Subject: Re: DecStation 5000/120 Troubles...
To: James Alexander Jacocks <>
From: Michael L. Hitch <>
List: port-pmax
Date: 02/20/1998 15:06:55
On Feb  1, 11:53am, James Alexander Jacocks wrote:
> I have a DECStation 5000/120 32/1gb with CDROM.  I have a PMAGB-BA
> framebuffer.  As I have come to understand it, the PMAGB-BA that I have
> actually has the second oscillator that would normally be installed on a
> PMAGB-BC.  Whenever I try to boot any version of NetBSD, the display goes
> haywire.  (I.e. everything goes interlaced and moves slowly off the
> screen)  I can read (sortof) the output enough to see that NetBSD is
> actully booting, so the system doesn't crash.  However, it is _extremely_
> difficult to use without the console. :)
> I haven't tried the 1.3_release kernel, but I tried 1.2g and all the beta
> kernels, and so for, no luck.  Any ideas?

  I had a chance this week to play with a PMAGB-BA that has two crystal
oscillators.  I was trying to get it to work with a 17" monitor I have
at home.  With the jumper removed, the board uses the higher frequency
oscillator, and gives a display of 1280x1024 - which didn't work with
my monitor.  On a whim, I added the jumper which appears to use the second
oscillator, and that resulted in a 1024x786 display which worked with my
monitor - until NetBSD booted anyway.  NetBSD assumes that the PMAGB board
is 1280x1024, which will not work correctly when the PMAGB is using the
slower oscillator.

  I modified the sfb.c driver to use 1024x768 and was able to get NetBSD
to boot using that resolution.  The trick now is to have the driver detect
what resolution the PMAGB is actually using and automatically set the
appropriate display parameters.  From the sfbreg.h file, I do see a couple
of registers on the PMAGB that seem to have something to do with the
horizontal and vertical configuration, but I don't know what the values
of those registers really mean.


Michael L. Hitch
Computer Consultant
Information Technology Center
Montana State University	Bozeman, MT	USA