0108 0000 HLT 0109 0000 HLT 010A 0000 HLT 010B 0000 HLT 010C 0000 HLT 010D 0000 HLT 010E 0000 HLT 010F 0000 HLT q * g0100 Halt instruction * o 0100 O 0100 0100 D304 LDA P 104 0101 6305 STA P 105 0102 0000 HLT 0103 0000 HLT 0104 5555 JMP X 155 0105 5555 JMP X 155 0106 0000 HLT 0107 0000 HLT 0108 0000 HLT 0109 0000 HLT 010A 0000 HLT 010B 0000 HLT 010C 0000 HLT 010D 0000 HLT 010E 0000 HLT 010F 0000 HLT q * q $
I have discovered the assembler engine is some sort of weird interpreter object code. After some single stepping through the engine routines, I have arbitarily allocated some operation code mnemonics and added them to the DEVSYS listing. Those of us that had a bit to do with the Motorola MC6800 or M6809 processors might recognise some of my choices for the mnemonics.
I still haven't managed to get the DEVSYS coresident development system to function properly. The editor is difficult to enter text source, and the LEAP assembler is unable to function correctly. I have attempted to debug the assembler but I am still unsure if my emulator, or the DEVSYS program is at fault.
Here are my mnemonics I have determined so far LEAP Interpreter Programming Manual.html
| Usage | Addresses |
|---|---|
| LEAP interpreter engine | 0249-0294 |
| Interpreter routines | 0295-03E2 |
| Interpreter variables | 03E3-0472 |
| Interpreter read write memory | 0473-04FB |
| LEAP code | 04FC-0D02 |
| Buffer for assembler source code | 0D03-0E3F |
| Support routines | 0F00-0F5B |
| Mnemonic lookup table | 12C5-13FF |
| Text Editor | 1400-16FF |
There is now a build.xml included so the ant application could be used to produce the jar file.