5 Dec
2015
5 Dec
'15
4:18 p.m.
-----Original Message-----
From: cctalk [mailto:cctalk-bounces at classiccmp.org] On Behalf Of Jon Elson
Sent: 05 December 2015 23:40
To: General at classiccmp.org; Discussion at classiccmp.org:On-Topic and Off-
Topic Posts
Subject: Re: Memory Voltage on MicroVAX II
On 12/05/2015 01:49 PM, Robert Jarratt wrote:
first
As the 5V seems fine, the ripple seemed to be
about 20mV (although I
am going to check again), I do wonder what could be causing the memory
modules to appear to be failing. I am hoping that re-seating will cure
it. Regards Rob
I ran a uVAX-II for 21 years here in my house. It was HOT STUFF
when I got it in 1986! By 2007, it was the slowest computer
in the house. It
ran
continuously during that period (at the end, it was
only running a home
environmental monitoring program, or I would have shut it down earlier.)
Anyway, after some years of flawless operation, I started getting crashes
every couple months. When it would hang, I would power down and re-seat
all the boards. It seems like it was usually a failure of one of the
grant chains
(either interrupt or DMA) and the disk controller
would not be able to
transfer. Every once in a while I'd pull all the boards and vacuum out
the
backplane and gently vacuum off the boards. That sort
of helped, maybe.
The external UVII memory also had ribbon cables across the boards. Rough
handling of these cables can cause intermittents.
Jon
Yes, when I took the board out I noticed that the connector of the ribbon
was not fully inserted, although it seemed solid enough. So when I put it
all back together, I really made sure that the board was fully seated and
the ribbon cable connectors fully pressed home. I'll make doubly sure of
this in future. For anyone else's reference, this led to SCBINT errors from
the console firmware while trying to boot.
Regards
Rob