[Coco] Disto SC (NOT) needed

[Darren A]

On 11/15/08, Roger Taylor <operator at coco3.com> wrote:
>
> ...
>
> I typed those POKEs and the problem was reproduced.  I tried another
> 64k ECB CoCo 2 and now my "controller" works.  So, I suppose both of
> my CoCo 1's have the NMI line screwed up.  Is there a fix for THAT ?  :)
>

Roger. The problem is almost certainly a blown HALT line inside the
CPU. I've had two such processors which behaved normally except when
disk I/O was performed. In both cases, tests revealed a blown HALT
line. The 6809 seems to be plagued by this problem. Replacing the CPU
will most likely fix the CoCos so they can once again use disks.

Darren