[Coco] high density floppy controller mods

[jdaggett at gate.net]

Most all the super IO chips like the 82C493 and others, the FDC controller is 
based on the 8277. That includes the NEC765 chip. 

IF you wanted a more sufficient DIP40 chip try u sing the WD2793/7 chips. 
They are still available for around $7. No change in software except for HD 
disk access. 


james


On 6 Aug 2006 at 10:25, Mike Pepe wrote:

> 
> 
> 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
> > http://farna.home.att.net/AIM.html
> > (free download available!)
> > 
> 
> 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 
> ones.
> 
> -Mike
> 
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