Speaking for the Timex/Sinclair community, most of us
use sound-card
 utilities whereby we can load or save programs and/or data using a cassette
 recorder.  For the zx81, there is actually a utility which sends an audio
 signal out the PC's parallel port, to be directly loaded into a zx81 or saved
 on tape for use later.
 If you wish, I could direct you to the authors of these utilities -- one of
 them may be interested in helping you solve this problem.
 Regards,
 Glen Goodwin
 0/0
  
Hmmm, do I understand that first part correctly that you're essentially
using the PC as a cassette recorder?  That *REALLY* appeals to my sick sense
of humor.  Now what machines do I have that can use cassette tapes.... :^)
                                Zane