Loading on the ZX80
Posted: Sat Apr 01, 2023 11:52 am
Well it’s the start of a new month and I have a very interesting discovery to report.
As you will know, Sinclair sold the ZX81 ROM as an upgrade to the ZX80 to enhance the computer’s ability from integer only maths to floating point maths. The downside, it was widely reported at the time, was that programs couldn’t be shared between computers fitted with the different ROM types. But amazingly it actually turns out not to be the case. The program just had to be saved out in a special compatibility mode. Who knew this ability was available for all these years?!
You don’t believe me? Well if you have about 5 minutes spare then try this...
Download this wav recording of such a program:
You can either use real ZX computers or an emulator (I use EightyOne but other emulators equally suitable are available - if using EightyOne, remember to set Options > Tape > Source to be the Wave Loader). Then just try loading the wav directly into a ZX80 fitted with its original 4K ROM and also a ZX80 fitted with the 8K ZX81 ROM (or just use a ZX81 instead since it contains the same ROM) by typing the standard LOAD and LOAD “” commands respectively. Then prepare to feel foolish for having doubted me!
As you will know, Sinclair sold the ZX81 ROM as an upgrade to the ZX80 to enhance the computer’s ability from integer only maths to floating point maths. The downside, it was widely reported at the time, was that programs couldn’t be shared between computers fitted with the different ROM types. But amazingly it actually turns out not to be the case. The program just had to be saved out in a special compatibility mode. Who knew this ability was available for all these years?!
You don’t believe me? Well if you have about 5 minutes spare then try this...
Download this wav recording of such a program:
You can either use real ZX computers or an emulator (I use EightyOne but other emulators equally suitable are available - if using EightyOne, remember to set Options > Tape > Source to be the Wave Loader). Then just try loading the wav directly into a ZX80 fitted with its original 4K ROM and also a ZX80 fitted with the 8K ZX81 ROM (or just use a ZX81 instead since it contains the same ROM) by typing the standard LOAD and LOAD “” commands respectively. Then prepare to feel foolish for having doubted me!