renejr902 wrote on 2025-08-29, 15:19:

I connected the two monitor with a Oak oti037 with the d9 din 9 port and try several combinaison of switch with the oak card. even when the card switxh are set at EGA it doesnt work: monitor display is flickering/spinning. I only get the cga mode to work.

I checked several Oak 037 cards at The Retro Web, and the switch/jumper tables I found are all about the monitor type, not about the emulation type. As I understand it, you are supposed to configure the card for "CGA monitor" if you connect a CGA monitor. Otherwise, text modes and high-res graphics modes will be displayed with 350 scan lines, which is not supported by CGA monitors.

The cards I checked did not have a way to configure the emulation mode using DIP switches or jumpers, but the emulation can only be set by software, namely the VGAMODE utility. If you have software that requires an EGA card (not a VGA card), use VGAMODE to switch the card to EGA emulation. This should work even with the monitor configuration set to CGA.

So, just try setting the card to "CGA monitor" and then run software in EGA mode. It is supposed to work.

mkarcher wrote on 2025-08-29, 15:55:

I checked several Oak 037 cards at The Retro Web, and the switch/jumper tables I found are all about the monitor type, not about […]
Show full quote

renejr902 wrote on 2025-08-29, 15:19:

I connected the two monitor with a Oak oti037 with the d9 din 9 port and try several combinaison of switch with the oak card. even when the card switxh are set at EGA it doesnt work: monitor display is flickering/spinning. I only get the cga mode to work.

I checked several Oak 037 cards at The Retro Web, and the switch/jumper tables I found are all about the monitor type, not about the emulation type. As I understand it, you are supposed to configure the card for "CGA monitor" if you connect a CGA monitor. Otherwise, text modes and high-res graphics modes will be displayed with 350 scan lines, which is not supported by CGA monitors.

The cards I checked did not have a way to configure the emulation mode using DIP switches or jumpers, but the emulation can only be set by software, namely the VGAMODE utility. If you have software that requires an EGA card (not a VGA card), use VGAMODE to switch the card to EGA emulation. This should work even with the monitor configuration set to CGA.

So, just try setting the card to "CGA monitor" and then run software in EGA mode. It is supposed to work.

Sadly, i already did that several time. In CGA switch mode, It doesnt work with vgamode.exe in ega mode When i choose ega it doesnt register at all. Even then i tried several ega games and no one can show the screen, its all black. I used vgamode.exe often in the past because i use a vga card in cga mode that work fairly good.

Thanks for your help. If you have other idea ley me know, thanks a lot

( maybe i could uae my vga monitor in ega, but i do t want to do that. i love the digital color and image quality of my two cga monitor, i want to use them with 16 colors ega mode even in low resolution )

renejr902 wrote on 2025-08-29, 15:58:

mkarcher wrote on 2025-08-29, 15:55:

I checked several Oak 037 cards at The Retro Web, and the switch/jumper tables I found are all about the monitor type, not about […]
Show full quote

renejr902 wrote on 2025-08-29, 15:19:

I connected the two monitor with a Oak oti037 with the d9 din 9 port and try several combinaison of switch with the oak card. even when the card switxh are set at EGA it doesnt work: monitor display is flickering/spinning. I only get the cga mode to work.

I checked several Oak 037 cards at The Retro Web, and the switch/jumper tables I found are all about the monitor type, not about the emulation type. As I understand it, you are supposed to configure the card for "CGA monitor" if you connect a CGA monitor. Otherwise, text modes and high-res graphics modes will be displayed with 350 scan lines, which is not supported by CGA monitors.

The cards I checked did not have a way to configure the emulation mode using DIP switches or jumpers, but the emulation can only be set by software, namely the VGAMODE utility. If you have software that requires an EGA card (not a VGA card), use VGAMODE to switch the card to EGA emulation. This should work even with the monitor configuration set to CGA.

So, just try setting the card to "CGA monitor" and then run software in EGA mode. It is supposed to work.

Sadly, i already did that several time. In CGA switch mode, It doesnt work with vgamode.exe in ega mode When i choose ega it dont register at all. Even then i tried several ega games and no one can show the screen, its all black. I used vgamode.exe often in the past because i use a vga card in cga mode that work fairly good.

Yeah, I'm sorry, I should have read the manual one page farther than I did. It clearly says: "If the switch setting is set to digital monitor, such as EGA, CGA, etc., then the emulation will be brought up right after system boot up. In this case, you don't have to run VGAMODE to turn on emulation."

