[Coco] tape format
operator at coco3.com
Mon Nov 17 22:17:07 EST 2008
At 09:02 PM 11/17/2008, you wrote:
>For some reason, I thought the Coco did have 1500 Hz cassette system. I
>seem to remember it being exactly 5 times faster than the Commodore.
>In any event, what was the speed of the Coco cassette?
They claim an average of "1500 baud" because of the random assortment
of 1200 hz and 2400 hz sine waves.
The 2400 hz wave is only output once on a CoCo. Some old vintie
systems output 2 of the 2400 hz waves so the duration is the same as
the 1200 hz wave. To me this would probably give better reliability
with cheap tapes depending on the formula, averaging, and testing
used in the load-back code. The problem has always been the drag on
the tape causing the record and play rates to both vary slightly over
time, like if you held your finger on one of the rotors ever so
slightly similar to slowing down an LP record platform. This is why
data stored in blocks loads back more reliably. The loader gets a
chance to get back in sync more often.
I just think that with our modern way of thinking and time-tested
experiments over the ages, that a much faster and reliable tape audio
format could be created that would blow the lid off the old format,
even using cheapo tapes. I *might* save all that for a rainy day
after cocotape.exe is done, but I doubt it.
Btw, cocotape will have a ~1mhz and ~2mhz save option so you can type
POKE 65495/7,0 on the CoCo and load twice as fast from the PC since
it's a perfectly steady audio stream with no tape drag or drop
factor. The default will be the ~1mhz speed, ofcourse.
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