[Coco] OS9 vs Flex

[Darren A]

On Sat, Dec 31, 2011 at 5:25 PM, John Kent wrote:
> ....
>
> Has anyone interfaced high density 3.5" floppies to the CoCo ? Because you'd
> be up for the same problem with those. The data rate would be too fast for a
> 6809 software polling loop for the 1.44MB floppies. You'd need a floppy disk
> controller with sector buffering for the CoCo.
>

The CoCo floppy controllers tie the WD17x3 DRQ line to the CPU's HALT
input.  This makes it possible to do high density disk I/O on the CoCo
at the normal 0.89 MHz speed (without polling).  I have done this
using a modified 26-3029 controller.

Darren