[Coco] high density floppy controller mods

Joel Ewy jcewy at swbell.net
Sun Aug 6 21:22:38 EDT 2006

You don't know how convenient your reply was, James.  Digging around in
my parts drawers I found (qty)7 2797s, a 1797b, and 2 1793bs.  I was
wondering whether these were compatible with the 1773, and thinking I'd
have to dig back through this thread to see what the other chip was in
the early CoCo controllers aside from the M8877.  Mind you I'm not sure
I will actually do my own FDC, but seeing as I have a small supply of
the main chip, the temptation to make the attempt is stronger.  And
Mike's success with his modification is certainly inspiring.  Now, where
am I going to get more of those data separators?


jdaggett at gate.net wrote:
> Joel
> IF y ou intend to redo the disk controller or an ISA buss motherboard t hen 
> consider the WD2793/2797 FDC instead of the WD1773. It is software 
> compatible and is a single chip 5V solution. Like the 1793 and M8877 it will 
> do HD 1.44 Meg floppies. 
> Also interfacing the coco expansion buss to a fu ll blown ISA 8 bit buss 
> would not be that terribly difficult to do. A CPLD with sufficient IOBs will do 
> very nicely. 
> james

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