Prez wrote on 2020-08-14, 12:21:

Hi all ! […]
Show full quote

Hi all !

Just received another VGA2HDMI cheap device that works great under DOS mode 70Hz !
20200814_075848.jpg
20200814_075853.jpg

I will upload a video of Doom working on it.
It seems to be this one :
https://fr.aliexpress.com/item/32692452101.ht … .46f47ed3pf2rTs

Best regards
Philippe Dubois

Hi Prez,
Everyone,

I've just tried this cheap ass "AIXXCO brand" VGA to HDMI converter that Prez suggests. It's still available on Aliexpress as of Q2 2021 and yeah, it really works @70Hz in DOS.
It handles resolution changes quickly. Sometimes faster than my 2010s Fujitsu Siemens 4:3 TFT monitor and that "Foinnex brand" (also suggested by someone) that couldn't handle 70Hz at 320x200 or 700x400.
Keep in mind: it only supports resolutions at and over 800x600 in the specs. I've tested it on my 486 rig equipped with a VLB CL-GD5428. Stepping through the resolutions in CLUTIL some more specific resolutions+refresh rates show up slightly under- or overscanned (image border/sides are off the screen, mostly to the right). So It's not flawless, but works nice with most games for this price tag.
Now I'm opening it up and checking out what makes it tick. I hope it's not some "licensed" custom or not well known obsolete chinese ASIC. 😀
This is the URL I've bought it from a month ago: https://www.aliexpress.com/item/32692452101.html

Note on some "el cheapo" webcam based USB video class (UVC) HDMI capture devices: I've had some brightness/saturation/etc. issues with it, because factory programmed default values are not right. But! changeable. I'm using OBS and V4L2 (Video for linux2). You have to try to avoid MJPEG output if you want small text to be real crisp and free from discrete cosine transform (DCT) artifacts. This comes with a caveat, because most of these dongles want to look like USB3, but most are only 2.0 High Speed (HS). This means that uncompressed raw video (e.g. YUYV) will have a limitation either on framerate or maximum resolution, whichever you choose (game capture at 5FPS is not great). You simply can't dunk down like 2.1+MPixels (1920x1080@30...60Hz uncompressed on USB2. It's worth looking for true USB3 capture dongles in the future to avoid this huge limitation.

I've did some image optimizations, thanks to this fellow's research:
http://ciko.io/posts/cheap_usb_hdmi/
http://ciko.io/posts/cheap_usb_hdmi_2/
It uses test images or a color card and opencv, then compares it to input data.

Thanks again to Prez and that ciko.io author!

Cheers,
Chris

christal87 wrote on 2021-07-27, 18:48:

Hi Prez, Everyone, […]
Show full quote

Prez wrote on 2020-08-14, 12:21:

Hi all ! […]
Show full quote

Hi all !

Just received another VGA2HDMI cheap device that works great under DOS mode 70Hz !
20200814_075848.jpg
20200814_075853.jpg

I will upload a video of Doom working on it.
It seems to be this one :
https://fr.aliexpress.com/item/32692452101.ht … .46f47ed3pf2rTs

Best regards
Philippe Dubois

Hi Prez,
Everyone,

I've just tried this cheap ass "AIXXCO brand" VGA to HDMI converter that Prez suggests. It's still available on Aliexpress as of Q2 2021 and yeah, it really works @70Hz in DOS.
It handles resolution changes quickly. Sometimes faster than my 2010s Fujitsu Siemens 4:3 TFT monitor and that "Foinnex brand" (also suggested by someone) that couldn't handle 70Hz at 320x200 or 700x400.
Keep in mind: it only supports resolutions at and over 800x600 in the specs. I've tested it on my 486 rig equipped with a VLB CL-GD5428. Stepping through the resolutions in CLUTIL some more specific resolutions+refresh rates show up slightly under- or overscanned (image border/sides are off the screen, mostly to the right). So It's not flawless, but works nice with most games for this price tag.
Now I'm opening it up and checking out what makes it tick. I hope it's not some "licensed" custom or not well known obsolete chinese ASIC. 😀
This is the URL I've bought it from a month ago: https://www.aliexpress.com/item/32692452101.html

