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First post, by eesz34

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I have a Prolinea 3/25 that has a WD90C31 video chip and am wondering if it can display more than 256 colors at lower resolutions. Since it has 512KB RAM, I know anything beyond 256 colors at 640x480 is an impossibility. But I'm trying to determine if maybe 320x200 can do more colors on the screen.

I looked at the WD datasheet, and it doesn't mention true color, and I tend to think it's limited to 256 colors as there's no evidence it can do more. I believe the color register is only 8 bits, but I'm a bit confused by how this works on VGA.

So then I looked at the RAMDAC thinking that might tell me if that limits it to 256 color, making the question of the controller chip moot. That has triple 6 bit DACs so it's clearly capable, and the question still remains.

Am I correct in assuming this can do 256 colors at most on the screen? Is there a good DOS utility that tests this sort of thing?

Reply 1 of 18, by pentiumspeed

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wd90C30 and 31 supports 1MB and also enables full bandwidth. Looks like you need to hunt down 512K module to bring up to 1MB.

Cheers,

Great Northern aka Canada.

Reply 2 of 18, by The Serpent Rider

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Is there a good DOS utility that tests this sort of thing?

Scitech Display Doctor, which is a part of UniVBE package.

Last edited by The Serpent Rider on 2022-02-16, 18:37. Edited 1 time in total.

I must be some kind of standard: the anonymous gangbanger of the 21st century.

Reply 3 of 18, by Jo22

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I've never really got Scitech software to work. 🙁
However, at least one of these old VBE drivers from the manufacturers did work often.

Re: OAK OTI-037c - 800x600 mode ?

Often, Windows 3.1x software works best in 256c, by the way .
256c mode allows palette cycling, also.
Windows programs or games that run full-screen expect 640x480 resolution.
Or 800x600, in some cases.

Edit: The VGA core of Western Digital (WD) graphics chipsets (WD90Cxx) is backwards compatible with the Paradise Professional VGA (PVGA 1A etc).

It's even possible to use ancient Windows 2.x drivers with the newer WD chips. 😀

"Time, it seems, doesn't flow. For some it's fast, for some it's slow.
In what to one race is no time at all, another race can rise and fall..." - The Minstrel

//My video channel//

Reply 4 of 18, by Grzyb

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eesz34 wrote on 2022-02-16, 15:31:

So then I looked at the RAMDAC thinking that might tell me if that limits it to 256 color, making the question of the controller chip moot. That has triple 6 bit DACs so it's clearly capable, and the question still remains.

Every VGA RAMDAC has three 6-bit DACs, therefore 2^18 colors - but not simultaneously.
What exactly RAMDAC you have?

Reply 5 of 18, by eesz34

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pentiumspeed wrote on 2022-02-16, 17:27:

wd90C30 and 31 supports 1MB and also enables full bandwidth. Looks like you need to hunt down 512K module to bring up to 1MB.

Cheers,

Don't think that'll be possible. There's no way to add VRAM to this board.

Reply 6 of 18, by eesz34

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Grzyb wrote on 2022-02-16, 18:20:
eesz34 wrote on 2022-02-16, 15:31:

So then I looked at the RAMDAC thinking that might tell me if that limits it to 256 color, making the question of the controller chip moot. That has triple 6 bit DACs so it's clearly capable, and the question still remains.

Every VGA RAMDAC has three 6-bit DACs, therefore 2^18 colors - but not simultaneously.
What exactly RAMDAC you have?

Couldn't you have every pixel on a 1280x1024 output (1.3 million pixels) have a different color though? That would exceed 18 bit capability. It would be over 2MB RAM but I believe there are adapters with 4MB?

Anyway, it's KDA0476CN-66.

Reply 7 of 18, by eesz34

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Jo22 wrote on 2022-02-16, 17:46:
I've never really got Scitech software to work. :( However, at least one of these old VBE drivers from the manufacturers did wor […]
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I've never really got Scitech software to work. 🙁
However, at least one of these old VBE drivers from the manufacturers did work often.

Re: OAK OTI-037c - 800x600 mode ?

Often, Windows 3.1x software works best in 256c, by the way .
256c mode allows palette cycling, also.
Windows programs or games that run full-screen expect 640x480 resolution.
Or 800x600, in some cases.

Edit: The VGA core of Western Digital (WD) graphics chipsets (WD90Cxx) is backwards compatible with the Paradise Professional VGA (PVGA 1A etc).

It's even possible to use ancient Windows 2.x drivers with the newer WD chips. 😀

Cool, I'll try the vgamode utility.

Reply 8 of 18, by Jo22

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Good luck! Could be that the WD cards need another utility.
I'll check my archive..

