them computer should be 16-bit This is one of those things that depends on the hardware. The PET and its descendants did indeed use one bit in that manner. There are quite full descriptions of the waveforms it generates in several manuals. One-bit sampling is not necessarily a good idea. What you then have is: PET writes to tape nice square signal of well defined timing. Signal comes off tape with rounded corners, noise etc. You sample it at 1 bit and write to a file. Later you read the file on a modern machine and reconstruct the audio. This is a nice square signal, with timing dependent on (a) the distortion of the original recording/playback process, (b) the noise added by tape ageing etc., (c) your sampling at 22 kHz. It goes through some audio system with not necessarily a good bandwidth and arrives at the PET cassette port. The PET then has to interpret it... Worse still if you're using an audio CD. The CD player will be filtering according to what's best for the human ear, not what's best for the computer. My advice: If you're going to do 1-bit sampling, process _immediately_ to try and reconstruct the original signal. That is what the machines do (often in hardware), after all. Then remember that some machines _don't_ use 1-bit encoding. The BBC micro, for example, uses a standard modem chip of the time, and the outputs look (I think) fairly sinusoidal... a to be Agreed. 1-bit sampled audio - or multiple bit sampled audio processed to reconstruct the 1-bit waveform - should be many times more compressible than ordinary sampled sound. In theory, the compressed file need be only a few times the size of the original program, but I doubt this will be achievable. only get an I agree with whoever pointed out that you can use the two tracks of the stereo audio for different programs. Cross talk is negligible. That's 140 min. After all, those of us with reel-to-reel tape have been doing this for years... Audio CD is necessary in my opinion. The point of this exercise is to plug your computer into your sound system and load programs _without_ the need for a modern machine to retrieve archives and things. If it wasn't for copy protection, turbo loaders and the like I'd favour sampling the output of the computer's cassette port... Philip. PS PET and many later C= machines have one more problem: they didn't use standard audio cassette machine, but one with a special Commie board in it and a custom interface.