Note on some "el cheapo" webcam based USB video class (UVC) HDMI capture devices: I've had some brightness/saturation/etc. issues with it, because factory programmed default values are not right. But! changeable. I'm using OBS and V4L2 (Video for linux2). You have to try to avoid MJPEG output if you want small text to be real crisp and free from discrete cosine transform (DCT) artifacts. This comes with a caveat, because most of these dongles want to look like USB3, but most are only 2.0 High Speed (HS). This means that uncompressed raw video (e.g. YUYV) will have a limitation either on framerate or maximum resolution, whichever you choose (game capture at 5FPS is not great). You simply can't dunk down like 2.1+MPixels (1920x1080@30...60Hz uncompressed on USB2. It's worth looking for true USB3 capture dongles in the future to avoid this huge limitation.

I've did some image optimizations, thanks to this fellow's research:
http://ciko.io/posts/cheap_usb_hdmi/
http://ciko.io/posts/cheap_usb_hdmi_2/
It uses test images or a color card and opencv, then compares it to input data.

Thanks again to Prez and that ciko.io author!

Cheers,
Chris

I received the AIXXCO yesterday that I ordered a long time ago. I confirm it supports DOS resolution well and is faster to change resolution than a monitor

christal87 wrote on 2021-07-27, 18:48:

Hi Prez, Everyone, […]
Show full quote

Prez wrote on 2020-08-14, 12:21:

Hi all ! […]
Show full quote

Hi all !

Just received another VGA2HDMI cheap device that works great under DOS mode 70Hz !
20200814_075848.jpg
20200814_075853.jpg

I will upload a video of Doom working on it.
It seems to be this one :
https://fr.aliexpress.com/item/32692452101.ht … .46f47ed3pf2rTs

Best regards
Philippe Dubois

Hi Prez,
Everyone,

I've just tried this cheap ass "AIXXCO brand" VGA to HDMI converter that Prez suggests. It's still available on Aliexpress as of Q2 2021 and yeah, it really works @70Hz in DOS.
It handles resolution changes quickly. Sometimes faster than my 2010s Fujitsu Siemens 4:3 TFT monitor and that "Foinnex brand" (also suggested by someone) that couldn't handle 70Hz at 320x200 or 700x400.
Keep in mind: it only supports resolutions at and over 800x600 in the specs. I've tested it on my 486 rig equipped with a VLB CL-GD5428. Stepping through the resolutions in CLUTIL some more specific resolutions+refresh rates show up slightly under- or overscanned (image border/sides are off the screen, mostly to the right). So It's not flawless, but works nice with most games for this price tag.
Now I'm opening it up and checking out what makes it tick. I hope it's not some "licensed" custom or not well known obsolete chinese ASIC. 😀
This is the URL I've bought it from a month ago: https://www.aliexpress.com/item/32692452101.html

There are two completely different units on sale at the link, could you clarify which one it is that you are recommending?

appiah4 wrote on 2021-07-29, 14:00:

christal87 wrote on 2021-07-27, 18:48:

Hi Prez, Everyone, […]
Show full quote

Prez wrote on 2020-08-14, 12:21:

Hi all ! […]
Show full quote

Hi all !

Just received another VGA2HDMI cheap device that works great under DOS mode 70Hz !
20200814_075848.jpg
20200814_075853.jpg

I will upload a video of Doom working on it.
It seems to be this one :
https://fr.aliexpress.com/item/32692452101.ht … .46f47ed3pf2rTs

