Done any retroprogramming recently? Let's hear about it!

I mentioned typing in a Pi program, and then writing a simple primes program, in Pi and more at The National Museum of Computing

… and I thought it would be great if everyone could share their most recent, or most interesting, retro-programming story. Maybe you typed something in from a magazine? Or wrote a few lines into an emulator just to test an idea? Or toggled some code into a front panel in your basement?

Just for illustration, this impossible display on a beeb emulator is a one-line type-in from this thread;

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My most recent retroprogramming of note was writing a checksum routine in C to checksum some TU-56 boot image files for a PDP-11 on a PC that was serving as an emulated TU-56 tape drive, then writing the same checksum algorithm (a simple one’s complement Internet-style checksum) in PDP-11 machine code to be toggled into the front panel so that I could verify that the (serial) TU-56 transfer was successful and error-free. It was a fun exercise that took only a few dozen lines of instructions, hand-assembled on a sheet of quadrille graph paper. :slight_smile:

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Well, right now, actually.
Writing a program to read (and maybe write) CF cards on my RC2014.
Wrestling with BDSC on CP/M and realizing it seems to have max 8 characters in variable names…


A whole 8! That’s 2 more than DEC gave ya. :wink:

Does bringing up a “new” 6502 system from scratch count?

However “retroprogramming” … Part of my system needs a filing system, so I used Apple ProDOS as a reference to implement the filing system for my 6502 - it could be said that I cheated here as I wrote it in C on an Atmega MCU rather than in 6502 assembler.

Back to the 6502 - I wrote a small operating system for it - however, again I based it on something else - the Acorn MOS on the BBC Micro computers.

So here I have a “retrobrew” system, with an Apple flavour filing system that can run Acorn software. (e.g. BBC Basic) It’s somewhat weird, but it works. (and it can also run Applesoft too).