SGI: Hardware

I dont know what the trigger was, but, it decided to turn back on.. I think maybe I have a flakey Fuel.. too many strange things happening every time I interact with it.

I am trying to make sure my hardware is working as intended so I was going through the multi monitor configuration.

The V12 Pro w/DCD option, all 3 of the DVI connectors are active and display on my 3 screens. I get a clone being output to each screen.

If I go into display properties, it only allows me to select single resolution or 2@ resolutions to get 2 monitors working.

Does IRIX 6.5.30 w/DCD support all 3 screens active as separate displays so that I can move windows around between the 3 monitors? I was under the assumption that all 3 outputs could be used simultaneously.

According to the manual, the base DVI port and the DVI ports on the DCD are an either/or situation (which along with the bandwidth restrictions of the V12, is why you don't find any factory-provided 3@ display formats). http://techpubs.sgi.com/library/tpl/cgi ... /ch03.html

As a follow up to the previous subject; if you were able to reboot your L1, was there any change in how your graphics board appeared ineither a "serial all" or hinv -vm?

Yes, that is exactly correct.


Why were you under that assumption ? I have never read anything like that anywhere. It's called a dual channel display because it supports two screens !

I was reading that exact section but I didnt see anything in there that said either/or.. or maybe I just glossed over it?

In any case. Thanks for the clarification.

Regarding the other topic, the listing is still the same after reboot but I think its because my POD needs to be flushed.. I had this same problem when I put the 800Mhz CPU in. It took a bit of work to get things cleared up. I need to revisit this as soon as I get some time to tinker with it again. I was distracted with trying to make sure the video card was doing what it was supposed to.

Yes.. I read it as DCD **ADD ON ** card meaning it would ADD a Dual Channel display to the existing SINGLE display. Then, when I saw the 3 DVI connectors I assumed I made the correct assumption, otherwise, why wouldnt they supply a DCD with only 1 extra DVI connector.

Also, why does the screen clone to all 3 DVI connectors when I am in the O/S ? All 3 ports remain active. My hope was that I could tell the Xserver display to activate all 3 as separate monitors instead of cloning.

When I look at the output of "gfxinfo" it does print: Monitor 0, Monitor 1, Monitor 2

I am too polite to say where you could have got these ideas

Here's the actual document describing the Dual Channel Display option (Also note that dual head is a different matter as well) :

http://techpubs.sgi.com/library/tpl/cgi ... lay_Option


It doesn't, obviously. If it did you would get a display on all three screens.

But you don't. Ergo ...





If you look through the documents, all you will ever see anywhere are instructions for connecting two monitors to a dcd.

http://techpubs.sgi.com/library/tpl/cgi ... /ch03.html

http://techpubs.sgi.com/library/tpl/cgi ... /ch04.html


If wishes were horses, beggars would ride.

I appreciate the input, but, are you sure? lol...

Yeah, pretty sure. Going on eight years with this one ...

The specs say the dcd delivers the "top of the frame buffer" to channel 0, the "bottom of the frame buffer" to channel 1. Not sure what that means but what you get from the not-to-be-used, blocked-off original connector is a sort of undependable, alternating flashing mess.

Your picture doesn't show up here. It's easy to upload to nekochan so that the information is not lost in future. Look below, you'll see "browse" and "add the file" buttons. They work in both Irix Fireflop2 and Fireflop3.

Mr Recondas who has also posted to this thread is possibly the only person outside SGI who has ever been able to make the 2@ vfo files work. Best to listen when he speaks.

My take on this: Because they originally designed the DCD for use use with Octane VPro cards, which just had a single 13w3 output. Later I guess it was easier to use the existing DCD as-is rather than design a new option card specifically for the Fuel.

I think it's more complex than that, sm. The DCD is doing some strange stuff. It appears to be doing something similar to the stereo display thing - one apparent graphics stream is actually two alternating streams, and the dcd is splitting them. If you do try to use the original un-split stream, you get two alternating displays on the same monitor. I have never seen a good technical explanation of exactly what is going on.

Perhaps they didn't want anyone to know ...

