10 Aug
2026
10 Aug
'26
10:16 a.m.
On 8/10/26 12:27, Ethan Dicks via cctalk wrote:
On Sun, Aug 2, 2026 at 8:44 PM Jon Elson via cctalk
<cctalk(a)classiccmp.org> wrote:
Ah HA! This is different than the PC convention! I will
have to make up another cable. Hmm, I wonder if grounding
DTR is responsible for the ?24 UNXINT error during POST?
Thanks,
Jon
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.
There are pinout similarities with a PC DE9 serial port, but AFAIK
it's not intentional.
1: Protective Ground
2: Transmited Data
3: Received Data
4: Request To Send (RTS)
5: Data Terminal Ready (DTR)
6: Data Set Ready (DSR)
7: Signal Ground
8: Shorted to pin 9 on MicroVAX and VAXstation 2000...
9: ...series systems, otherwise left floating.