[Coco] Disk drive question

[gene heskett]

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.

> 

> http://www.reocities.com/idezilla/CoCoZilla/hdtext.html

> 

> 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?

> 

> HH

> 

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 
though.

??  Does anyone know where the 8877 can be obtained today?

Cheers, Gene
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