After catching up with Ken Stone a few weeks back I thought I’d take on the task of disassembling and commenting on the original MON1 ROM which I wrote back way back in 1982-83.

I still have a way to go with commenting and labelling the games: NIM, LUNAR LANDER and INVADERS and the TEXTBANNER and TUNEPLAYER but they’re all underway.

All of the tunes, text strings, frequency and 7 segment tables are there.

I used to be quite fluent in Z80 opcodes back in those days but moved on the other things subsequently. With my trusty Rodney Zaks in hand I jumped back in and it’s mostly back. Plus I’m pretty certain that I learned a few new things too along the way.

It’s really quite cool to see code that you wrote 35 years ago–and only had a vague recollection of–come back to life. I only once saw this listing printed out but that was on thermal paper and that faded away after a fairly short time.

This stuff was all hand coded and those (few) hexadecimal relative jumps and subtractions were done without access to a fancy calculator. I didn’t get my hands on a real assembler until I got a Microbee a year or two later.

https://github.com/jhlagado/TEC-1

If you have absolutely no idea what I’m talking about, start here

https://en.wikipedia.org/wiki/TEC-1

https://plus.google.com/u/1/+JohnAHardy/posts/j8wxTwBhSUf

https://plus.google.com/u/1/+JohnAHardy/posts/WZ8HzrkBqMf