[Coco] high density floppy controller mods

[Mark Marlette]

Mike,

Is this the mod that Robert Brose of our Twin Cities Color Computer 
Group designed over ten years ago??? Or are you doing your own? 
Robert's mod is up on RTSI.

I have been running the HD modified 3029 controller and it does work 
under NitrOS-9 with the proper descriptors. PCDOS even works and that 
is my transfer method to/from the PC.

I added a line on the interface cable to send the density hole to 
automatic place the controller in the right clock speed based upon the 
sensor's output.

Mark

Quoting Mike Pepe <lamune at doki-doki.net>:

> Hi folks,
>
> I'm about half way through my hacking on a 26-3029 disk controller to 
> make it function with both high and low density 3.5" disks.
>
> I've split out the chip select signals and I have an additional 6-bit 
> register at $FF41 that I intend to use to switch between high and low 
> density mode. Actually only one bit is needed to do this, but wiring 
> up the other 5 was trivial. (not sure what I'm going to do with those 
> bits-  if anything- at this point)
>
> I'd like to do something to make this mod portable and maybe a 
> "standard" mod, especially for nitros9 where this sort of mod is 
> actually useful. (assuming it works, of course)
>
> I don't see anything wrong with using $FF41 as a secondary control 
> register, but if anyone can think of a reason why it might not be a 
> good idea, let me know.
>
> Also I'm working on making a read register so it would be possible to 
> query the drive's density select line, just to make sure that the 
> inserted disk and the controller mode agree. It would probably be 
> nice to also be able to read the status of the disk change bit too.
>
> Assuming this works I'll post the mods to a web page so everyone can 
> make their own.
>
> -Mike
>
>
> -- 
> Coco mailing list
> Coco at maltedmedia.com
> http://five.pairlist.net/mailman/listinfo/coco
>