Considering the other issues you seem to be having with your Fuel I'm sort of surprised you'd channel your peer support into a lengthy discussion on a question that for all intensive purposes has already been answered.

The 2@ display formats SGI provides for use with DCD equipped V12s provide a little more insight into hamei's references from TechPubs: 2@ DCD formats are built from two display fields, each of which has half refresh rate and the resolution of the original target display image, with the result being a single logical image that spans monitors connected to both of the DVI ports on the DCD. The base DVI port still receives the original signal, but because the DCD is hardwired to split that very same image into matching left and right halves, the base image and spanned logical image will always be the same. You probably aren't seeing the limitations the DCD imposes on the base DVI port because you haven't loaded one of the DCD-intended 2@ formats.

Once you load one of the 2@ formats intended for use with the DCD, you'll likely discover that the alternating half-field/half-refresh rate images formatted for display across a two monitors aren't very pleasing to the eye if viewed on a single monitor connected to the base display port - especially if the connected monitor is a CRT (an LCD panel probably won't sync to the half-refresh-rate display signal). The DCD is SGI's end-run around the size limitations imposed by the design of the both the Octane and Fuel/IP35 versions of the V12. In the case of your Fuel's V12 the base display port is single link DVI. The single link DVI standard calls for a maximum pixel clock frequency of 165 MHz , which is why SGI doesn't provide (non-DCD) V12 display formats larger than 1920x1200@60Hz (and the limitations on the pixel clock on the Octane/13W3 V12 are pretty much the same).

The DCD is able to provide for a larger logical image by splitting the image into two smaller halves, each with a lower refresh rate. That's also why there are two DVI connectors on the DCD - the logic on the DCD PCB intercepts the display signal directed to the base DVI port, and sends half to each of the ports on the DCD.

Ahh, now that the photo is there I can see what he's talking about. Yes, I guess if you want three monitors that all have the same display, you could do that . There is probably a use for that but not what it was intended for.

As soon as you go to a 2@ format, they start to alternate.

Psychedelic, man

Thanks for all the details and input guys! I truly appreciate it. Wealth of knowledge on this site.

When I saw the 3 connectors on the V12 DCD I made some assumptions that I could have all 3 of my displays running as an extended desktop.

For what it's worth, if I switch the mode to 2@, I get 1 monitor that just stays black and the other 2 become active. I wanted to go through this excercise because I wanted to make sure my hardware that I paid for was at least doing what it was supposed to. Now I will revert my attention back to getting to the bottom of the incorrect part # showing up for my V12.

I will do a clearalllogs, initalllogs, flush and reset like i did with the CPU upgrade and see if that clears it.

Apparently, there's no magic going on in there, otherwise Discreet would not have been able to offer an external DVI splitter (a not SGI specific product made by Gefen) as an alternative to the DCDs, nad apparently, there are even cheaper alternatives, like the one offered here viewtopic.php?f=4&t=16727045

I have no Idea what kind of video timing one has to use to get 2 separate displays with one of those splitters, or if the 2@ timings are selectable.

Please don't do that, it's "for all intents and purposes".

Well, if you configure the DCD to duplicate a single screen across both DVI connectors, then you can functionally replace it with a DVI splitter (such as the one sold by Gefen)

But if you configure the DCD to two independent screens (the 2@ modes), then I don't see how you can replace it with a splitter.

I think you've just proven that Discreet setups don't use 2@ modes Somebody with a working setup should be able to figure this out ...

As jan-jaap has already mentioned, it looks like the DCD offers a least a little more magic than the Gefen or Connspot units. The recommended-by-Discreet Gefen DVI splitter unit got mentioned in a thread a few years back and the question came up as to whether the Gefen unit could directly replace a DCD. Discreet mentions the specific Gefen unit by name in their Tezro set up manual: To satisfy my own curiosity I contacted Gefen and was advised the HDTV Splitter Distribution Amplifier split a single DVI signal into two identical (mirrored) copies. I haven't contacted Connspot, but a web search gave a pretty strong impression it was a lower cost functional clone of the Gefen unit.

Sorry for the malapropism. Sometimes it's hard to teach an old dog new tricks, but I'll see if I can't do better next time.