Junkbox CP/M system?

Chuck Guzis cclist at sydex.com
Tue Apr 24 13:07:20 CDT 2007

On 24 Apr 2007 at 10:12, Allison wrote:

> At a minimum.  FDC interfaces are more involved as the interface has to 
> include data and drive interfaces unless one can find a chip like 2793
> or 37C65.

My personal favorite is the WD1770/1772 series.  It doesn't do 
500Kbps drives (no big deal for CP/M); interface logic is very 
minimal.  Very simple to program; a 4MHz Z80 should be able to keep 
up with the data transfer without breaking a sweat. And it fits in a 
reasonably small (28 pin) DIP package.

But a minimal system might incorporate nothing more than a PIIO or 
SIO and simply pass mass-storage requests and console I/O over the 
same path to a PC using a formatted message scheme.   Makes the CBIOS 
coding a walk in the park.

Or, one could build the Z80 onto a PC prototype board with its own 
local memory as a coprocessor and conduct mass storage and console 
I/O over a pair of I/O ports.  For many, that may be the best of all 
worlds as it relieves one of the problem of terminal and disk 
interfacing, power supply and enclosure.  Of course, the folks who 
want to put their project into a mahogany case with glass front may 
not be taken with this idea. :)


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