Pismo Pushing Pixels (or: Matrox DualHead2Go fun)

[Amethyst1]

A PowerBook G3 FireWire ("Pismo") running a 23in acrylic ACD in a dual-monitor configuration. But.... how?!

Must be something to do with that black box: VGA goes in, DVI goes out.

1920×1200 at 65,536 colours with the Pismo in clamshell mode. When using both screens, I get 1024×768 at 65,536 colours on the Pismo's LCD and 1920×1200 at 256 colours on the ACD, but that looks pretty bad. The image quality is "surprisingly" good (better than I expected) although not as clear as when running from a genuine DVI output.
The box can drive two DVI screens off a single VGA output to create a multi-monitor setup; this is the intended use and what I'll try next.
Disclaimer: This is not meant as an ad; I'm just thrilled that this works so well right now.

 

[MysticCow]

You're making me want a Pismo! Actually, I've been wanting one because they seem to hold well and have enough power to be a portable workstation.

 

[Amethyst1]

You're making me want a Pismo! Actually, I've been wanting one because they seem to hold well and have enough power to be a portable workstation.

My 400 MHz Pismo is actually seeing more use than my 500 MHz TiBook, although that may have to do with the fact that the latter's trackpad isn't working...

 

[eyoungren]

You're making me want a Pismo! Actually, I've been wanting one because they seem to hold well and have enough power to be a portable workstation.

For me, it's actually making me want a Matrox DualHead2Go.

 

[Amethyst1]

For me, it's actually making me want a Matrox DualHead2Go.

These boxes come up somewhat regularly at least on the German eBay, with the DualHead2Go variants usually not selling for much (I paid the equivalent of US$23 for a NIB one). There's also a TripleHead2Go allowing three screens to be driven via a single dual-link DVI or DisplayPort, but that tends to sell for a lot more.

 

[Amethyst1]

Update #1: I replaced the last picture in the first post with a screenshot so it's easier to read. Interestingly, I get 65,536 colours instead of 32,768 today (on the Pismo in a dual-head config and on the ACD in clamshell mode). The 32K setting has also vanished from Display Preferences.

Update #2: Another cold boot and it's back to 32K. Weird.

 

[mode11]

For me, it's actually making me want a Matrox DualHead2Go.

Do it! I'm sure you can squeeze a few more monitors onto your desk.

Cool to see this running though. As an alternative, you can get VGA to HDMI adapters very cheaply, which could do the same thing when paired with a passive HDMI > DVI adapter. Sure the Matrox can drive more screens, but the Pismo is already struggling due to its minuscule VRAM. May try hooking up my Pismo to a 22" ACD (1600x1024, so may be easier to drive).

 

[weckart]

Looks pretty good considering it has to share the onboard Rage card. I have a Village Tronic VTBook card, which adds a 32M CyberBlade XP2 card over Carbus. This can output full HD but is a little laggy at that resolution on my Pismo despite the dedicated VRAM.



These seem to come up on eBay quite often and are about the same price as the Matrox. I think subsequent VT cards were better specced but I am not sure whether they would work with the Pismo.

 

[Amethyst1]

Do it! I'm sure you can squeeze a few more monitors onto your desk.

The following is a thought experiment: a G5 stuffed with 4 GeForce 6600s would have 4 dual-link DVIs and 4 single-link DVIs. Hook up a Matrox box to each of the DLs, each outputting 3840×1200 to two 23in ACDs (acrylic or aluminum, pick your choice) for a total of 8 ACDs. Then, hook up 4 additional 23in ACDs to the SL-DVIs Bingo, 12 ACDs run off one G5

Cool to see this running though. As an alternative, you can get VGA to HDMI adapters very cheaply, which could do the same thing when paired with a passive HDMI > DVI adapter. Sure the Matrox can drive more screens, but the Pismo is already struggling due to its minuscule VRAM. May try hooking up my Pismo to a 22" ACD (1600x1024, so may be easier to drive).

If it's just for the VGA-to-DVI conversion, yes (but get one that doesn't top out at 1920×1080 if you have a 23in). For me, the Matrox' dual-monitor capability is the selling point. The Pismo is definitely struggling but it's fun to see how far it can be pushed.
[doublepost=1549059103][/doublepost]

Looks pretty good considering it has to share the onboard Rage card. I have a Village Tronic VTBook card, which adds a 32M CyberBlade XP2 card over Carbus. This can output full HD but is a little laggy at that resolution on my Pismo despite the dedicated VRAM.

View attachment 819419

These seem to come up on eBay quite often and are about the same price as the Matrox. I think subsequent VT cards were better specced but I am not sure whether they would work with the Pismo.

Thanks for bringing up the VTBook. Could the lags be due to the Cardbus interface not providing enough bandwidth (it's PCI isn't it)? Native DVI is a big plus compared to my solution, but there are no drivers for OS 9, right?

 

[Amethyst1]

Another couple of updates...

I tried the DualHead2Go with a single 23in ACD on an original 12in PowerBook (32MB GeForce4 MX) and it has no problems driving the ACD at full resolution in addition to the internal LCD in Mac OS X. Booting into Mac OS 9.2.2 (installed from the MacOS9Lives ISO) results in both screens going black, however.

