Cassette formats (was: Prices to pay for old computers...)

From: Allison J Parent <>
Date: Sat May 23 21:51:51 1998

<At one time or another, I was struck by the similarity of the CoCo's
<cassette format and the now-ancient Kansas City Standard. Were they
<actually identical? Did RS implement the KCS for the CoCo, or was it
<just something kinda similar? And if TRS-80-->CoCo and CoCo-->KCS,
<does that mean that maybe IBM just adopted KCS instead of making up
<their own format? (A shocking idea, I admit...)

Unless the character rate was 300baud it wasn't true KCS. The only one
I know for sure that was 300baud was the trs-80 L1 basic as L2 was faster
data rate. They could have copied the data format or even the encoding
but I'm fairly sure most were faster tha 300 baud used far less hardware
(usually a output bit or two and an input bit) plus code to make it fly.
I used to use a non redundant version of KCS that I did in software for
8085 and the like at 1200 baud, retaining the self clocking FM that KCS
is. At one point I'd tried pushing and 4800baud FM worked rather well
on a really good mono tape recorder, 10 KC is a resonable upper limit for
good tape and heads even though most go to 12-17khz. As I could count on
at least one edge per bit and if an edge did not occur for 2 bit times
it's was an error (drop out or noise).

Received on Sat May 23 1998 - 21:51:51 BST

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