Best regards
Philippe Dubois

Hi Prez,
Everyone,

I've just tried this cheap ass "AIXXCO brand" VGA to HDMI converter that Prez suggests. It's still available on Aliexpress as of Q2 2021 and yeah, it really works @70Hz in DOS.
It handles resolution changes quickly. Sometimes faster than my 2010s Fujitsu Siemens 4:3 TFT monitor and that "Foinnex brand" (also suggested by someone) that couldn't handle 70Hz at 320x200 or 700x400.
Keep in mind: it only supports resolutions at and over 800x600 in the specs. I've tested it on my 486 rig equipped with a VLB CL-GD5428. Stepping through the resolutions in CLUTIL some more specific resolutions+refresh rates show up slightly under- or overscanned (image border/sides are off the screen, mostly to the right). So It's not flawless, but works nice with most games for this price tag.
Now I'm opening it up and checking out what makes it tick. I hope it's not some "licensed" custom or not well known obsolete chinese ASIC. 😀
This is the URL I've bought it from a month ago: https://www.aliexpress.com/item/32692452101.html

There are two completely different units on sale at the link, could you clarify which one it is that you are recommending?

Pick the one with the cables built in. The option "Color: VGA TO HDMI Cable".

It uses a complete chinese IC solution called AG02-EX. There's an I2C EEPROM in there too. I suspect it contains the EDID.
The only datasheet I have found: http://mu.elecfans.net/201709/XR001%20VGA-VR1.0%20-.pdf
There are definately others with this chip, looking differently on the outside, like this one from the Czech Republic:
https://www.secomp.cz/konvertor-vga-audio-hdmi_d10033.html
The store specifically lists it as the same AG02-EX type.

christal87 wrote on 2021-07-29, 19:32:

Pick the one with the cables built in. The option "Color: VGA TO HDMI Cable". […]
Show full quote

appiah4 wrote on 2021-07-29, 14:00:

christal87 wrote on 2021-07-27, 18:48:

Hi Prez, Everyone, […]
Show full quote

Hi Prez,
Everyone,

I've just tried this cheap ass "AIXXCO brand" VGA to HDMI converter that Prez suggests. It's still available on Aliexpress as of Q2 2021 and yeah, it really works @70Hz in DOS.
It handles resolution changes quickly. Sometimes faster than my 2010s Fujitsu Siemens 4:3 TFT monitor and that "Foinnex brand" (also suggested by someone) that couldn't handle 70Hz at 320x200 or 700x400.
Keep in mind: it only supports resolutions at and over 800x600 in the specs. I've tested it on my 486 rig equipped with a VLB CL-GD5428. Stepping through the resolutions in CLUTIL some more specific resolutions+refresh rates show up slightly under- or overscanned (image border/sides are off the screen, mostly to the right). So It's not flawless, but works nice with most games for this price tag.
Now I'm opening it up and checking out what makes it tick. I hope it's not some "licensed" custom or not well known obsolete chinese ASIC. 😀
This is the URL I've bought it from a month ago: https://www.aliexpress.com/item/32692452101.html

There are two completely different units on sale at the link, could you clarify which one it is that you are recommending?

Pick the one with the cables built in. The option "Color: VGA TO HDMI Cable".

It uses a complete chinese IC solution called AG02-EX. There's an I2C EEPROM in there too. I suspect it contains the EDID.
The only datasheet I have found: http://mu.elecfans.net/201709/XR001%20VGA-VR1.0%20-.pdf
There are definately others with this chip, looking differently on the outside, like this one from the Czech Republic:
https://www.secomp.cz/konvertor-vga-audio-hdmi_d10033.html
The store specifically lists it as the same AG02-EX type.

Thanks, that helps a lot. I see plenty of cheap ass converters with AG02 chip in my region's web stores. So I wonder is AG02 also good or, it has to be AG02-EX to work for DOS mode?

crazii wrote on 2021-09-17, 19:52:

christal87 wrote on 2021-07-29, 19:32:

Pick the one with the cables built in. The option "Color: VGA TO HDMI Cable". […]
Show full quote

appiah4 wrote on 2021-07-29, 14:00:

There are two completely different units on sale at the link, could you clarify which one it is that you are recommending?

Pick the one with the cables built in. The option "Color: VGA TO HDMI Cable".

