ZX80 / ZX81

The Sinclair ZX80 was one of the first tiny ‘home-computers’. It had a Z80 processor in it, one of the predecessors of the later 8086, 80186, 80286, 80386, Pentium, etc, etc. Also on this machine I learned a lot about assembler programming, amongst others through the magnificent book “Programming the Z80” by Rodney Zaks. This machine had 1K (1024 bytes) of internal memory which could be expanded by an expansion pack, giving us 16K of extra storage!

Together with a dear friend of mine (who is in our Father’s house now) we did program a whole Star Trek game, filling up this enormous amount of memory!

A year later came the:


The Sinclair ZX81 which was a minor improvement on the ZX80. It featured a new ROM containing the new code with some improvements (amongst others a “slow” and a “fast” mode).



I didn’t buy a  ZX81, but just got me a set of parts and a new ROM with which I converted the old ZX80 to a ZX81.

So now I had a “beast” in the old case… 🙂