Stuff done at Cat's Eye Technologies on older computers, or more often, an emulation of such a computer on a modern computer instead.

Apple II

A home computer of old. You may have heard of it?

  • Apple Befunge

    Apple Befunge is a variant of Befunge for the Apple ][+ which resembles Befunge-93, with some extra Befunge-96-esque instructions and some Apple ][+-specific instructions.

Commodore VIC-20

A home computer of old. You may have heard of it?

  • Dungeons of Ekileugor

    Dungeons of Ekileugor is a roguelike written for the Commodore VIC-20, which, despite the limitations of that platform, supports a respectable set of the usual "dungeon furniture": reasonably generated dungeon levels with tunnels and rooms whose contents are hidden until you enter, monsters, treasure, potions, traps, chests, combat with experience points, etc.

Commodore 64

A home computer of old. You may have heard of it?

  • Bubble Escape

    Bubble Escape is a video game written for the Commodore 64 where the player must guide a bubble through a multi-screen maze. It was originally designed and implemented in Commodore BASIC 2.0 in the mid-80's, and rewritten in 6502 assembly language in the late 00's. The assembly version was pared down so that (crunched) it fit into 2K, christened "Bubble Escape 2K", and submitted to the Mini Game Compo 2009 where it won first place in its class.

  • DiskSumo

    DiskSumo is a program to transfer disk images off a Commodore 64 over the RS-232 port via the XMODEM protocol at 300 baud.


    SITU-MON is a machine language monitor for 6502-based systems, written (by hand!) during RetroChallenge 2015/07 and entered into an emulated Commodore 64 using SITU-PAN.


    SITU-PAN is a front-panel switches simulator for the Commodore 64. It displays 8 virtual LEDs and 8 virtual dip switches on the screen. The LEDs display the bit pattern at the current address in memory. Via the keyboard, the switches may be toggled, a new bit pattern written into memory, and the address advanced. In this way, machine code programs may be entered into memory, and then run. SITU-PAN was written during RetroChallenge 2015/07 for the purposes of entering SITU-MON into an emulated C64.


    SITU-SOL is a vaguely Forth-like language which was designed and implemented (by hand!) during RetroChallenge 2015/07, and entered into an emulated Commodore 64 using SITU-MON.

Amiga 500

A home computer of old. You may have heard of it?


    An operating system of old; you may have heard of it?

    • Shelta

      Shelta is an extremely minimal Forth-like language with barely any semantics; it relies on inline machine code to write anything resembling an actual program in it. In the spirit of compilers for languages such as FALSE and brainfuck, a Shelta-to-8086 compiler was implemented (with help from Ben Olmstead) in less than 512 bytes of 80286 machine code. What's more, it's also been bootstrapped — that is to say, a Shelta compiler was written in Shelta, which was compiled with the original compiler, and then compiled again with the resulting compiler, producing a wholly self-hosted executable!

    • ILLGOL

      ILLGOL is a joke language which parodies the sort of language designed by the sheer fact that a compiler for it has been hacked together.

    Z80 machine code

    A central processing unit of old. You may have heard of it?

    • Mildred

      Mildred is a 4MHz Z80-based homebrew computer with 40K of memory (8K EEPROM, 32K SRAM.)