So it seems the BIOS is not designed to emulate "EGA with CGA monitor", which is unfortunate. If the BIOS is fully EGA compatible in EGA emulation mode is, you should be able to get the BIOS to use CGA compatible text modes by running "e40:88 7" in debug. If you then re-initialize the text mode (e.g. "MODE CO80"), you should get a CGA-type text mode.

mkarcher wrote on 2025-08-29, 16:14:

renejr902 wrote on 2025-08-29, 15:58:

mkarcher wrote on 2025-08-29, 15:55:

I checked several Oak 037 cards at The Retro Web, and the switch/jumper tables I found are all about the monitor type, not about the emulation type. As I understand it, you are supposed to configure the card for "CGA monitor" if you connect a CGA monitor. Otherwise, text modes and high-res graphics modes will be displayed with 350 scan lines, which is not supported by CGA monitors.

The cards I checked did not have a way to configure the emulation mode using DIP switches or jumpers, but the emulation can only be set by software, namely the VGAMODE utility. If you have software that requires an EGA card (not a VGA card), use VGAMODE to switch the card to EGA emulation. This should work even with the monitor configuration set to CGA.

So, just try setting the card to "CGA monitor" and then run software in EGA mode. It is supposed to work.

Sadly, i already did that several time. In CGA switch mode, It doesnt work with vgamode.exe in ega mode When i choose ega it dont register at all. Even then i tried several ega games and no one can show the screen, its all black. I used vgamode.exe often in the past because i use a vga card in cga mode that work fairly good.

Yeah, I'm sorry, I should have read the manual one page farther than I did. It clearly says: "If the switch setting is set to digital monitor, such as EGA, CGA, etc., then the emulation will be brought up right after system boot up. In this case, you don't have to run VGAMODE to turn on emulation."

So it seems the BIOS is not designed to emulate "EGA with CGA monitor", which is unfortunate. If the BIOS is fully EGA compatible in EGA emulation mode is, you should be able to get the BIOS to use CGA compatible text modes by running "e40:88 7" in debug. If you then re-initialize the text mode (e.g. "MODE CO80"), you should get a CGA-type text mode.

it sad. i will buy another ega card, a normal one. I dont understand your debug thing...

renejr902 wrote on 2025-08-29, 16:20:

mkarcher wrote on 2025-08-29, 16:14:

renejr902 wrote on 2025-08-29, 15:58:

Sadly, i already did that several time. In CGA switch mode, It doesnt work with vgamode.exe in ega mode When i choose ega it dont register at all. Even then i tried several ega games and no one can show the screen, its all black. I used vgamode.exe often in the past because i use a vga card in cga mode that work fairly good.

Yeah, I'm sorry, I should have read the manual one page farther than I did. It clearly says: "If the switch setting is set to digital monitor, such as EGA, CGA, etc., then the emulation will be brought up right after system boot up. In this case, you don't have to run VGAMODE to turn on emulation."

So it seems the BIOS is not designed to emulate "EGA with CGA monitor", which is unfortunate. If the BIOS is fully EGA compatible in EGA emulation mode is, you should be able to get the BIOS to use CGA compatible text modes by running "e40:88 7" in debug. If you then re-initialize the text mode (e.g. "MODE CO80"), you should get a CGA-type text mode.

it sad. i will buy another ega card, a normal one. I dont understand your debug thing...

I tried to suggest the following: You configure the OAK card to "EGA", and then you boot your system. You will not get a usable imag on the CGA monitor. You then blindly type DEBUG and press the enter key. This will start the DEBUG utility shipped with MS-DOS. DEBUG will display a single dash "-" as prompt, and you type (still blindly) "e40:88 7" and press enter. This configures any EGA compatible BIOS to use CGA compatible monitor frequencies. Assuming your OAK BIOS is sufficiently EGA compatible, it should accept this configuration as well. Then you type "q" and press enter again, to quit debug. This will return you to the DOS prompt. Finally, you type "MODE CO80", to re-initialize the text mode. The BIOS is supposed to check for the configuration byte in the BIOS configuration area we just modified, and select the CGA-compatible variant of the text mode instead of the EGA-only variant, so the monitor should start to sync.

