16 Jul
2006
16 Jul
'06
11:14 p.m.
Pat wrote
You do realize that the "stuff" we talk about
on classiccmp are usually things
that aren't PC's, right?
Yep, that's why I posted here :-) - it's a SGI IRIS 3130 68020-based Multibus
machine.
I'm sorry that I gave the impression it was a PC, I was just trying to not scare off
anyone who hasn't ever worked with one of these beasts but who knows about
computer video/graphics systems. I did pull some numbers from the XF86 PC modeslist
to see if what I was seeing was close to "normal", it didn't seem to be.
Jules wrote
I suppose it's just possible that you could do
interlaced 1024x768 with a
28KHz signal, but it'd be hell on the eyes. Possibly that's the SGI's default
though if it can't detect what monitor you're plugging into it? (scratch that
idea if the outputs are BNC, but if the video's done over some form of
multi-pin connector, might it not need strapping in a certain way to indicate
display type?)
The monitor connection is 4BNC. I wasn't sure about the interlaced - it seemed that
mathematically
it should be 24 KHz (48/2), but if 28KHz could be it, I'll look again.
There's a switch that's supposed to select interlaced/non interlaced. I guess next
stop is to check if
that's being read properly, since flipping it doesn't seem to make a difference.
I'll also try to find the crystal oscillator
(thanks, Tony), perhaps it's on the Update Controller?
I think the interlacing must be for linking it up with a TV system, since the monitor
can't do 30Hz interlaced.
Standard refresh is 60Hz (per the IRIS FAQ)