more than one :)
That wasn't as hard as another 'just for fun' project. I invented a 6502 based computer, wrote an emulator (well enough to get a display up and read the keyboard) and then wrote a BASIC interpreter for it in 6502 assembler.
(
Lumpbucket tekcubpmuL,
Tue 18 Nov 2003, 11:55,
archived)