The first entry is an ASCII art generator - and of course the program itself is ASCII art. It takes 24 bit BMP files on the input, and produces a picture using one char per pixel (so use small pictures!). Here is the program, the remarks, and a sample picture to try it on.
The second and third entries are a 6502 emulator that is also able to emulate the Commodore PET. For this it needs the Commodore PET ROM, which is included in one version but not the other. You need to compile the program with the -lcurses option. (Eg. cc -o prog -lcurses prog.c)
Here is the first version - the program, the remarks, the PET ROM, a 6502 test program, a BASIC demo program and finally a compiled-for-6502 hunt the wumpus program. (Check the remarks to see where this program came from.)
And here is the second version - the program, the remarks, the 6502 test program, a BASIC demo program, a shell script to fetch the PET ROM from the internet and finally a compiled-for-6502 chess playing program. (This is actually the chess program from my previous IOCCC entry.)