[Coco] J & M Systems floppy controller

[Bruce W. Calkins]

>I have an old CoCo floppy controller

>
> I just looked at it again and the EPROM socket is empty

And should already be mapped to &H C000.



> It's a 24-pin ROM socket so obviously it can't use a 28-pin 2764 (8k) 
> EPROM, but it should be able to use a 2732 (4K) EPROM, correct?  I'm just 
> not sure why a 24-pin 8K ROM wouldn't be pin for pin compatible with some 
> EPROM of the same capacity.  Didn't someone mention such an EPROM 
> recently?

And is probably for the Motorola masked ROM, PROM, or EPROM and not pin for 
pin compatible with the more common 24 pin 27XX line.  I suggest some time 
crawling over the spec-sheets.


> Also, what card edge fingers can I cut away?

I would not cut any fingers away.  I would look for a spot where I could 
simply cut traces to isolate what I need to isolate.  Then when I get the 
wrong one I can simply solder a bridge to restore it.


> Thanks for any info.
> Roger Taylor



That is my thinking anyway.

Bruce W.