"Time, it seems, doesn't flow. For some it's fast, for some it's slow.
In what to one race is no time at all, another race can rise and fall..." - The Minstrel

//My video channel//

Reply 9 of 18, by bakemono

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NEC Versa V/50 has a WD90C24a video chip with 512KB that can do 15-bit color (or maybe it does 'true' 16-bit, I can't remember). If 90C31 is newer or more advanced than 90C24 then I expect it can also. The VBETEST or PROFILE utilities included with the SDD package can display a list of available VESA modes, either those supported by the BIOS or after UniVBE is installed.

yet another retro game on itch: https://90soft90.itch.io/super-wild-war-22

Reply 10 of 18, by eesz34

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eesz34 wrote on 2022-02-16, 15:31:

I have a Prolinea 3/25 that has a WD90C31 video chip and am wondering if it can display more than 256 colors at lower resolutions. Since it has 512KB RAM, I know anything beyond 256 colors at 640x480 is an impossibility. But I'm trying to determine if maybe 320x200 can do more colors on the screen.

OOPS! This is a WD90C30, not 31! I think I got mixed up because the original motherboard in this thing has a WD90C11 (it ends in a '1').

Ok, so not sure of the difference between the two because I haven't investigated that yet. Uggh..

I just took a photo of the video section because I know some like PCB porn, well I do anyway. And yeah, I then realized the mistake. This computer is everything I used to be against: integrated stuff, proprietary, little room for expansion. But it seemed nobody wanted it and I remembered them as a kid.

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Reply 11 of 18, by darry

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eesz34 wrote on 2022-02-16, 22:53:
OOPS! This is a WD90C30, not 31! I think I got mixed up because the original motherboard in this thing has a WD90C11 (it ends in […]
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eesz34 wrote on 2022-02-16, 15:31:

I have a Prolinea 3/25 that has a WD90C31 video chip and am wondering if it can display more than 256 colors at lower resolutions. Since it has 512KB RAM, I know anything beyond 256 colors at 640x480 is an impossibility. But I'm trying to determine if maybe 320x200 can do more colors on the screen.

OOPS! This is a WD90C30, not 31! I think I got mixed up because the original motherboard in this thing has a WD90C11 (it ends in a '1').

Ok, so not sure of the difference between the two because I haven't investigated that yet. Uggh..

I just took a photo of the video section because I know some like PCB porn, well I do anyway. And yeah, I then realized the mistake. This computer is everything I used to be against: integrated stuff, proprietary, little room for expansion. But it seemed nobody wanted it and I remembered them as a kid.

As far as I understand it, the KDA0476CN-66 forces you to use its color palette SRAM, which has 256 18 bit entries ( http://pdf.datasheetcatalog.com/datasheet_pdf … DA0478PL-80.pdf ), so 256 colors from an 18 bit palette (6 bits each for red, green and blue) can be displayed simultaneously, whatever the resolution . On this point, it is the same as INMOS RAMDAC in the original IBM VGA .

Reply 12 of 18, by pentiumspeed

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You should given a full model, which is: Prolinea 3/25zs

I had been looking for one as I wanted this cute little computer, no luck. Seen one once years ago.

Cheers,

Great Northern aka Canada.

Reply 13 of 18, by eesz34

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pentiumspeed wrote on 2022-02-17, 13:20:

You should given a full model, which is: Prolinea 3/25zs

I had been looking for one as I wanted this cute little computer, no luck. Seen one once years ago.

Cheers,

Correct, 3/25zs. Although a Compaq diagnostic utility says it's a 3/25s, but it's not the original MB either. The original MB has heavy damage from a leaking battery which I will be fixing eventually. So the board in there now might be from a 3/25s. The I/O plate was slightly different and had to be swapped, so that could be the case.

This computer has an interesting history from what I can tell. I picked this up from eBay recently as not working. It was listed for at least 4 months because that was the last and only listing revision, so I offered the seller very little for it and they accepted (shipping was about 75% of the cost, all within the US, if that tells you anything).

The only problem was a shorted/smoked tantalum cap on the MB, +12V rail. However it still wouldn't boot because Compaqs apparently won't without a CMOS battery and instead blames it on the floppy controller Ha ha. So that's when I put in the other MB I also picked up. That had battery damage too, but very limited. Interestingly, the same cap on that one blew when I powered it. But I have since replaced that also and it's fine now.

The most recent file on the hard drive makes me think this was last successfully booted in '94 or '95. It was made in the UK, and although the owner left very little evidence of use on the hard drive, he did leave his resume in an Excel file (complete with his address in the UK but worked in TX for a time) and a wallpaper (256 color image of course) of his kids. So my guess is this was shuffled around for around 28 years, never working.