It uses a complete chinese IC solution called AG02-EX. There's an I2C EEPROM in there too. I suspect it contains the EDID.
The only datasheet I have found: http://mu.elecfans.net/201709/XR001%20VGA-VR1.0%20-.pdf
There are definately others with this chip, looking differently on the outside, like this one from the Czech Republic:
https://www.secomp.cz/konvertor-vga-audio-hdmi_d10033.html
The store specifically lists it as the same AG02-EX type.

Thanks, that helps a lot. I see plenty of cheap ass converters with AG02 chip in my region's web stores. So I wonder is AG02 also good or, it has to be AG02-EX to work for DOS mode?

The chip markings contain the -EX ending, but the datasheet only mentions this as an AG02. It could be the same. I'm not a 100% sure, you'll just have to experiment a bit.

christal87 wrote on 2021-09-18, 07:20:

crazii wrote on 2021-09-17, 19:52:

christal87 wrote on 2021-07-29, 19:32:

Pick the one with the cables built in. The option "Color: VGA TO HDMI Cable". […]
Show full quote

Pick the one with the cables built in. The option "Color: VGA TO HDMI Cable".

It uses a complete chinese IC solution called AG02-EX. There's an I2C EEPROM in there too. I suspect it contains the EDID.
The only datasheet I have found: http://mu.elecfans.net/201709/XR001%20VGA-VR1.0%20-.pdf
There are definately others with this chip, looking differently on the outside, like this one from the Czech Republic:
https://www.secomp.cz/konvertor-vga-audio-hdmi_d10033.html
The store specifically lists it as the same AG02-EX type.

Thanks, that helps a lot. I see plenty of cheap ass converters with AG02 chip in my region's web stores. So I wonder is AG02 also good or, it has to be AG02-EX to work for DOS mode?

The chip markings contain the -EX ending, but the datasheet only mentions this as an AG02. It could be the same. I'm not a 100% sure, you'll just have to experiment a bit.

Okay, here's my feedback: I ordered one converter labeled with "AG02"(not AG02-EX) yesterday while I replied this thread, and receive it today. Guess what, it works! I am very much satisfied. Thanks dude!

crazii wrote on 2021-09-18, 14:15:

christal87 wrote on 2021-09-18, 07:20:

crazii wrote on 2021-09-17, 19:52:

Thanks, that helps a lot. I see plenty of cheap ass converters with AG02 chip in my region's web stores. So I wonder is AG02 also good or, it has to be AG02-EX to work for DOS mode?

The chip markings contain the -EX ending, but the datasheet only mentions this as an AG02. It could be the same. I'm not a 100% sure, you'll just have to experiment a bit.

Okay, here's my feedback: I ordered one converter labeled with "AG02"(not AG02-EX) yesterday while I replied this thread, and receive it today. Guess what, it works! I am very much satisfied. Thanks dude!

I'm happy it works! I've just tried to find some common characteristic that describes the Aixxco adapter that Prez found before me.

Hello,

I picked up that AIXXCO adapter and it arrived today, have some weird results to share.

I use this for my capture card: https://www.amazon.ca/gp/product/B0813JPLNT/
KVM: https://www.amazon.com/Rosewill-RKV-2P-Deskto … o/dp/B004E2I3YK (from ages ago, works amazingly well btw)
Relevant DOS rig specs: P200MMX, Cardex S3 Trio64 V2/DX 4MB + Diamond Monster3D 4MB, DOS 6.22.
Relevant Win98 rig specs: P4 3.0C, AIW 9800 Pro, Win98SE and WinXP dual boot using XFDISK.
Secondary VGA Monitor is an Asus VP248 using HDMI pass through from the capture card

On the P200 for DOS and simple DOS games, it works and displays decently well on the secondary monitor. No over scan. Off centre by a little bit to the right (2-3 pixels).
Capture card has over scan issues with it and off centre to the left.
ASUS monitor reports displayed resolution at the DOS prompt as 640x416 @ 70hz. "Standard VGA" DOS games like Raptor Call of the Shadows and Duke Nukem 2 are displayed at that resolution as well. Not sure where this resolution comes from but all 80x24 character DOS screens are showing at this res.
VESA games like Duke3D at 800x600 display great on both screens. Off centre to the right by 2-3 pixels, no over scan.
Glide games like Descent II run at 640x480 have no over scan issues but it's off centre to the right on both screens.
Nothing changes if I connect the converter directly to the voodoo, the VGA, or the KVM.

