[Coco] Another cload post for Diego [ Recovering Fast Cassette Saves]

Arthur Flexser flexser at fiu.edu
Wed Sep 5 03:35:10 EDT 2012


Those pokes won't help with I/O errors;  changing the cassette
parameters in this fashion would cause a tape recorded at normal speed
to not load at all--the file would just be skipped over, probably, and
not be recognized as data.

On a CoCo 1/2 a tape recorded at high speed cannot be read back at
high speed because the high speed poke doubles the speed of ROM
operations without affecting the speed at which RAM code is executed.
Since the csave and cload commands involve different proportions of
ROM vs. RAM code, the timing for one won't work with the other.

On a CoCo 3, though, reading back at double speed should work if the
tape was recorded at double speed on the CoCo 3, provided you start
the motor a bit in advance to compensate for the fact that the
get-the-tape-movement-up-to-full-speed pause will be halved.

Art

On Wed, Sep 5, 2012 at 3:23 AM, Willard Goosey <goosey at virgo.sdc.org> wrote:
> I could swear I have more information about this tweak but I can't
> find it. :-(
>
> Again, I've never tried this, I found out about it long after I'd
> moved all my coco stuff off tape.
>
> This specifically refers to csaves made in hi-speed, but I could swear
> either this (sometimes) works for cload IO errors or there's another
> set of numbers for bad saves made at regular speed.
>
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> Rogelio Perea wrote:
>
>>Was browsing the December 1985 issue of The Rainbow and came across a 'hint'
>>from a Ryan Devlin (Louisville KY). According to his note, the following
>>string of commands would allow a Basic program to be loaded back into the
>>CoCo *after* the program had been saved to tape with the CoCo in high-speed
>>mode:
>>
>>POKE 143,8:POKE 149,24:POKE 145,4:CLOAD
>>
>>The days when I relied with cassettes to do my CoCoing are long gone, but
>>during those times I did save a couple of programs forgetting to kick back
>>the CoCo into its normal speed. I took those files as 'lost' saves, trying
>>to retrieve the file keeping the CoCo sped up proved unreliable.
>>
>>Just curious at what the line above does. Is it altering a timing loop?.
>>
>>
>>-=[ Rogelio ]=-
>>
>
> Those are the bytes that contain the 1200/2400Hz partition time, upper
> limit of 1200Hz, and upper limit of 2400Hz.
>
> Seems to me it would be much easier to just read the tapes in Fast mode,
> but maybe that doesn't work.
>
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> --
> Willard Goosey  goosey at sdc.org
> Socorro, New Mexico, USA
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>   -- R.E. Howard
>
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