TS1000 is the American version
of the ZX81 and the first Timex Sinclair computer. It is 100% ZX81 compatible. In fact,
early models had a ZX81 circuit board. Two 4x1K RAM chips replaced by single 8x2K RAM. It
looks like a ZX81 except it has a Timex/Sinclair logo where the Sinclair logo appears on
Timex have put 2K RAM instead of 1K.