On the P4 in Win98 desktop, there is no over scan anywhere.
At 800x600 on the desktop, it's off to the right considerably on capture card (by at least 20+ pixels). Monitor it's off to the right by like 2-3 pixels
At 1024x768 same issue as above.
At 1280x1024 solves the right shift (2-3 pixels to the right still) but it looks terrible on capture card. Looks great on the monitor.

I connected the KVM directly to the ASUS monitor's VGA in and it shows the proper resolution of 720x400 @ 70hz in DOS but obviously no ability to capture.

This leads me to believe that my capture card is just terrible for 720x400. But here's the strange part. On the P4 at the OS select, resolution displayed is 640x416 @ 70hz so it's the same as the DOS rig. But there's no over scan glitching on either displays. Capture card is shifted to the left a bit but the picture itself looks great.

Would this be an issue with my Trio or is there some kind of setting in OBS that I can use to mimic the P4's result on the DOS rig? I have to issue a debug command on the DOS rig in autoexec to get it to not display blacks too brightly. If it's truly my capture card, any suggestions of good ones that take HDMI in (I have other devices connected to a HDMI switch and would like to be able to use them as well)?

Appreciate any advice or insight. 😀

gen_angry wrote on 2021-09-24, 20:37:

Hello, […]
Show full quote

Hello,

I picked up that AIXXCO adapter and it arrived today, have some weird results to share.

I use this for my capture card: https://www.amazon.ca/gp/product/B0813JPLNT/
KVM: https://www.amazon.com/Rosewill-RKV-2P-Deskto … o/dp/B004E2I3YK (from ages ago, works amazingly well btw)
Relevant DOS rig specs: P200MMX, Cardex S3 Trio64 V2/DX 4MB + Diamond Monster3D 4MB, DOS 6.22.
Relevant Win98 rig specs: P4 3.0C, AIW 9800 Pro, Win98SE and WinXP dual boot using XFDISK.
Secondary VGA Monitor is an Asus VP248 using HDMI pass through from the capture card

On the P200 for DOS and simple DOS games, it works and displays decently well on the secondary monitor. No over scan. Off centre by a little bit to the right (2-3 pixels).
Capture card has over scan issues with it and off centre to the left.
ASUS monitor reports displayed resolution at the DOS prompt as 640x416 @ 70hz. "Standard VGA" DOS games like Raptor Call of the Shadows and Duke Nukem 2 are displayed at that resolution as well. Not sure where this resolution comes from but all 80x24 character DOS screens are showing at this res.
VESA games like Duke3D at 800x600 display great on both screens. Off centre to the right by 2-3 pixels, no over scan.
Glide games like Descent II run at 640x480 have no over scan issues but it's off centre to the right on both screens.
Nothing changes if I connect the converter directly to the voodoo, the VGA, or the KVM.

On the P4 in Win98 desktop, there is no over scan anywhere.
At 800x600 on the desktop, it's off to the right considerably on capture card (by at least 20+ pixels). Monitor it's off to the right by like 2-3 pixels
At 1024x768 same issue as above.
At 1280x1024 solves the right shift (2-3 pixels to the right still) but it looks terrible on capture card. Looks great on the monitor.

I connected the KVM directly to the ASUS monitor's VGA in and it shows the proper resolution of 720x400 @ 70hz in DOS but obviously no ability to capture.

