[Coco] tape format

[Roger Taylor]

At 09:02 PM 11/17/2008, you wrote:
>Hi Roger,
>
>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?
>
>John

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.

-- 
Roger Taylor

http://www.wordofthedayonline.com