[Coco] Checking/Testing a 68B09P

[Mike Pepe]

jdaggett at gate.net wrote:

> Pins 33 through 39 are different between the MC/HD68B09 and the 
> MC/HD68B09E. The differences are significant that would require major rewireing 
> of the COco motherboards to use a MC/HD68B09. 

Er... what?

No amount of rewiring will get a 68x09 to run in a CoCo. Rigging up some 
sort of contraption to get the clocks synchronized may be possible, but 
I wouldn't recommend it!

> 
> Yes you could build a breadboard with a simple program in a ROM and test the 
> parts. You  cou ld even build a breadboard to plug into a COco to test the parts. I 
> would recommend a Coco 1 or a Coco2 that  has the MC68B09E socketed. On 
> the breadboard you would need to have a crystal that is 4 times the .89MHz clock 
> speed. That would wire to pins 38 and 39. Those pins on the breadboard would 
> not wire to the socket on the Coco. Also pins 33, 34, 35 and 36 would not wire to 
> the socket of the Coco. The rest are the same. 
> 
> james

Not sure what you're envisioning here either, but, again, without being 
correctly synchronized to the SAM, you'd have problems.

The best way to test these would be to yes, rig up some sort of 
perfboard/PCB with a ROM and some sort of I/O to run a program and 
indicate that there's a good result. It wouldn't be terribly difficult 
to wire-wrap up something to accomplish that.