[Coco] 26-3029 floppy disk controller.

[Arthur Flexser]

On Tue, 17 Jan 2006, Mike Pepe wrote:

> Arthur Flexser wrote:
> > On Tue, 17 Jan 2006, Mike Pepe wrote:
> > 
> >> 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.
> > 
> > It certainly is possible, as anyone who has used Extended ADOS-3 can attest.
> > Super Extended Basic is temporarily switched out of the map whenever it is
> > necessary to access ROM addresses in the $E000-FEFF range.
> > 
> > Art
> 
> Hi Art (and Jim too)-
> 
> I suppose this is a feature of ADOS3- or other 16k CoCo 3-aware DOSes? I 
> don't think there's a way for the CoCo3 to do this on its own.
> 

I'm not actually aware of any other CoCo 3 DOSes besides Extended ADOS-3 that
use a 16K disk ROM and switch $E000 and up between ROM and RAM as needed.  The
CoCo 3 does something similar "on its own" in the process of booting up,
temporarily switching in parts of its 32K internal ROM that are mapped out once
the boot up sequence is complete.

Art