[ataylor284_]

I own a Gakken GMC-4 microcomputer, which appears to be a remake of the FX-System. It's a fun little 4-bit computer with a hex keypad for input. For output, there's 7 LEDs, 1 7 segment digit lcd, and a speaker.

It has 16 instructions, one of which is an escape code to a further 16 built-in IO routines. It has 96 4-bit words of actual memory plus some memory mapped registers. Loads and stores can only target the data segment, the top 16 words in memory; it has one 4-bit wide index register that allows indexed access as well.

It's a fun challenge to do something interesting in that constrained environment, but since there's no non-volatile storage of any kind, you have to tediously key in (admittedly necessarily short) programs each time it's powered up.