[rescue] SGI monitor info

Joshua Boyd jdboyd at jdboyd.net
Sat Mar 20 13:21:32 CST 2004

On Sat, Mar 20, 2004 at 02:15:36PM -0500, Patrick Finnegan wrote:
> On Saturday 20 March 2004 13:42, Joshua Boyd wrote:
> > On Sat, Mar 20, 2004 at 05:23:17PM +0100, Jochen Kunz wrote:
> > > When the monitor really can't do SOG you have to build a sync
> > > separator with a LM1881.
> There's always the datasheet:
> http://www.national.com/ds/LM/LM1881.pdf
> It looks like you get your vertical sync from pin 3 (aptly named 
> VERTICAL OUTPUT) and your horizontal sync from pin 5 (BURST/BACK 
> PORCH).  Of coures, I've never tried playing with one of these yet, and 
> they seem to be aimed more towards NTSC video separation.

Whoops.  I plugged LM1882 into National's web site, and was thus looking
at the data sheet for a much more bewildering chip.

Anyway, looking at the 1881, I guess the idea is feed the green line
into the composite pin and get the sync out.  But, will this chip run at
high enough rates?  On page 8, they mention normal vertical scan rates
with 60hz to 120hz in parenthesis.  Of course, we aren't just talking
about using a higher scan rate, but a higher resolution as well.

So, any way, yes, we have a data sheet, but it wasn't unreasonable for
me to ask for a pointer to how to do it.

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