[Coco] Disk drive question
gheskett at wdtv.com
Sun Jan 22 11:34:31 EST 2012
On Sunday, January 22, 2012 11:28:52 AM hhos at st-tel.net did opine:
> > Sorry, it was the somewhat rare 26-3022 drive controller that required
> > 12v.
> > The 26-3029, FD-500/501/502 controllers were 5v. There is a rather
> > involved
> > hardware hack to make the 26-3022 capable of addressing the 1.44 Meg
> > floppies too. For most practical use any drive works with any
> > controller.
> > Bruce W.
> This is a link to instructions for that hardware hack.
> I have not tried it, but without going through all of this, I understand
> that just dropping in a 8877(A) chip, to replace the WDC1793 in the
> original Tandy controller, will eliminate the need for +12VDC. Can
> anyone confirm this?
It may be slightly more complex than that, as in switching a 12 volt pin to
have it wired for 5 volts. Having looked at its specs (I even had a sheet
around here someplace) I also got the impression it would also work at 500
kilobaud allowing the use of many of the more modern drives. I have
encountered 3.5" drives that will not function at all with the coco's 250
kilobaud controllers. A full megabaud or even 2 is likely beyond its reach
?? Does anyone know where the 8877 can be obtained today?
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