[Coco] Four floppy drives?

[Mike Delyea]

Cripes, I thought I was doing good getting OS-9 booting from a 3.5 inch
floppy.

On Sat, Aug 1, 2015 at 1:32 AM, Barry Nelson <barry.nelson at amobiledevice.com
> wrote:

> I once had 8 floppy disks running at once on a CoCo. I ran the floppy
> cable to a 4 line to 16 line demultiplexer chip and hooked drive select
> lines 0-2 into the inputs of that chip, I let the side select signal
> through untouched. Then I had 3 floppy cables coming out of the
> demultiplexer, one had lines select lines for drives 0-2 on the pins for
> 0-2, the next cable had select lines for drives 3-5 on the the pins for
> drives 0-2, and the last cable had the select lines  for drives 6 and 7 on
> the pins for 0 and 1. It worked under OS-9. Special OS9 drivers were
> required. Under disk basic only drives 0,2, and 4 were available. I set
> this up for a friend who ran a BBS.
>
> On Jul 31, 2015, at 10:26 PM, coco-request at maltedmedia.com wrote:
>
> > Date: Fri, 31 Jul 2015 15:25:08 -0400
> > From: Arthur Flexser <flexser at fiu.edu>
> > To: CoCoList for Color Computer Enthusiasts <coco at maltedmedia.com>
> > Subject: Re: [Coco] Four floppy drives?
> > Message-ID:
> >       <
> CA+LuDccNzenc1N5oXcTF+EUPw88UBezRMPyfyE8oW_3v4DM77Q at mail.gmail.com>
> > Content-Type: text/plain; charset=UTF-8
> >
> > It is puzzling how you managed to get 4 double-sided drives working.
> > Ordinarily, only 3 would be available.  You have 4 drive select lines,
> but
> > one would normally be used as a side select for double-sided drives.  I
> > vaguely recall an article that described some scheme that recognized that
> > when two drive select lines were simultaneously selected, a fourth drive
> > would be accessed.  Did you do something like that?  Did you modify the
> > Disk Basic ROM?
> >
> > Art
>
>
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