[Coco] Radio Shack 26-3022 FD controller mod

[Gene Heskett]

On Friday 05 December 2014 12:13:17 Kandur did opine
And Gene did reply:
> Thank you. Would this work?
> http://tinyurl.com/nm4lwhf
> 
> Kandur

I'd get them regardless, its  a good controller, 100% compatible with the 
1793 but IIRC its a CMOS chip, very low power.

I don't recall if it needs +12 volts (that's only to power the data 
decoder in the 3022) and it it can be set to produce and receive a 
500kb/sec data rate, then it would be a chip swap and a crystal change to 
make almost any of our controllers in to an HD controller.

But it might need a socket adapter because the 1773 is a 28 pin chip 
whereas this one is a 40 pin chip IIRC.  I have an aftermarket controller 
someplace in my midden heap that has one of those in it.

The possibility might make it just a crystal switch change. Or even 
software if there is a spare latch gate on the board.  Or a register in it 
to select mode? I had a data sheet, about a 4 page thing on that chip, 
someplace in my midden heap.

I don't use that controller because its not a no-halt. But a 6061 and a 
couple latches could fix that, if it would fit inside the case.  Doubtful.

> Friday, December 5, 2014, 8:26:13 AM, you wrote:
> > On 05-Dec-14 08:21, Kandur wrote:
> >> This controller may need 12V to work properly.
> >> I haven’t got a Coco-1, and don't have an MPI either.
> >> When plugged into the Coco-3 directly, the command:
> >> 'dir 0' and 'dir 2' spins up the first drive,
> >> 'dir 1' and 'dir 3' spins up the second drive.
> >> The switch setting makes no difference.
> >> 
> >> Kandur
> > 
> > That nice Ceramic Western Digital FD1793B-02 needs 12VDC.
> > 
> > Replace with the Fujitsu MB8877A.
> > 
> > MarkO


Cheers, Gene Heskett
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