This leads me to believe that my capture card is just terrible for 720x400. But here's the strange part. On the P4 at the OS select, resolution displayed is 640x416 @ 70hz so it's the same as the DOS rig. But there's no over scan glitching on either displays. Capture card is shifted to the left a bit but the picture itself looks great.

Would this be an issue with my Trio or is there some kind of setting in OBS that I can use to mimic the P4's result on the DOS rig? I have to issue a debug command on the DOS rig in autoexec to get it to not display blacks too brightly. If it's truly my capture card, any suggestions of good ones that take HDMI in (I have other devices connected to a HDMI switch and would like to be able to use them as well)?

Appreciate any advice or insight. 😀

Yeah, that passthrough might stir things up. I haven't used any HDMI passthrough capable devices, because I was not really sure it would work as expected. No Voodoo card test yet either. I'm planning to record some of my gameplays in the winter. At that point I'll have more experience with the capture setup. I've did my resolution and refresh rate tests with a simple chinese USB capture dongle. I think it's a generic type widely available that uses a webcam sensor chipset and an HDMI transceiver internally. I only hook up the Aixxco to the capture card and use a "Y-cable" VGA splitter to feed the signal to it. So the analog VGA signal splits directly into my old 4:3 Fujitsu TFT screen's DSUB-in on one end and the Aixxco on the other. BTW: my capture card's factory image settings are crap, so I had to tweak them to look right. (Brightness, contrast, saturation, gamma, hue, etc.)

Capture:https://www.aliexpress.com/item/1005001880861192.html
Splitter:https://www.aliexpress.com/item/4000581343084.html

crazii wrote on 2021-09-18, 14:15:

christal87 wrote on 2021-09-18, 07:20:

crazii wrote on 2021-09-17, 19:52:

Thanks, that helps a lot. I see plenty of cheap ass converters with AG02 chip in my region's web stores. So I wonder is AG02 also good or, it has to be AG02-EX to work for DOS mode?

The chip markings contain the -EX ending, but the datasheet only mentions this as an AG02. It could be the same. I'm not a 100% sure, you'll just have to experiment a bit.

Okay, here's my feedback: I ordered one converter labeled with "AG02"(not AG02-EX) yesterday while I replied this thread, and receive it today. Guess what, it works! I am very much satisfied. Thanks dude!

Which one did you buy?

matti157 wrote on 2021-09-29, 13:09:

crazii wrote on 2021-09-18, 14:15:

christal87 wrote on 2021-09-18, 07:20:

The chip markings contain the -EX ending, but the datasheet only mentions this as an AG02. It could be the same. I'm not a 100% sure, you'll just have to experiment a bit.

Okay, here's my feedback: I ordered one converter labeled with "AG02"(not AG02-EX) yesterday while I replied this thread, and receive it today. Guess what, it works! I am very much satisfied. Thanks dude!

Which one did you buy?

I bought a black colored SAMZHE converter with USB power supply and an audio line, model VH2018. Not sure it available on Amazon. I will not recommend this one since its too expensive on Joybuy. (costs US$179.46 at the time I reply you. WTF?) I bought it on Joybuy China and it cost me CNY 59, that's about US$10.
Cons:
1. There's some wave-ish noises noticeable on win98 startup logo and initial desktop but will be stabilized through time and that is acceptable.
2. The top-right corner of the image (part of the 'close' button of a maximized window) is off screen, but I'm able to fix that using win98's ATI graphics utility to move the whole image left a bit.

It's Tested with a HP T5700 with ATI RAGE XL on a EPSON projector. I uses an older win98 driver not the latest WinME one because the WinME driver reports missing file on installation, still it can work on win98, but it will not save my settings on next system start.
I also tested a UNITEK V112A (V112ABK) later. its AG02 and acts the same as SAMZHE VH2018, and it costs the same too.

Hey everyone, new to this forum (first post!) and wanted to chime in on my experience in this matter.

I have an Alienware AW3418DW that I use for gaming on my nice gaming PC. I also have a 4-way HDMI/USB KVM that I use to toggle between my nice recent gaming PC, my work laptop, my retro Windows XP pc (2002-2003 parts) and my retro Windows 98 pc (1997 IBM Aptiva with a Matrox G450).

