Silicon Graphics / IRIX 13W3 and Sync on Green (SoG) solutions

I picked up a 13W3 to VGA cable with the DIP switches, and the image in OP is helpful but I'd like to clarify what to do with the switches that show ON and OFF? Does it not matter? In which case I've only got #6 switch set to ON and the other 11 set to OFF.
Can anyone take a photo of their working DIP settings for SGI SOG? Thanks.
 
Edit: With apologies, I no longer wish to have involvement with SGUG or SGI communities in general,
and have also chosen to remove all of my content. Many things have changed since I co-founded, named, and ultimately
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This message will replace all of my previous forum posts because deleting threads that I started would have removed
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Elf said:
Removing the sync pins on the VGA side of a BNC to VGA adapter? I would think the easiest solution on a set of BNC to BNC cables, or a BNC to VGA adapter that has separate BNC cables for H/V sync would just be not to connect the H/V sync to anything if you don't want it.

If it's a BNC to VGA adapter that connects the Green channel to H/V sync internally, then removing the pins might help for some monitors?
Click to expand...
I acquired a SUN BNC to 13w3 cable and want to get it to work on an SGI. The monitor has BNC connectors and is a SGI Monitor. I believe from reading that I can remove Pin 7 and it should work. The LCD panel that I have does not support SOG. So just trying to figure it out before I start popping off pins on the cable.
 
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Edit: With apologies, I no longer wish to have involvement with SGUG or SGI communities in general,
and have also chosen to remove all of my content. Many things have changed since I co-founded, named, and ultimately
then left SGUG. There are many good people around, to whom I apologize for frustrating by removing these things, and
also many petty people that over the years whittled down both the enjoyment as well as sense of obligation I used to
feel to anyone else regarding what was ultimately just a hobby. Unfortunately one of the latter now writes the rules
and so it is time for me to take my things and go.

This message will replace all of my previous forum posts because deleting threads that I started would have removed
other peoples' posts.
 
Last edited:
Elf said:
Oh, I see! BNC to 13W3, but Sun configuration. I apologize, I am not sure what would work in that situation, or what would be different between Sun and SGI cables.
Click to expand...
It requires some surgery..

wiki.preterhuman.net

13w3 to VGA

DB13W3 (also known simply as 13W3) is a particular style of D-subminiature connector commonly used as an analog video interface connector that was used primarily on Sun Microsystems, Silicon Graphics and IBM System p computer workstations, as well as some displays from Apple Computer, NeXT...
wiki.preterhuman.net wiki.preterhuman.net
 
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My Indy (8 bit graphics) is paired up with an older NEC LCD display that does not support sync on green. To get around this I wired up the H and V sync pins from the 13W3 connector to the VGA connector. Now the monitor syncs up, but it has a green tint. The reason for this is that the sync signal is added to the green video signal by default, and this shifts the entire video signal up from ground by a few hundred mV. That confuses my monitor into thinking that green video is always on at ~50% level, resulting in the green tint. The sync signal is added to green by the RAMDAC chip, in this case BT445. There is a pin on that chip called SYNC# and according to the datasheet, tying that pin to GND would disable the sync and restore the green video level back to normal. (One would have to lift the pin on the BT445 and carefully solder it to GND to make this work.) Now if there is a way to do this in software or with some ENV command that would be cool, but at some point I'll look into doing this hardware mod to get rid of the sync on green.
 
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Here is the relevant part of the Brooktree BT445 RAMDAC datasheet. When SOG is enabled the green video signal is shifted up ~300mV relative to red and blue. Interestingly this RAMDAC device has a few internal registers and command register 1 bit 7 controls the SOG feature. So maybe a hardware mod is not necessary... that is if SGI provides a way to access these internal RAMDAC registers. Otherwise the hardware mod is to lift pin 147 (SYNC#) on the BT445 and tie it to GND to eliminate SOG.
 

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Edit: With apologies, I no longer wish to have involvement with SGUG or SGI communities in general,
and have also chosen to remove all of my content. Many things have changed since I co-founded, named, and ultimately
then left SGUG. There are many good people around, to whom I apologize for frustrating by removing these things, and
also many petty people that over the years whittled down both the enjoyment as well as sense of obligation I used to
feel to anyone else regarding what was ultimately just a hobby. Unfortunately one of the latter now writes the rules
and so it is time for me to take my things and go.

This message will replace all of my previous forum posts because deleting threads that I started would have removed
other peoples' posts.
 
Last edited:
Jamieson said:
Here is the relevant part of the Brooktree BT445 RAMDAC datasheet. When SOG is enabled the green video signal is shifted up ~300mV relative to red and blue. Interestingly this RAMDAC device has a few internal registers and command register 1 bit 7 controls the SOG feature. So maybe a hardware mod is not necessary... that is if SGI provides a way to access these internal RAMDAC registers. Otherwise the hardware mod is to lift pin 147 (SYNC#) on the BT445 and tie it to GND to eliminate SOG.
Click to expand...

That should be easy to solve. You can tell the Indy to output H+V sync and disable SoG. See my post #4 in this thread!
 
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There was a prom variable crt_option=1 that worked on O2 for ugly greenish screens but on Octane this variable is not known by prom
 
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