TalkChess.com

[Jan Brouwer]

I wrote my first chess program in hex code on a Ohio Scientific Superboard computer. It must have been around 1980, but I don't remember the exact year. The computer had a build-in Basic interpreter in an EPROM of a few Kbyte, and you could also modify bytes in memory by specifying an hex memory address and an hex value.
First I wrote the 6502 assembly code on paper, translated it by hand to machine code, calculated al the relative jump offsets, double checked everything, poked the program into memory, and ran it. Either something was displayed on the screen (which was an old black and white TV set which has such low light output that I had to close all the window curtains to be able to see anything), or nothing had happened, and I had to recheck my code on paper, trying to figure out what was wrong.
Things went a bit smoother when I was able to save programs to an audio cassette recorder, but that was later.
The program had a material only evaluation and no quiescence search, but it did have alpha-beta search, and already searched about 5 plies deep.
This was also the time that the (dutch) HCC Nieuwsbrief magazine ran a series of articles about computer chess.
I still have the Ohio Scientific Superboard, and I think I also still have the handwritten assembly / machine code somewhere.
I may also still have a little booklet with the assembly source code of H.G.'s Userpator program.

Jan