12 Aug
2026
12 Aug
'26
8:56 a.m.
On Tue, Aug 11, 2026 at 8:26 PM Jon Elson via cctalk
<cctalk(a)classiccmp.org> wrote:
On 8/10/26 12:27, Ethan Dicks via cctalk wrote:
Excellent.
On Sun, Aug 2, 2026 at 8:44 PM Jon Elson via
cctalk
<cctalk(a)classiccmp.org> wrote:
Thanks, Ethan for the reminder! Fixing the cable makes
things work a bit better... The ground was the problem. For some CRAZY
reason, pin 5 of
the 9-pin serial connector of the KA630-AA and cabinet kit
has a 1K Ohm resistance to system ground.
I don't doubt that you had a problem
with ground, but on a MicroVAX
console port, Pin 5 is not ground. Ground is Pin 7.
5: Data Terminal Ready (DTR)
7: Signal Ground
...but I still have the ?24 UNXINT
error. I also get some garble when I first start it up. I
doubt the uVAX is doing and auto-baud, as it has the rotary
switch, so maybe the USB-serial adapter is trying to
outsmart the settings given to minicom.
Not sure about your baud barf. Yes, the uVAX won't be sending at any
other speed than the one it's set to.
But, I can't seem
to get around the UNXINT error. It may be a bad KS630 board.
I looked over the KA630 manual and it lists 24 UNXINT but doesn't go
into specific situations, just an unexpected interrupt.
Ultimately, it's an interrupt coming from some source that's not
expected (as the language of the error text would suggest). That can
be a defective CPU board, can be a defective peripheral, a
misconfigured peripheral, or in some very rare cases a backplane or
extender card problem that affects bus lines.
If you don't have a spare CPU (or a second system box), I'd list out
what devices are on the bus and see if you can pare any down. Not all
Qbus devices have the vector set by DIP switch, so for those, it's all
soft configuration. If you have devices that have a Vector DIP
switch, check the settings and honestly, check the switches
themselves. I have seen DIP switches fail with age (especially if
there's graphite in there because someone used a pencil in the past).
Back in the day, we'd also run the "CRD" (Customer Runnable
Diagnostic) which isn't as extensive as old MAINDECs or XXDP but
should hit the high points with the CSR and vectors and a few local
hardware tests. We used to boot our CRD off of TK50 which is its own
perilous journey these days.
If you can reduce the machine to CPU, RAM, and your boot device, that
would simplify testing.
-ethan