[Coco] 26-3029 floppy disk controller.

[jdaggett at gate.net]

Mike

The Coco 3 actually copies the ROMs from $C000 through $FFDF into ram.  
There modified and RSbasic is ran from ram that is mapped by the MMU at 
$C000 to $FFDF. It is posible, via the MMU, to swap between ram and rom 
at $C000 to $FFDF. 

james

On 17 Jan 2006 at 14:58, Mike Pepe wrote:

Date sent:      	Tue, 17 Jan 2006 14:58:26 -0500
From:           	Mike Pepe <lamune at doki-doki.net>
To:             	CoCoList for Color Computer Enthusiasts <coco at maltedmedia.com>
Subject:        	Re: [Coco] 26-3029 floppy disk controller.
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> Roger Merchberger wrote:
> > Rumor has it that Paul T. Barton may have mentioned these words:
> > 
> >> Just received a 26-3029, where the '9' has been added
> >> as a sticky tag. Inside is the non-gold PCB, with
> >> a MB8877A controller chip (40-pinner) also has
> >> the socketed WD9216 data separator.  Wow, this one
> >> has been a target, not hoped to ever see. It looks
> >> useable but has not been tried. Socketed ROM
> >> SCM92128P, probably a 27128-OTP type, 24-pins.
> > 
> That is indeed a Motorola-pinout mask ROM with 8K of Disk Basic, not a 
> 27128.
> 
> Some of the later "short" cart controllers have a 28 pin 2764 compatible 
> ROM.
> 
> As a side note, a CoCo 1 or 2 has 16K of external ROM space. A CoCo 3 
> can have 8,16,or 32K. By default, however, the address range $E000-$FDFF 
> is used by the "super" basic, leaving 8K for external ROM.
> 
> I suppose this means that it's not possible to use a 16K 3rd-party disk 
> BASIC ROM on a CoCo 3.
> 
> 
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