[Coco] high density floppy controller mods

Mike Pepe lamune at doki-doki.net
Sun Aug 6 10:25:12 EDT 2006

farna at att.net wrote:
> Joel, what puzzles me is why no one has ever attempted to use one of hte PC multi I/O chips to build a no halt controller. The chips with floppy, IDE, parallel, and serial ports built in. I recall the cards for ISA slot machines being rather small. I'm not sure you can get 8 bit MIO chips anymore, but surely a buffer arrangement for a 16 bit chip could be worked out. The only problem I can really see is that it may only work with OS9 and not DECB due to the limited room to modify the ROM code. If only the disk controller worked for DECB that would be an accomplishment though. No-halt operation is only good for OS-9 anyway. I'm sure these chips are available, some of the single board controller/computers use them. There are quite a few 16 bit single boards, not sure if any 8 bit are made anymore. 
> --
> Frank Swygert
> Publisher, "American Motors Cars" 
> Magazine (AMC)
> For all AMC enthusiasts
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I'd say the major reason is compatibility. None of those super-IO chips 
are WD-compatible. Also physically most are in small packages which are 
more difficult for the home-based hacker to play with than good old DIPs.

For OS/9, of course, compatibility is less of an issue.

Also those super-IO chips are very ISA-bus dependent, so it can be a bit 
tricky to get it mapped.

I was going to try something like that, but I was never able to find a 
small quantity of the controller chips. Intel has (had) some interesting 


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