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From: 123Jim on 16 Mar 2010 04:50

"Paul" <nospam(a)needed.com> wrote in message
news:hnmf35$l38$1(a)news.eternal-september.org...
> 123Jim wrote:
>
>>
>> Turns out there is only one vga connector at the back of the computer (
>> System Model HP Compaq dc7900 Ultra-Slim Desktop)
>>
>> This computer is connected to a splitter (Rextron Video splitter vsa12)
>> the outputs from it are connected to the monitor and to the Smartboard's
>> projector.
>>
>> The problem is the computer does not seem to know there are two video
>> displays, and so there is no option for extended desktop on the Intel
>> graphics controller software.
>>
>> and as I mentioned previously there is no freeze function on this board's
>> projector.
>>
>> What is the solution?
>>
>> cheers
>
> The manual for the VSA12, indicates it is an active buffer device.
> It is a distribution amp, that runs off a 9V wall adapter.
> And what that should do, is make two identical copies of the
> original video signal. If the smartboard and the monitor don't share
> a common resolution, then one of them may indicate "out of range".
>
> http://www.rextron.jp/products/manual_e/REXTRON_VSA248.pdf
>
> Another small detail, is the connection of DDC. There is a serial
> clock and data interface on the VGA cable. Computer monitors have
> a table of resolutions stored in them, which can be read out. That
> is how the computer figures out what resolutions to use (in theory).
> When there are two devices connected, you'd hope that one of the
> ports is the one that has the DDC connected. If you look in the
> Display control panel, maybe you'll see one of the devices named
> by its Plug and Play information. And that would tell you that
> the computer is able to see the serial data on the DDC interface.
> In any case, you'd still have to select a resolution and refresh
> rate they both like.
>
> This program allows you to see whether any Plug and Play is coming
> across or not. It might tell you which device is providing DDC
> info, if any is actually coming across. Not all VGA devices have
> such an interface. For example, a projector might not have DDC
> on it, just the RGBHV signals.
>
> http://www.entechtaiwan.com/util/moninfo.shtm
>
> If you only have the one VGA output on the computer, you can produce
> just the one signal with that. You can feed identical copies to both
> display devices, but you won't have "extended desktop", "clone" or
> any other video driver functions like that to work with.
>
> What you need, is a video card. You mentioned the words "ultra-slim"
> above - eek! That severely limits what you can do with that computer.
>
> And page 1 here, shows the bad news. This is almost a laptop, in terms
> of expansion capabilities.
>
> http://h18000.www1.hp.com/products/quickspecs/13029_div/13029_div.PDF
>
> But don't despair. There is still hope. They make USB2 video display
> devices. You won't be playing 3D games on it, but for mostly static
> display output, it'll be fine. I believe these things use a degree
> of data compression on the USB cable, which helps compensate for the
> 30MB/sec or so you might expect to get on a USB2 cable.
>
> I like the reviews on this site, because they can give some background
> on the device in question. The chip inside this one is made by
> DisplayLink. It is possible an earlier version had a VGA output. This
> one is DVI (and I didn't notice if it said DVI-D or DVI-I).
>
> http://www.newegg.com/Product/ProductReview.aspx?Item=N82E16815101001
>
> There are more examples here. This is the company that makes the chip,
> and this page has some other suggestions of hardware that uses the
> chip.
>
> http://www.displaylink.com/shop/index.php?product=5
>
> Perhaps if you can find something like that, where you are, you
> can set up a second independent video output on your ultra-slim
> that way. Just don't expect to be playing 3D games on it.
>
> Not all the devices of that type, use data compression or incremental
> update techniques, to drive the display. Some of the earlier devices,
> would be relatively dumb, and a bit slower. Also, the output
> resolutions of earlier attempts at this kind of technology, may be
> lacking (like 1024x768). The DisplayLink may be one of the first
> "barely acceptable" solutions, while some of the earlier designs
> are only fit for the nearest garbage dumpster.
>
> There was one LCD computer monitor, that offered a USB connection
> on the monitor for video purposes. It uses a DisplayLink chip
> and one other neat feature it had, was the monitor had a copy
> of the driver stored in flash memory. When you plugged the monitor
> into the computer, an Autorun in the flash memory, would be automatically
> run by the computer, and within a few seconds, you'd have a video
> output on the screen. But that only worked for perhaps one OS,
> and what was stored in flash didn't satisfy all possible OSes.
> Still, it is an example of trying to integrate the function,
> right into a monitor.
>
> http://www.everythingusb.com/samsung_syncmaster_940ux_11970.html
>
> Here, you can see that Samsung monitor has two functions on the
> USB cable. "Ubisync" is the video display interface in the monitor,
> while the other one is the USB Mass Storage (flash) that holds
> the driver code.
>
> http://www.everythingusb.com/images/list/samsung940uxusbdevmgmt.jpg
>
> Once you get something like that set up, that should give you an
> independent display.
>
> *******
>
> There is yet another solution, but it relies on the characteristics
> of the GPU in the computer. Matrox makes a number of different models
> of display splitting devices. For example, imagine the computer had
> the ability to drive 2560x1024 out on the VGA cable. The Matrox device
> splits the output down the center, sending the left half to one VGA
> output (1280x1024) and the right half to a second VGA output (1280x1024).
> It means the two display devices should like the same kind of signal,
> but at least in that case, you have an "extended" desktop of sorts.
>
> +------------------+ +-----------+ +-----------+
> | 2560x1024 | ===> | 1280x1024 | + | 1280x1024 |
> | | | | | |
> +------------------+ +-----------+ +-----------+
>
> You can start checking compatibility here.
>
> http://matrox.com/graphics/en/support/gxm_main/
>
> I think this one might be a (wide) VGA in, to two VGA out.
>
> http://www.newegg.com/Product/ProductReview.aspx?Item=N82E16815106015
>
> This article, shows a picture of what is inside the box.
>
> http://www.anandtech.com/displays/showdoc.aspx?i=2621&p=2
>
> And this article, is for the triple-head version, which
> requires the computer to drive out an even wider signal
> to make it work.
>
> http://www.anandtech.com/printarticle.aspx?i=2806
>
> Have fun,
> Paul


Thanks again Paul ... unfortunately I don't have control over this system
and have to wait on the sys admins to do something .. ( I can only suggest)
it seems unlikely they will go to such lengths to add functionality even
though it's vital for best use of resources.


From: Paul on 16 Mar 2010 07:36
123Jim wrote:

>
>
> Thanks again Paul ... unfortunately I don't have control over this system
> and have to wait on the sys admins to do something .. ( I can only suggest)
> it seems unlikely they will go to such lengths to add functionality even
> though it's vital for best use of resources.
>

Then you'll have to rely on your debating skills :-)

In a conference or meeting room, if a computer is installed, it is
mainly in support of AV (audio/video functions). That means the computer
must have the ability to do a good job of supporting projection and
display devices. The selection of the "ultra slim" computer, while
providing a networked computer, fails to support video properly.
And likely would fail for any other flexible needs, like setting up
a video conference. The ultra-slim did meet the objective of being
"unobtrusive", so it met its furniture objective. But it sounds to me
like it is too small to be worth having.

If you buy a box with the next size up, some of the sins can be corrected
via the low-profile expansion slots. Even so, some low-profile slots are
so short, that no video card can be found to fit in them. In some cases,
even if there were expansion slots, it might be hard to find a good product
to populate the slots.

Paul

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