If this helps, I can instruct you how to automate this process, so that is will be performed at every boot.

mkarcher wrote on 2025-08-29, 16:25:

renejr902 wrote on 2025-08-29, 16:20:

mkarcher wrote on 2025-08-29, 16:14:

Yeah, I'm sorry, I should have read the manual one page farther than I did. It clearly says: "If the switch setting is set to digital monitor, such as EGA, CGA, etc., then the emulation will be brought up right after system boot up. In this case, you don't have to run VGAMODE to turn on emulation."

So it seems the BIOS is not designed to emulate "EGA with CGA monitor", which is unfortunate. If the BIOS is fully EGA compatible in EGA emulation mode is, you should be able to get the BIOS to use CGA compatible text modes by running "e40:88 7" in debug. If you then re-initialize the text mode (e.g. "MODE CO80"), you should get a CGA-type text mode.

it sad. i will buy another ega card, a normal one. I dont understand your debug thing...

I tried to suggest the following: You configure the OAK card to "EGA", and then you boot your system. You will not get a usable imag on the CGA monitor. You then blindly type DEBUG and press the enter key. This will start the DEBUG utility shipped with MS-DOS. DEBUG will display a single dash "-" as prompt, and you type (still blindly) "e40:88 7" and press enter. This configures any EGA compatible BIOS to use CGA compatible monitor frequencies. Assuming your OAK BIOS is sufficiently EGA compatible, it should accept this configuration as well. Then you type "q" and press enter again, to quit debug. This will return you to the DOS prompt. Finally, you type "MODE CO80", to re-initialize the text mode. The BIOS is supposed to check for the configuration byte in the BIOS configuration area we just modified, and select the CGA-compatible variant of the text mode instead of the EGA-only variant, so the monitor should start to sync.

If this helps, I can instruct you how to automate this process, so that is will be performed at every boot.

I got something working before i read your explanation. i let you know

I put the switch back to ega.

and boot the pc with the gambled screen.

at C: i wrote " vgamode 0D "

and the screen come up. i sent you a picture. and a picture where i found this information in the manual.
but i foumd resolution strange a little.

About your debug i didnt found it in dos directory. i use dos 6.22 ( maybe i erase it because i need space 🤣 ) i have a xt-ide card, but in this one i use the original mfm drive 80mb. 4 partition of 20mb. But only C: and D: work correctly. But i remember to have copy all dos disk in F:, but f dont want to work anymore like before say general failure after i copy anything in it. So my only way to copy stuff is to open the computer put my special cable with 1.44mb and boot with a 1.44mb special utilie on a 360kb disk.

For now can get it working using my trick ? until i get a way to copy back debug on c: ?

Thanks so much for help.

Your idea impress me a lot. I thought i have great abilities in dos, but never know about debug in dos and your idea is awesome. i would never find this idea. as soon as i get debug on disk i try it

I got something working before i read your explanation. i let you know

I put the switch back to ega.

and boot the pc with the gambled screen.

at C: i wrote " vgamode 0D "

and the screen come up. i sent you a picture. and a picture where i found this information in the manual.
but i foumd resolution strange a little.

About your debug i didnt found it in dos directory. i use dos 6.22 ( maybe i erase it because i need space 🤣 ) i have a xt-ide card, but in this one i use the original mfm drive 80mb. 4 partition of 20mb. But only C: and D: work correctly. But i remember to have copy all dos disk in F:, but f dont want to work anymore like before say general failure after i copy anything in it. So my only way to copy stuff is to open the computer put my special cable with 1.44mb and boot with a 1.44mb special utilie on a 360kb disk.

For now can get it working using my trick ? until i get a way to copy back debug on c: ?

Thanks so much for help.

Your idea impress me a lot. I thought i have great abilities in dos, but never know about debug in dos and your idea is awesome. i would never find this idea. as soon as i get debug on disk i try it

renejr902 wrote on 2025-08-29, 17:16:

I got something working before i read your explanation. i let you know […]
Show full quote

mkarcher wrote on 2025-08-29, 16:25:

renejr902 wrote on 2025-08-29, 16:20:

it sad. i will buy another ega card, a normal one. I dont understand your debug thing...

