19 Jun
2020
19 Jun
'20
3:43 p.m.
On Fri, Jun 19, 2020 at 12:24 PM Robert Armstrong via cctech <
cctech at classiccmp.org> wrote:
It appears that my RK8E has a problem - it fails the
diskless control
test
with
.R DHRKAE.DG
SR= 0000
COMMAND REGISTER ERROR
PC:1160 GD:0000 CM:0001
DHRKAE FAILED PC:6726 AC:0000 MQ:7777 FL:0000
WAITING
Ok, maybe a bad bit in the command register so I'll check it out. But then
it dawns on me - how do you work on this thing? It's three boards
connected
with "over the top" connectors - you can't use a module extender on it.
Worse, the M7105 Major Registers board is the middle one of the stack! Is
there some secret to working on this thing? Has anybody fixed one? Any
suggestions?
I did some debugging on mine with two quad-height extenders and one
half-height (used upside down).
In such a way you can raise up two of the boards in back (on the quad
extenders) with the one in front installed normally but with the
half-height extender upside-down and plugged into the top connectors, so
the edge fingers of the extender plug into the top blocks.
Yes, it's ugly, and it only gains you access to half of the board you're
trying to poke at. Building some sort of ribbon cables to substitute in
for the top blocks/upside-down extender would be more, uh, flexible, but I
was fortunate that what I needed to look at was on the unobscured side.
- Josh
I hadn't thought about it before, but the KK8E CPU would have the same
problem. Fingers crossed that one never dies...
Bob