[Coco] Cassette data format

[Mark J. Blair]

Thank you both. Those were educational posts. I wasn't aware that cassette recorders were ever made without AC bias circuitry. I did find that when I tried a CRO2 cassette in my CCR-81 because it was the only tape I had sitting around, the recorder was not capable of fully erasing a previous recording. Since then, I've obtained some proper regular bias cassettes from eBay. Some were original Radio Shack leaderless C-20 tapes marketed for use in computers, and some were Maxell C-30 leaderless "Communicator Series" tapes.

I was able to record my script's square wave output on my CCR-81 and have the CoCo read it, but I'll generate sine waves in my next version. I'll be revising the script anyway since I found a problem that made it unable to translate one of the .CAS files I downloaded. All of the previous .CAS files I looked at had the data byte-aligned, so I assumed that in my program. The problematic one had the filename block byte-aligned, but the data block and its leader are shifted by 3 bits. So, my next version will treat .CAS files as a stream of bits instead of a stream of bytes. That'll be necessary anyway when I implement a .WAV file decoder, so I should be able to have a common routine parse the decoded bitstream whether it comes in from a .CAS file or a .WAV file.


-- 
Mark J. Blair, NF6X <nf6x at nf6x.net>
http://www.nf6x.net/