I tried to suggest the following: You configure the OAK card to "EGA", and then you boot your system. You will not get a usable imag on the CGA monitor. You then blindly type DEBUG and press the enter key. This will start the DEBUG utility shipped with MS-DOS. DEBUG will display a single dash "-" as prompt, and you type (still blindly) "e40:88 7" and press enter. This configures any EGA compatible BIOS to use CGA compatible monitor frequencies. Assuming your OAK BIOS is sufficiently EGA compatible, it should accept this configuration as well. Then you type "q" and press enter again, to quit debug. This will return you to the DOS prompt. Finally, you type "MODE CO80", to re-initialize the text mode. The BIOS is supposed to check for the configuration byte in the BIOS configuration area we just modified, and select the CGA-compatible variant of the text mode instead of the EGA-only variant, so the monitor should start to sync.

If this helps, I can instruct you how to automate this process, so that is will be performed at every boot.

I got something working before i read your explanation. i let you know

I put the switch back to ega.

and boot the pc with the gambled screen.

at C: i wrote " vgamode 0D "

and the screen come up. i sent you a picture. and a picture where i found this information in the manual.
but i foumd resolution strange a little.

About your debug i didnt found it in dos directory. i use dos 6.22 ( maybe i erase it because i need space 🤣 ) i have a xt-ide card, but in this one i use the original mfm drive 80mb. 4 partition of 20mb. But only C: and D: work correctly. But i remember to have copy all dos disk in F:, but f dont want to work anymore like before say general failure after i copy anything in it. So my only way to copy stuff is to open the computer put my special cable with 1.44mb and boot with a 1.44mb special utilie on a 360kb disk.

For now can get it working using my trick ? until i get a way to copy back debug on c: ?

Thanks so much for help.

Your idea impress me a lot. I thought i have great abilities in dos, but never know about debug in dos and your idea is awesome. i would never find this idea. as soon as i get debug on disk i try it

as soon as i start a ega game, the gambled screen is back. i dont know what to do

vgamode 0E works too. and resolution looks normal, but i soon i started any ega games, scambled screen is back.

I suppose i have to install debug in some way. right ? thanks for answer

Let me know if we can do something about this trick i found with the manual, otherwise i will find a way to copy debug from dos 6.22 thanks

renejr902 wrote on 2025-08-29, 17:16:

I got something working before i read your explanation. i let you know […]
Show full quote

mkarcher wrote on 2025-08-29, 16:25:

renejr902 wrote on 2025-08-29, 16:20:

it sad. i will buy another ega card, a normal one. I dont understand your debug thing...

I tried to suggest the following: You configure the OAK card to "EGA", and then you boot your system. You will not get a usable imag on the CGA monitor. You then blindly type DEBUG and press the enter key. This will start the DEBUG utility shipped with MS-DOS. DEBUG will display a single dash "-" as prompt, and you type (still blindly) "e40:88 7" and press enter. This configures any EGA compatible BIOS to use CGA compatible monitor frequencies. Assuming your OAK BIOS is sufficiently EGA compatible, it should accept this configuration as well. Then you type "q" and press enter again, to quit debug. This will return you to the DOS prompt. Finally, you type "MODE CO80", to re-initialize the text mode. The BIOS is supposed to check for the configuration byte in the BIOS configuration area we just modified, and select the CGA-compatible variant of the text mode instead of the EGA-only variant, so the monitor should start to sync.

If this helps, I can instruct you how to automate this process, so that is will be performed at every boot.

I got something working before i read your explanation. i let you know

I put the switch back to ega.

and boot the pc with the gambled screen.

at C: i wrote " vgamode 0D "

and the screen come up. i sent you a picture. and a picture where i found this information in the manual.
but i foumd resolution strange a little.

About your debug i didnt found it in dos directory. i use dos 6.22 ( maybe i erase it because i need space 🤣 ) i have a xt-ide card, but in this one i use the original mfm drive 80mb. 4 partition of 20mb. But only C: and D: work correctly. But i remember to have copy all dos disk in F:, but f dont want to work anymore like before say general failure after i copy anything in it. So my only way to copy stuff is to open the computer put my special cable with 1.44mb and boot with a 1.44mb special utilie on a 360kb disk.

For now can get it working using my trick ? until i get a way to copy back debug on c: ?

Thanks so much for help.

Your idea impress me a lot. I thought i have great abilities in dos, but never know about debug in dos and your idea is awesome. i would never find this idea. as soon as i get debug on disk i try it

i succeed to read f: and disk1 folder and i copied debug, i will let you know now

mkarcher wrote on 2025-08-29, 16:25:

renejr902 wrote on 2025-08-29, 16:20:

mkarcher wrote on 2025-08-29, 16:14:

Yeah, I'm sorry, I should have read the manual one page farther than I did. It clearly says: "If the switch setting is set to digital monitor, such as EGA, CGA, etc., then the emulation will be brought up right after system boot up. In this case, you don't have to run VGAMODE to turn on emulation."

