VOGONS


First post, by gemerttower

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Hi all!
Busy bringing a Vendex Headstart III back to life. All goes well so far but the videosignal: I'm only getting the screen in monochrome. The message when powering on the system:
Monochrome will be assumed unless there is a co-resident MGA installed.

I have totally no idea what that message is supposed to be. Btw, it's a CL-GD520A ISA card. Using a different card then the output is "full" color; in this case an Oaktech VGA, also ISA, using the same slot.
Card says also 9990-CVGA VER1.1 if that's of any help. Btw, I'm a bit scared of that C in CVGA 😉

Someone who can tell me what this message means, thanks!

Reply 1 of 12, by Pierre32

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Not sure if it's the same issue, but I had this symptom in my 386 with a Tseng card. It was full colour on an LCD, but detected my CRT as monochrome. I used the Trident utility 'smonitor' to fix it (it needs to run in autoexec, and no it doesn't matter that it's not a Trident video card). It's discussed here: Tseng labs ET4000AX - no color = problem

There is an alternative called 'coloron' which I haven't tried: Re: Investigating old ISA VGA cards

Reply 2 of 12, by gemerttower

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Thanks for your help. Starting MSD the splash screen is in color, then switches back to monochrome. Tried out another monitor and it's directly in color and stays in color. Weird, this is something I've never experienced before in my 30+ years of being busy in computers and so a new thing was learned today 😀

Thanks again for the help!

Pierre32 wrote on 2020-11-18, 13:16:

Not sure if it's the same issue, but I had this symptom in my 386 with a Tseng card. It was full colour on an LCD, but detected my CRT as monochrome. I used the Trident utility 'smonitor' to fix it (it needs to run in autoexec, and no it doesn't matter that it's not a Trident video card). It's discussed here: Tseng labs ET4000AX - no color = problem

There is an alternative called 'coloron' which I haven't tried: Re: Investigating old ISA VGA cards

Reply 4 of 12, by gemerttower

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Hmm, that's another very interesting idea in this case, will check that tomorrow when I'm at work again! I use this Dell monitor for various computers I'm fixing but this is the first PC where it's not giving any color from start.
The Headstart III is back in storage, but worth a test with the current VGA cable if that is the culprit.

kixs wrote on 2020-11-18, 14:13:

Have you checked the VGA cable?

Reply 5 of 12, by Jo22

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You can also turn on without the VGA cable plugged in.
Later on, plug in the VGA cable and see if colour is available.

Alternatively, run some games. Some of them do directly program the VGA card and by-pass the VGA BIOS.

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In what to one race is no time at all, another race can rise and fall..." - The Minstrel

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Reply 6 of 12, by vlask

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Have few cards like this in my collection. I guess that they have modded bios optimised for monochrome vga monitors. Because text modes are usually monochome, but if you run some graphics modes (run volkov commander or quake), they are with colors (some not with all colors).
For example STB TLI4:ERGOPowergraph with Tseng ET4000AX works like this.
http://vgamuseum.info/index.php/cards/item/46 … -tseng-et4000ax

Not only mine graphics cards collection at http://www.vgamuseum.info

Reply 7 of 12, by feipoa

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I am playing with an STB ERGO Powergraph based on ET4000AX. It has ERGO BIOS v1.6. Using the ET4000 driver, the card will display 256 colour OK in Win3.11, but when I try 32K or 64K colour, the desktop is in shades of grey. Is there any way to get this graphics card to display 32K colour, either via a TSR, or a BIOS swap?

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Reply 8 of 12, by maxtherabbit

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It's a pin detect issue. Older cards used a pin (4 IIRC) for a simple high/low monitor type detect that was then later repurposed for DDC. The DDC monitors sometimes have pullups / pulldowns on this pin so you get strange results.

The solution is to look for a jumper on the card to disconnect this pin from the VGA connector and force the signal to stay high/low. If there is no jumper you can cut a trace.

Reply 9 of 12, by BitWrangler

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Also connection on Red or Blue maybe poor, if there's only green some combinations of monitor/motherboard/VGA might take that as mono, so if your R or B is glitching it might think it's only got green.

Then another thing is older motherboards, pre-486 generally, but some legacy stuff carried into earlier boards, might have a color/mono jumper on them.

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Reply 10 of 12, by feipoa

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If it is a pin detect issue, why would I still be able to view 256 colours? Is it not more likely that the RAMDAC is 8-bit only?

Plan your life wisely, you'll be dead before you know it.

Reply 11 of 12, by feipoa

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Attached is the datasheet for the KDA0476CN-80 RAMDAC found on the STB ERGO PowerGraph ISA card.

contains 256x 18 look up table and three 6-bit video D-to-A converters... the internal data bus is only 6 bits wide and the lower 6 bits of the 8 bit input bus contain the color data

6-bit colour only?

Were there any models of the ET4000AX that could do 32K colour? When I look up the RAMDACs of images I see online, they mention this "256-word by 18-bit look-up table and triple video DAC's with 6-bit DACs"

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Reply 12 of 12, by maxtherabbit

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feipoa wrote on 2021-12-18, 22:43:

If it is a pin detect issue, why would I still be able to view 256 colours? Is it not more likely that the RAMDAC is 8-bit only?

yes, I wasn't responding to your post but to the OP - didn't realise this was a semi necro

The Diamond Speedstar24 was a high colour ET4k based card but I'm not sure if it used the AX or W32 whatever