TalkChess.com

[Ron Murawski]

I started out in 1981 on a Sinclair ZX80. It looked like a door wedge.
http://oldcomputers.net/zx80.html
It had a membrane keyboard that was almost unusable. I added a 32K RAM pack (for $150!). Hitting the membrane keys caused the RAM pack to wobble and would crash the machine. I quickly modified the computer by cutting into the case and added an external full-sized keyboard.

I learned Basic from the excellent Sinclair manual. Basic was not only a programming language, it was also the operating system. Back then you booted to a Basic prompt.

I soon realized Basic was a very slow language, so I learned Z80 assembly language. In the Sinclair you would create a long REM statement, and then poke in your machine code. You could then call the machine code using the following Basic line:
RAND USER 16514
where 16514 was the address of the first REM line. (That's why you needed to put it first, otherwise it got messy trying to calculate where your machine code would be located in memory.)

I remember using Z80ASM to assemble my programs
http://z80cpu.eu/mirrors/oldcomputers.dyndns.org/manuals/z80asm.pdf
At the heart of Z80ASM was something called the 'Dirty Dog' assembler - it was a quick and dirty implementation and programmers were often heard saying "You dirty dog!", hence the name. I kinda remember saying things that were worse than that... I remember disassembling the Z80ASM program and finding a text string right at the beginning saying: "Nosy, aren't you?"

After upgrading my machine to a Sinclair ZX81 (and immediately modifying it to accept my external keyboard), I bought the Sinclair disassembled ROM code and it became easy to call math and I/O functions from assembly language.
http://k1.dyndns.org/Vintage/Sinclair/80/Sinclair%20ZX81/ROMs/zx81%20version%202%20%27improved%27%20rom%20disassembly%20%28Logan,%20O%27Hara%29.html

I wrote a chess move generator in Z80 asm and it did a 7-deep perft in about 10 seconds. But, when I printed out the chess board, it would occasionally 'lose' a piece that the move generator had inexplicably lost. It was a very buggy piece of software and I never fully debugged it.

I did not return to chess programming until 2000.