[Coco] Where to get CoCo parts -- floppy drive, etc.

Steven Hirsch snhirsch at gmail.com
Wed Mar 2 11:19:52 EST 2011

On Wed, 2 Mar 2011, Steve Bjork wrote:

> For the past six months, I've been working on a hybrid hardware emulation of 
> the CoCo floppy drive system.  Rather than trying to patch the software to 
> get SD cards to work with the CoCo, the idea is to make a device thinks it's 
> a Western Digital floppy disk controller and talks to the CoCo the way 
> software wants to.
> The current design uses two cheap micro controllers.  (Under $9 for both.) 
> The first chip talk to the CoCo by responding as if it's a WD controller and 
> handles all the signal lines to the CoCo.  The second talks to both the SD 
> card and PC for the data needed for the first chip.  I'm using USB as the 
> interface to the PC but that may change to Ethernet in the final design.
> You will be able to setup different configurations of "Floppies" and select 
> between them via a "POKE"
> In addition to the default WD floppy disk mode, the device will also have 
> direct communication mode to even faster speed transfers with extra 
> capabilities.  Playing sound files stored on the SD is one idea being looked 
> into. (Remember, there is a "Sound In" line on the cartridge connector.)

Yes, this is the best approach for the sake of portability.  I've been 
toying with something similar for fitting new storage media to systems 
that require older MFM/RLL hard disks.  These are getting difficult to 
find and are unreliable by current standards.  It should be equally 
straightforward to come up with a daughterboard that plugs into the HDC 
controller socket (usually a WDC 1010 or 2010 on classic systems) and 
picks up a few additional signals (e.g. head select) from the system board 
using micro-clips.  By emulating the WDC register file, the same trick 
could apply.

Great project!

> As for many, the Recession has hit hard and time is very limited.  (I can 
> only spend a few hours a month on the project.)  So please, don't look for 
> this project anytime soon.

No problem.  I think we're all in the same boat.



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