This is my very first retro computer purchase. I've been window shopping for many years but always rationalized my way out of it. The local computer store sold these when I was a kid and I always wanted one, but didn't get one until now!

You're right though, for some reason far more 486 Prolineas appear on eBay. I haven't seen a 386 since, but admittingly it hasn't been that long.

Reply 14 of 18, by bigern77

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eesz34 wrote on 2022-02-16, 15:31:
I have a Prolinea 3/25 that has a WD90C31 video chip and am wondering if it can display more than 256 colors at lower resolution […]
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I have a Prolinea 3/25 that has a WD90C31 video chip and am wondering if it can display more than 256 colors at lower resolutions. Since it has 512KB RAM, I know anything beyond 256 colors at 640x480 is an impossibility. But I'm trying to determine if maybe 320x200 can do more colors on the screen.

I looked at the WD datasheet, and it doesn't mention true color, and I tend to think it's limited to 256 colors as there's no evidence it can do more. I believe the color register is only 8 bits, but I'm a bit confused by how this works on VGA.

So then I looked at the RAMDAC thinking that might tell me if that limits it to 256 color, making the question of the controller chip moot. That has triple 6 bit DACs so it's clearly capable, and the question still remains.

Am I correct in assuming this can do 256 colors at most on the screen? Is there a good DOS utility that tests this sort of thing?

Hi. Did you ever find a way to display >256 colors? I have a WD90C31A-LR. The PROFILE utility reports that it has 1MB RAM, but it apparently only supports modes having a maximum of 256 colors.

Reply 15 of 18, by eesz34

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bigern77 wrote on 2022-08-10, 00:52:
eesz34 wrote on 2022-02-16, 15:31:
I have a Prolinea 3/25 that has a WD90C31 video chip and am wondering if it can display more than 256 colors at lower resolution […]
Show full quote

I have a Prolinea 3/25 that has a WD90C31 video chip and am wondering if it can display more than 256 colors at lower resolutions. Since it has 512KB RAM, I know anything beyond 256 colors at 640x480 is an impossibility. But I'm trying to determine if maybe 320x200 can do more colors on the screen.

I looked at the WD datasheet, and it doesn't mention true color, and I tend to think it's limited to 256 colors as there's no evidence it can do more. I believe the color register is only 8 bits, but I'm a bit confused by how this works on VGA.

So then I looked at the RAMDAC thinking that might tell me if that limits it to 256 color, making the question of the controller chip moot. That has triple 6 bit DACs so it's clearly capable, and the question still remains.

Am I correct in assuming this can do 256 colors at most on the screen? Is there a good DOS utility that tests this sort of thing?

Hi. Did you ever find a way to display >256 colors? I have a WD90C31A-LR. The PROFILE utility reports that it has 1MB RAM, but it apparently only supports modes having a maximum of 256 colors.

That appears correct. Nothing I ever found could display over 256 colors. I believe the datasheet for the video controller even stated something like "up to 256 colors".

Reply 16 of 18, by keropi

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256 colors is a ramdac limitation
90c31 can display more with a suitable ramdac, diamond for example has a 24bit ramdac on their speedstar24x vga

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Reply 17 of 18, by mkarcher

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eesz34 wrote on 2022-08-15, 12:31:

That appears correct. Nothing I ever found could display over 256 colors. I believe the datasheet for the video controller even stated something like "up to 256 colors".

Using a suitable RAMDAC, you can program the video controller to output 640x200 at 256 colors, and have the RAMDAC take the two 8-bit values that are meant for neighbouring pixels to combine them into one 16-bit value that is output during the duration of two pixels, so the actual image output will be 320x200 at 64K colors. Additionally to the RAMDAC chip, you would need a BIOS or driver capable of setting up the RAMDAC to 64K mode and programming the WD chip to the double horizontal resolution. I don't know whether a BIOS like that has ever been written for the WD90C30 or WD90C31, as I don't know whether anyone actually combined these graphics chips with truecolor-capable RAMDACs.

High-color capable DACs that can be combined with any SVGA graphics chip designed for 256 colors include the Booktree Bt481/Bt482 (SMD conly), and the later Sierra SC1148x models (available in DIP-28 or SMD). There are also a lot other manufacturers providing Sierra-like DACs.

Reply 18 of 18, by keropi

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I found an old post of mine with the Speedstar24x driver: Re: Windows 3.1 drivers for Diamond Speedstar 24x
apparently with 1mb vram the max color depth is 16mil at 640x480
but realistically - even though the chip is a fast ISA one - things get slow with high color depths

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