Basically I have been trying for ages to get both DOS and Windows to output to the monitor properly. I've finally been successful.

I have tried many crappy VGA-HDMI adaptors off of Amazon and also tried the AIXXCO brand mentioned earlier. None of these work in DOS/BIOS at all since my monitor cannot support 70hz. In fact I found another Amazon brand VGA-HDMI adaptor performed better than the AIXXCO because the AIXXCO EDID will claim to support 70hz - so at least this worked in Windows. Even though my monitor goes up to 120hz it doesn't support 70hz and definitely doesn't support DOS resolutions. In fact it's just very finicky about everything.

DVI-HDMI on the Matrox G450 doesn't work, probably also because of the poor EDID implementation on my monitor. (Which is disappointing because it was very expensive, but I'm probably the first person to try to plug a 24 year old computer into it.)

So I saw another thread on shmups where someone recommended the Extron RGB-HDMI 300-A. I picked one of these off eBay for cheap (~$40). The Extron is a very nice unit and really built just for this purpose. It outputs 1920x1080 which is the best non-native resolution my monitor can accept.

The one issue I had was again EDID. The Extron will pass this through HDMI by default which of course led to a broken 640x480 display in Windows. The Extron can also emulate EDID if you disable HDMI data, but the emulated 1920x1080 EDID wasn't honored by Windows - the best I could do was 1024x768. So I finally severed the EDID pins (#15 and #11) on my VGA cable and finally Windows stopped caring about what my monitor "supported". I was able to set a 1920x1080 resolution in Windows and now the whole thing works great.

Now you might be thinking, how did I get my keyboard and mouse working in DOS. Like I said I have a USB+HDMI KVM. The KVM acts as a USB hub. This computer does have USB ports, but the BIOS does not support HID devices, and I doubt DOS would as well. So I used and Arduino with a USB Host shield to connect to my keyboard and mouse. I used the ps2dev library to emulate the PS2 keyboard. I tried doing this with the mouse but was unsuccessful. So I bought a TTL to RS232 adapter and use that to emulate a serial mouse. My little custom Arduino adapter isn't that reliable though, sometimes Windows doesn't pick up the mouse on boot and I have to restart.

Overall I'm really happy with this whole setup, although 1080p is a little blurry. I have a Radeon 7000 and a GeForce 5200 on the way. I will try using a DVI connection with these to see if I get a better picture than with the Extron. But at least the Matrox G450 is a "period correct" piece of hardware for what it's worth, so I may keep it.

TL;DR: If you want a foolproof solution, get the Extron RGB-HDMI 300 A

I also struggle with this 70Hz 4:3 DOS Problem for a while.
So i also like to share my results with you.

So first the Hardware i use. My GPU is a Elsa Synergy 2 AGP (Riva TNT2).
My TFT is a Asus PA248QV (1920x1200 70Hz).
I tryed to combine the OSSC with a framemeister. The results are :

DVI Mode 1600x1200 4:3 @60Hz = OK
HDMI Mode 1280x800 (fixed) 16:10 @70Hz = OK

I tryed different option with the framemeister like sync mode off and so far but with DVI mode anything is limited to 60Hz even my Monitor can handle 70Hz.
Well both options looks really nice with the framemeister. But its not the perfect result 4:3 @70Hz on DOS.
Soon as i switch to hdmi mode i cant change the ratio any more.
I also tryed a XRGB-3 but the VGA output is really bad..

Jackhead wrote on 2021-11-03, 15:38:

I also struggle with this 70Hz 4:3 DOS Problem for a while. So i also like to share my results with you. […]
Show full quote

I also struggle with this 70Hz 4:3 DOS Problem for a while.
So i also like to share my results with you.

