Originally posted by fiath
Are you sure? I seem to remember having a lot of trouble doing this. Even typing them in by hand didn't work.
Also ZX80 on ZX81 didn't work IIRC.
Spectrum -> ZX81 Certainly not backwardly compatable
ZX81 -> ZX80 were compatable, if you bought the 8K ROM and replaced the old 4K rom in your ZX80. Sinclair did sell them for this purpose. But ZX80 only worked in good old 'fast' mode (if anyone remembers that little 'quirk' of the ZX81!) - so most games which involved animation were a waste of time. Could play the adventures though...
Did hear of someone who put the old ZX80 rom into a ZX81 (from a kit) and it worked fine. Pointless, but fine.
Oh the days...