Recent Finds & Thoughts

From: Mark <mark_k_at_iname.com>
Date: Wed Nov 25 11:26:01 1998

On Sun, 22 Nov 1998 Gareth Knight wrote:
>Marvin wrote:
>>Having *finally* gotten a CD-R unit hooked up, it occurred to me that
>>perhaps recording all the cassette data tapes to CD would be a worthwhile
>>thing to do. Has anyone else tried this? I would think it would be
>trivial
>>to hook up a stereo to computers, and thus load both data and programs.
>
>You mean record the audio on to a different track? Yes, it certainly is
>possible. There was a commercial device out for the Sinclair Spectrum in
>1990 that included 30 games on one CD. I think it was made by Codemasters.
>I've only seen it once at a car boot sale but it appeared to be a basic to
>be a basic CD player with some leads to plug into the tape port.

That's what I understand it consists of. A very high speed turbo-loading
routine is used; tapes would have trouble coping with this. The first track is
probably a normal-speed file containing the loader code, and the other tracks
would be the games recorded at high speed. (Can anyone confirm this?)


I have many old computer cassettes, and have been thinking of recording them
onto a computer in order to preserve their contents. The signal from computer
tapes oscillates between two levels, right? This being the case, it should be
possible to record them using 1-bit sampling. Perhaps record with 8- or 16-bit
sampling and then convert down to single bit.

Are there any programs to do this conversion? I imagine the equivalent of a
Schmitt trigger (in software) would work. What about playing back a 1-bit
audio signal? Are there any standard audio file formats that can be used to
store 1-bit data?

The final 1-bit audio files should be highly compressible, so they could be
archived with zip etc. to reduce size.

If sampling at 44.1kHz, the uncompressed 1-bit sample would use about 5.4K per
second. For a five-minute tape, that comes to under 1.7MB. Sampling is of
course the best way to preserve software, rather than converting the files
themselves; with a sample an exact duplicate of the original cassette can be
created, and things like copy-protection and turbo loaders are no problem.


Actually recording tapes to audio CDs is quite wasteful since you can only get
70 minutes or so on a CD (an issue if you have hundreds of cassettes). My
approach would be to archive tapes as described above; of course burning an
audio CD is useful for transferring the data back to the source computer.


-- Mark
Received on Wed Nov 25 1998 - 11:26:01 GMT