[Coco] Maximum CoCo Drives

Alex Evans varmfskii at gmail.com
Thu Jan 23 11:20:17 EST 2020

There were people who did hacks to address as many as 15 sides using
the standard controller. There are also ways to modify some disk
controllers for the CoCo to allow for more than one controller. All of
this requires some custom software for dealing with the drives, but if
you use OS-9 this isn't really that big an issue.

On Thu, Jan 23, 2020 at 7:12 AM Francis Swygert <farna at att.net> wrote:
> There are only four drive select lines on a CoCo disk controller, 0-3. The CoCo was set up to from Tandy to handle four physical single sided drives, 35 track. To use double sided drives you lost one of the lines, as it was used as the side select on IBM computer drives (double sided), so only three double sided drives could be used. To go out to 40 tracks (or more) required a DECB modification. ADOS allowed both double sided and 40 track. While DECB couldn't use more than 40 tracks, 80 track drives could be used with OS-9 and the correct drivers.
> I had my custom cased CoCo with two double sided 40 track 5.25" floppies and one 80 track (720K) 3.5" floppy. And a small SCSI hard drive for OS-9. Never really used the HD or 80 track much (never used OS-9 much!). I used a Disto Super Controller with a 4-in-1 board. IIRC I got the board on sale from Tony at one of the Chicago CoCoFests, the parallel port hardware was bad on it, something I didn't intend to use (I only used the SCSI port, IIRC). It was in a Tandy 2000 case with the 3.5" drive mounted in the very center of the front, had to cut a hole in the case for it. When I stopped using the CoCo much I sold it, around 96 or 97. Figured someone who still used it a lot would get more from it than me sticking it in a closet. Wonder what happened to it? I also had a portable mounted in an old Kaypro case with an amber composite monitor I swapped in for the old IBM style monitor. No HD, but I think I had a 3.5" drive in it along with a pair of DS 5.25"... can't recall for sure if it had the 3.5" though. I know I didn't have a HD, had to use a shorty floppy controller. Wonder what happened to those? Unique enough that if someone on here were using them they would know...
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