[Coco] Maximum CoCo Drives (was: Re: Posted this pic for retro innovations)

[RETRO Innovations]

On 1/22/2020 12:41 PM, rietveld rietveld wrote:
> Let's turn this back into a coco topic
>
> is 4 the maximum number of physical drives a coco can have, or has someone ever  patched a DOS  to allow for the use of more drives?
Others can chime in, but the FDC has 3 drive select lines.  As such, I 
would assume one could put a 3-8 decoder on those lines, and, with 
requisite changes to the DOS, use up to 7 drives (leaving 1 selection 
for "no drive selected").  I think I saw an advertisement in Rainbow for 
something that did just this.  Of course, even at 3 drives per 
interface, in an MPI, isn't that 12 drives?

Jim