[Coco] Recovering Fast Cassette Saves

[Arthur Flexser]

On a CoCo 1/2, you can't just load in such a tape at high speed, because only
the ROM operations are at double speed, and saving and loading a tape involve
different mixtures of ROM and RAM processing.  (This DOES work on a CoCo 3,
where both ROM and RAM operations are at double speed in the high-speed mode.)
Another problem is that the pause after the CSAVE or CLOAD for the cassette
motor to reach full speed is halved at the high speed mode, and this may be
insufficient for reliable operation;  giving a MOTOR ON command in advance
solves that.  Using the double-speed mode for tape operations can actually be
advantageous if done correctly, since the speed of tape operations is
conveniently doubled.  My first commercial program was FASTAPE, a utility for
double-speed cassette operations based on this.  It allowed any combination of
saving and loading at high or low speed.  At double speed, the I/O speed of the
CoCo's cassette actually substantially exceeded the I/O speed of the disk drive
of the CoCo 1's contemporary, the Commodore 64, though the cassette of course
lacked the convenient random access to any file on the drive that a disk drive
provides.

Art

On Sun, 20 Jan 2008, 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 ]=-
> 
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