Aero video-specifications - the 256 color problem and much more

The Aero 4/25m has a SPC8108F0c, the 4/33c a SPC8106F0b video chip from SMOS.
Here is a picture from the SPC8106F0b in my Aero (10kB).

Is it able to do 256 colors in 640x480, in Windows?

Well, with programs like the Quick Picture Viewer or Cshow you can already use the following 256 color modes to display graphics:
320 x 200, 320 x 400 and 360 x 480.
David Murray (dmurray@powermedia.net) found out that you can get lots of other video modes on an external monitor, using the program fractint. These modes are the following IBM (std. / non std.) VGA/EGA/CGA modes:

colors	resolution	V sync. [kHz]	H sync. [Hz]
2	640 x 200	31,8	70
	640 x 350	31,5	70
	640 x 480	31,5	60
4	320 x 200	31,8	70
16	320 x 200	31,8	70
	640 x 200	31,8	70
	640 x 350	31,5	70
	640 x 480 (aero std.)	31,5	60
	704 x 528	33,0	56
	720 x 540	32,4	55
	736 x 552	31,8	52
	752 x 564	31,2	51
	768 x 576	30,6	49
	784 x 588	30,0	47
	800 x 600	29,6	45
256	320 x 200	31,8	70
	320 x 240	31,5	60
	320 x 400	31,8	70
	320 x 480	31,5	60
	360 x 480	32,1	61
	376 x 564	31,5	51
	400 x 564	29,6	48
	400 x 600	29,6	45 (!)

So we can get access to almost all of the 256kB of RAM.
It depends on your monitor whether it can handle the refresh rates (down to 45Hz !). I have done testing on an old Philips 14" monitor and only had problems with the 784x588x16color mode.
Then I have tested those modes with my Miro Ergoline 1785T (that is where the H/V sync. values are from), where I had problems to get the modes below 50Hz to work properly.

David Murray also found out that in compaq`s diagnostic program you have the option to test video modes (test, graphics). When you run the tests on the internal LCD you can test these modes:
640 x 200 x 16, 640 x 350 x 16, 640 x 480 x 16 and some text modes.
But if your Aero is connected to an external monitor there is also a test on 320x200x256 available. It can only be tested on the monitor, although the LCD could easily handle it, too.

To sum up at this place, these are the video modes that can be handled by the internal LCD:

16 color	640 x 200 640 x 350 640 x 480
16 greyscales (looks great!)	640 x 480
2 (monochrom)	640 x 480
256 color	320 x 200 320 x 400 360 x 480

In Windows you can use the (great!) 16 greyscale mode by programs like for example iPhoto Plus and Image Pals from Ulead (w/o changing the windows setup, the programs will switch to that mode temselves). It does not seem to be possible to make Windows use 16 greyscales by default. Maybe we can find a driver somewhere?

On one of Compaq's pages it is written that the Aero has 512kB of video ram, this would be more than enough to support 256 colors in 640x480 (300kB are needed for that).
Compaq claims that the upper 256kB of the video ram is needed for "support of the pop up feature when coming out of standby".
As the pop up feature is the hardware cursor from the video chip (*) it only needs 1kB of RAM:
64x64 pixels in 4 colors=2 bit, this makes 64 x 64 x 1/4 = 1024 bytes

BTW: If you want to see the icons: I have them all available here.


(*) you can check this by using SPRITEST from SMOS.


So there is enough RAM available - if there really are 512kB. And there are: The RAM chip is a 4C16257DJ-7L and according to http://www.ba-karlsruhe.de/chipdir/f/dram.htm it is from Micron and is 256kB x 16bit. More information about this chip is available at http://www.micron.com/mti/marketing/htmls/datasheets/dram.html#Graphics DRAM.

The display (from Sanyo) itself is able to do 256 colors.

Unfortunately the video chip SPC8106F0b is not physically able to support 256 colors in 640x480 because it cannot get access to the upper 256kB as video RAM. This part of the memory is only available for the pop up icon.
But a later revision of this chip, the SPC8106F0c is able to access the 512kB and there are Windows drivers available for that. The 512kB - 300kB = 212kB of memory left are by far enough for one or even 212 pop up icons.
I wonder why Compaq did not go this little step to 256 colors. The RAM, the display, everything is already in the Aero's case.

And what is even more interesting:
Could it be possible that they were close to 256 colors and wanted to go to 256 colors, but then why did they not reach their goal? Time? Money?

In my eyes it is all very misterious...


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But what can we do to finally get the 256color-Windows?

At first we have to change the video chip. That means that we have to
• get the new chip (about 10$)
• find someone with the neccessary equipment, the chip is surface soldered and its pins are quite as small as the pins of the CPU. More precisely: 144pins, 20x20mm flat package. Here is a diagram of the chip (8,32kB).
• find someone who risks the live of his Aero or has a motherboard we can use
And what then?
- look what happens.

Another problem could be the video BIOS. It is not from SMOS, for it is not readable by SMOS's utilities. It is Compaq's very own BIOS.
Will it accept the new chip? - We will see if we try. I guess the BIOS will not even see a difference. Will it accept the use of the new video mode? - Well fractint can use the video modes without using the video BIOS, why should we not be able to do that, too? Or is the video BIOS even flash upgradable? - I don't think so.


Lots of unsolved questions...

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Aeronauts! We have come so far, why should we stop now? Let's go further and find out more!

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To what other questions about the video problem do we need to get answers?

There are still lots of questions to be answered:
• What exactly does the Compaq video-BIOS? Can we read / decompile and analize it? And what chip contains this BIOS? The flash upgradable Aero BIOS?
• Which of the chips on the Aero's motherboard is the RAM-DAC? - I have not found it yet...
The pictures from my motherboard and others could be of some help, too.

http://www.smos.com/web_nav/standard/graphics/graphics_directory.html