Quote:
Originally Posted by IanBland
Well the easiest way without any hardware would be to play it into the cassette port from a WAV file  |
Well, think that through. Unlike the later Spectrum the ZX81 did not have a specific tape format for loading and saving binary files, so the only thing it could load from tape, technically, was BASIC. Somehow, you have to get the code which your assembler has produced into a format which looks to the ZX81 as though it is a BASIC program.
I don't know if the low level tape routines were able to be called by the user, but if they were then perhaps a short piece of machine code contained in a REM statement could launch a loader utilising the tape routines in ROM to load in raw data. Alternatively a larger REM statement could contain a self contained 'loader' which would load the 'raw' code in from the tape.
In more recent years we have seen the emergence of tapes represented by files and sometimes converted back into tapes, so examination of how the .TZX and .P file formats are constructed may yield clues.
I think you are probably right that the larger and more prolific software houses started to use hardware emulator / development systems, although probably more towards the peak of the 8-bit era, your Spectrums, C64s, Amstrads, BBC Bs, etc.