I then connected a second 23in ACD but it won't do anything with the box hooked up to the 12in PB. I don't have the Mini DVI to VGA adapter so can't test this with a newer 12in PB at this moment.

Moving to an early 2005 15in PB with a 64MB Mobility Radeon 9700 makes the combined 3840×1200 resolution appear (the box presents the two screens connected to it as a single wide one to the host) but with a refresh rate of 57 Hz; selecting that mode causes the LEDs on the two ACDs to blink with the screens staying black. Additionally, the DualHead2Go's LED alternates between green (“OK”) and red (“unsupported mode”).

More testing to follow.

 

[weckart]

Thanks for bringing up the VTBook. Could the lags be due to the Cardbus interface not providing enough bandwidth (it's PCI isn't it)? Native DVI is a big plus compared to my solution, but there are no drivers for OS 9, right?

Yes, I think there were limits to Cardbus at the time but it was still cool to get an external monitor running without taxing the Rage card any more than it already was. It's also a matter of managing expectations. I think we are spoilt by current hardware and what it can do and forget that laptops back then really were cut down versions of desktops.

Drivers were hosted here. I think the links still work. Good for MacOS9 right through to Leopard.

https://web.archive.org/web/20090330012656/http://www.villagetronic.com/vtbook/download.html

Also, this looks interesting. Not sure the Pismo wouldn't start to groan under the strain, though

https://web.archive.org/web/20090322135722/http://www.villagetronic.com/vtbook/dualdisplay.html

 

[Amethyst1]

More progress...

I updated the DualHead2Go's firmware to the latest version just in case.

However, that doesn't change the situation using either an early 2005 15in PowerBook with a 64MB Mobility Radeon 9700 or an early 2005 15in PB with a 128MB 9700, running Tiger. 3840×1200 at 57 Hz across two ACDs doesn't work, neither with the PB's display being active as well nor with the PB in clamshell mode. (I can drive 3840×2160 at 30 Hz via dual-link DVI on the PB with the 128MB 9700 though, even in addition to the internal 1280×854 LCD.)

I managed to confuse Mac OS X enough to display a list of what I presume to be all possible resolutions via VGA, and the highest offered was 2304×1728, so perhaps the 9700 just doesn't want to output 3840×1200 via VGA.

I then tried the setup with a late 2006 17in MacBook Pro with a 256MB Mobility Radeon X1600 running Snow Leopard, and 3840×1200 at 57 Hz works great across two ACDs, even with the internal 1680×1050 LCD running as well I don't get any framebuffer corruption when moving windows across the screens (like I do when driving 3840×2160 from the PowerBook) either.

Again, the image quality is fine to my eyes considering this is two screens driven via VGA.

As a conclusion, 57 Hz is not an issue for the box or the ACDs, it's just the PowerBook's GPU that doesn't want to cooperate.

 

[Amethyst1]

Yes, I think there were limits to Cardbus at the time but it was still cool to get an external monitor running without taxing the Rage card any more than it already was. It's also a matter of managing expectations. I think we are spoilt by current hardware and what it can do and forget that laptops back then really were cut down versions of desktops.

Drivers were hosted here. I think the links still work. Good for MacOS9 right through to Leopard.

https://web.archive.org/web/20090330012656/http://www.villagetronic.com/vtbook/download.html

Also, this looks interesting. Not sure the Pismo wouldn't start to groan under the strain, though

https://web.archive.org/web/20090322135722/http://www.villagetronic.com/vtbook/dualdisplay.html

Thanks for the link to the drivers. I may pick up a VTBook if the price is right to have a play with it. I wonder if you could hook up a DualHead2Go to it and have it output 3840×1200 – if so, that would be a (crazy) way to run two 23in ACDs from a Pismo without putting further strain on the Rage card.

As for that DualDisplay feature, it sounds like it works the same way: presenting a 2560×1024 monitor to the OS and splitting the signal between two 1280×1024 screens.

 

[Amethyst1]

More progress... (Thread title changed to be more accurate— hope that's OK.)

I tried two older 1280×1024 LCDs. But no dice on the 15in PowerBook with the 64MB Radeon 9700. None of the dual-screen resolutions work; they just cause one LCD to flicker wildly and the other to stay black.

However, my 1.33GHz G4 mini with the 32MB Radeon 9200 does a better job

So there you have a G4 Mac mini driving two monitors. I realise the first picture is blurry, but it should be noticeable that the menu bar and Dock run across both monitors since the Mac only sees one virtual monitor. This is slightly annoying but an inherent limitation.

 

[dbdjre0143]

I realise the first picture is blurry, but it should be noticeable that the menu bar and Dock run across both monitors since the Mac only sees one virtual monitor. This is slightly annoying but an inherent limitation.

You could always work around that by moving the dock to a vertical orientation along either the left or right edge. Then it would seem completely normal. Very cool project.

 

[Amethyst1]

You could always work around that by moving the dock to a vertical orientation along either the left or right edge. Then it would seem completely normal.

I usually have my Dock vertical along the left edge. I just left it at the bottom for the picture to illustrate my point.

Very cool project.

To give credit where it's due, I'm not the first to have done it.