It was 1972 or 1973 and I was about 13 years old… and I got access to a computer. It was an Elliott 903C programmed with 8 kilowords of (18-bit) ferrite core memory, and programmed with paper tape, and about the size of a large desk.

I wrote a few tiny programs, then I wrote a program to do a simple simulation of gas molecules in a 2D box. I essentially reduced the problem to a cellular automaton… but I made the rules a bit too trivial, and I never ended up seeing some really interesting phenomena that I discovered for real about 10 years later.

Another program I wrote (that I was rather proud of) was a paper tape loader. The tape (which was sometimes mylar rather than paper) got read by an optical reader at quite high speed… but there could be a problem if a little piece of confetti got stuck in a hole in the tape. I wrote a program that used error-correcting codes (though I hadn’t heard of those then) to correct single-hole errors, and detect bigger ones… then let people just pull the tape back in the reader and re-read a section….