Simulate a VGA monitor connected to a computer?

[notme]

Apparently different video drivers are loaded depending on if a monitor is
connected or not. This is the case when connecting via VNC to a "headless"
Mac Mini.

Using just a Mini-DVI-to-VGA adapter won't load another driver.

Is there a way to emulate a monitor connection?

Is this a case of I^2C communication? Any simpler method?

Thanks.
N.

 

[Tim Williams]

Is this a case of I^2C communication? Any simpler method?

I think so. I can't get VGA from my laptop without I2C... when I try
forcing it, Windows drops the data line (request, I suppose) for about 1ms,
then it fails, not detecting anything. And I so wanted to get raw RGB+sync
signals at the time... guess I won't be doing that, at least without
something I2C on the line (EEPROM? uC?).

Tim

 

[IanM]

I think so. I can't get VGA from my laptop without I2C... when I try
forcing it, Windows drops the data line (request, I suppose) for about 1ms,
then it fails, not detecting anything. And I so wanted to get raw RGB+sync
signals at the time... guess I won't be doing that, at least without
something I2C on the line (EEPROM? uC?).

Tim

Its a *long* time since I was digging around inside monitors but IIRC to
fake one you'll need a 24C02 I2C EEPROM programmed with suitable VESA
EDID data *AND* 75 ohm resistors to ground on the R B and G lines.
Probably easiest to rob a dead CRT monitor for the EEPROM if this is a
one off project. Otherwise you'll need to research VESA DDC2B and EDID.

 

[notme]

What problem are you trying to solve?

When VNC'ing into a Mac Mini (Mini has 10.5.7), I cannot see data in Apple
Numbers spreadsheets. They appear blank (all menus work, all features of the
spreadsheet function -- there's just no data displayed). The spreadsheet
prints and shows the data OK.

The author of the VNC client tells me that it's probably because of the
default display driver. He suggests plugging in a monitor or emulating one. I
am moving house and have nothing (my monitors and most everything else is
2000 miles away) other than the Mini and an old PowerBook G3/400 (w/ 10.4.11)
that I'm using for the VNC client.

I tried another "brand" of VNC client with the same results.

I tried changing numbers of colors and display resolution with no results.

not

 

[notme]

followed by a DVI Detective might do it.

<http://www.gefen.com/kvm/dproduct.jsp?prod_id=4714>

Yow! $80. Hmm...

Well, if I can't find a simpler way, I'll look into this.

Thanks.

Dave

 

[Doc O'Leary]

Yow! $80. Hmm...

Well, if I can't find a simpler way, I'll look into this.

The DVI-to-Video adaptor is only $20, and I'm guessing it doesn't need
to query a TV to provide the composite signal.

 

[notme]

The DVI-to-Video adaptor is only $20, and I'm guessing it doesn't need
to query a TV to provide the composite signal.

Good idea. Any favorite makes / models?

Thanks.

 

[notme]

Have you tried opening the spreadsheet in a brand-new Mac OS X user

account to see if the problem is local to that user account?

Spreadsheet appears identical regardless what user opens it on this Mini via
VNC.

Have you tried placing the spreadsheet on another computer that you can
access remotely with VNC to see if perhaps the problem is local to the
Mac mini?

No other computers available. I'm moving house and all my tools & stuff is
2000 miles away.

I would be extremely interested in seeing a screen shot so that I know
exactly what you are describing is what I imagine from your description.

<http://i29.tinypic.com/2ebcric.jpg>

I can access all menus and buttons on the window. Note the term "Rent" in the
edit field just below the Format Bar. This shows the content of the current
cell, and changes as I use the arrow keys to scroll around the (invisible)
cells of the spreadsheet, so I know the data exists.

Printing works as it should and shows a normal spreadsheet populated with
data.

Thanks.

 

[Chris Ridd]

Spreadsheet appears identical regardless what user opens it on this Mini via
VNC.


No other computers available. I'm moving house and all my tools & stuff is
2000 miles away.


<http://i29.tinypic.com/2ebcric.jpg>

I can access all menus and buttons on the window. Note the term "Rent" in the
edit field just below the Format Bar. This shows the content of the current
cell, and changes as I use the arrow keys to scroll around the (invisible)
cells of the spreadsheet, so I know the data exists.

Printing works as it should and shows a normal spreadsheet populated with
data.

That's a pretty interesting way for Numbers to fail, and I'm wondering
if it is using Quartz in some way that VNC isn't supporting.

Which VNC server and client are you using? Have you tried different
clients? (Not sure if you can run a different VNC server...)

If you've got Xcode installed, can you run
/Developer/Applications/Graphics Tools/Quartz Debug.app and play with
the Disable Quartz Extreme/Enable QuartzGL menu items? I think you need
to restart Numbers after making these changes.

 

[Doc O'Leary]

Good idea. Any favorite makes / models?

I was just talking about what the Apple Store has available. You could
probably find cheaper at any computer shop, especially if you're not
really going to use it.

 

[notme]

I was just talking about what the Apple Store has available. You could
probably find cheaper at any computer shop, especially if you're not
really going to use it.

You mean? ::

<http://tinyurl.com/kmqcbu>

 

[notme]

Have you tried doing this yet?:

<http://soerennielsen.dk/mod/VGAdummy/index_en.php>

Thanks for the creative suggestion.

I just made up one tonight and plugged it into the Mini. It had an effect, if
not the one I expected.

When I plug in the "dummy" connector and reboot, I cannot connect to the Mini
via VNC at all. (Tried different clients; no joy.)

If I unplug the dummy, the mini behaves as before; VNC connectivity is
restored.

???

Thanks.

 

[IanM]

Thanks for the creative suggestion.

I just made up one tonight and plugged it into the Mini. It had an effect, if
not the one I expected.

When I plug in the "dummy" connector and reboot, I cannot connect to the Mini
via VNC at all. (Tried different clients; no joy.)

If I unplug the dummy, the mini behaves as before; VNC connectivity is
restored.

???

Thanks.

Sounds like its getting stuck before the VNC server starts. Probably
because its got a dialog box up resulting from the monitor change. Can
you set the resolution to 640x480 via VNC and try again?


As all ID pins open was originally defined as 'no monitor', it would
also be worth connecting pin 11 (ID0) to pin 5 (GND) to properly
identify your connector as a colour VGA monitor.

I don't think grounding pin 4 (ID2) will help as I doubt the Mac
supports IBM 8514/A displays It is worth a try though if you
already have it working at 640x480 to see if you can then switch to
1024x768.

You *will* need the I2C eeprom if you want to emulate a higher
resolution monitor.