So it seems the BIOS is not designed to emulate "EGA with CGA monitor", which is unfortunate. If the BIOS is fully EGA compatible in EGA emulation mode is, you should be able to get the BIOS to use CGA compatible text modes by running "e40:88 7" in debug. If you then re-initialize the text mode (e.g. "MODE CO80"), you should get a CGA-type text mode.

it sad. i will buy another ega card, a normal one. I dont understand your debug thing...

I tried to suggest the following: You configure the OAK card to "EGA", and then you boot your system. You will not get a usable imag on the CGA monitor. You then blindly type DEBUG and press the enter key. This will start the DEBUG utility shipped with MS-DOS. DEBUG will display a single dash "-" as prompt, and you type (still blindly) "e40:88 7" and press enter. This configures any EGA compatible BIOS to use CGA compatible monitor frequencies. Assuming your OAK BIOS is sufficiently EGA compatible, it should accept this configuration as well. Then you type "q" and press enter again, to quit debug. This will return you to the DOS prompt. Finally, you type "MODE CO80", to re-initialize the text mode. The BIOS is supposed to check for the configuration byte in the BIOS configuration area we just modified, and select the CGA-compatible variant of the text mode instead of the EGA-only variant, so the monitor should start to sync.

If this helps, I can instruct you how to automate this process, so that is will be performed at every boot.

🤣 i got it working perfectly but not exactly like you said. to me all seems correct i tried a few ega games and sysinfo.

Let me explain you why...

I enter debug
put e40:88 7
enter
q
enter

all was ok

But i tried for 5 minutes but i have to copy mode.com from f: but this time the file was corrupted. it still copy it but when executing it frooze the pc everytime

So i have the idea after the debug thing to do this:

VGAMODE C " enter " ( before it was not working still gambled screen)

But now it works the screen sync again and sysinfo still detect ega card and every game work as intended. to me the screen is normal. i sent you a pic.

If you thing all is ok by my picture, let me know how to automatic the debug thing, if i can add it to autoexec.bat or another way.

THANKS SO MUCH ITS REALLY APPRECIATED without you i would not have succeed, the e:40:88 7
did the truck 😀 i'm very happy, i start playing ega games on this wonderful monitor. I'm sorry pictures are blurred, i tried the best i could 😀

When you have time, let me know about that:

" If this helps, I can instruct you how to automate this process, so that is will be performed at every boot "

thanks a lot

pictures Bubble Bobble ega video card on ibm 5153 cga monitor

Please test first whether "VGAMODE C" does the trick even without my DEBUG commands. Actually, I am surprised that "VGAMODE C" does not switch to "CGA emulation" which would disable all EGA capabilities. If you really need the DEBUG stuff, create a file with the following contents

1e40:88 7
2a100
3mov ax,3
4int 10
5int 3
6
7g
8q

and save it as "C:\CGAMON.DBG", then you can add DEBUG < C:\CGAMON.DBG to your AUTOEXEC.BAT. I also included the command to reinitialize the text mode, so possibly you don't even need to call VGAMODE afterwards. If this does not work, and you need VGAMODE C, you can shorten the CGAMON.DBG file to the first line (e40:88 7) and the last line (q).

mkarcher wrote on 2025-08-29, 20:25:

Please test first whether "VGAMODE C" does the trick even without my DEBUG commands. Actually, I am surprised that "VGAMODE C" d […]
Show full quote

Please test first whether "VGAMODE C" does the trick even without my DEBUG commands. Actually, I am surprised that "VGAMODE C" does not switch to "CGA emulation" which would disable all EGA capabilities. If you really need the DEBUG stuff, create a file with the following contents

Copy code to clipboard

1e40:88 7
2a100
3mov ax,3
4int 10
5int 3
6
7g
8q

and save it as "C:\CGAMON.DBG", then you can add DEBUG < C:\CGAMON.DBG to your AUTOEXEC.BAT. I also included the command to reinitialize the text mode, so possibly you don't even need to call VGAMODE afterwards. If this does not work, and you need VGAMODE C, you can shorten the CGAMON.DBG file to the first line (e40:88 7) and the last line (q).

no, only vgamode c at boot doesnt work, it does nothing. thanks for the info about automate, its really appreciate