So first the Hardware i use. My GPU is a Elsa Synergy 2 AGP (Riva TNT2).
My TFT is a Asus PA248QV (1920x1200 70Hz).
I tryed to combine the OSSC with a framemeister. The results are :

DVI Mode 1600x1200 4:3 @60Hz = OK
HDMI Mode 1280x800 (fixed) 16:10 @70Hz = OK

I tryed different option with the framemeister like sync mode off and so far but with DVI mode anything is limited to 60Hz even my Monitor can handle 70Hz.
Well both options looks really nice with the framemeister. But its not the perfect result 4:3 @70Hz on DOS.
Soon as i switch to hdmi mode i cant change the ratio any more.
I also tryed a XRGB-3 but the VGA output is really bad..

The monitor is unfortunately the issue here . See Re: Purchasing a 4:3 LCD for DOS/DOSBOX/MISTER/OSSC games?

darry wrote on 2020-06-07, 06:07:

So, I now have an OSSC . […]
Show full quote

So, I now have an OSSC .

After some phase adjustments, it works great in all pass-through resolutions, that is anything with more than 400 lines of vertical resolution, up to and including 1600x1200 at 60Hz .
720x400@70Hz and 640x400@70Hz display fine in pass-through mode and with line2x, but are stretched by the monitor .

I then tried 720x400@70Hz and 640x400@70Hz with the line3x option and found that they were glitchy on my OSSC unit at least (on screen shimmering) .
I understand that the 1600x1200 @70Hz mode that is being output is out of spec (189MHz) and that the TMDS in the OSSC likely does not like it .

What I do not understand is why it was not possible to implement 1600x1200@70Hz with reduced blanking to fit under 162MHz and avoid over-specing the TMDS . Is this due to the line-multiplication only implementation of OSSC and thus lack of a frame buffer ?

Another thing I do not understand is why, in line3x mode, does horizontal sampling need to be set to 2000 lines? The actual horizontal resolution of the source does not change when line3x is enabled, so why is horizontal sampling not set to 900 or 800 total lines (including inactive lines for 720x400@70Hz and 640x400@70Hz ), like in line 2x or pass-through mode ?

Sorry if these are dumb questions and if this is not the best place to ask, but there does not seem to be a lot of info about using 400-line DOS modes with an OSSC , or at least not that I have found .

Any insight, suggestions or references to good beginner docs on using an OSSC, especiallly with DOS VGA modes, would be greatly appreciated .

Hey darry, I stumbled upon your posts here (thanks!) and decided to get my OSSC working between my DOS gaming PC and a 4:3 Dell LCD (PC connected to VGA port on OSSC, OSSC connected to LCD using an HDMI>DVI cable). I finally got it working, and it looks fantastic!! One thing I'm having an issue with is the LCD losing the signal when switching from the DOS prompt to a game (it maintains the signal from game to DOS prompt). The OSSC seems like it is not dropping sync. My workaround now is to just switch inputs on the OSSC back and forth, and the LCD picks right up. Did you encounter this at all with your setup? If so, did you find any settings that helped?

newtmonkey wrote on 2021-12-22, 14:43:

darry wrote on 2020-06-07, 06:07:

So, I now have an OSSC . […]
Show full quote

So, I now have an OSSC .

After some phase adjustments, it works great in all pass-through resolutions, that is anything with more than 400 lines of vertical resolution, up to and including 1600x1200 at 60Hz .
720x400@70Hz and 640x400@70Hz display fine in pass-through mode and with line2x, but are stretched by the monitor .

I then tried 720x400@70Hz and 640x400@70Hz with the line3x option and found that they were glitchy on my OSSC unit at least (on screen shimmering) .
I understand that the 1600x1200 @70Hz mode that is being output is out of spec (189MHz) and that the TMDS in the OSSC likely does not like it .

What I do not understand is why it was not possible to implement 1600x1200@70Hz with reduced blanking to fit under 162MHz and avoid over-specing the TMDS . Is this due to the line-multiplication only implementation of OSSC and thus lack of a frame buffer ?

Another thing I do not understand is why, in line3x mode, does horizontal sampling need to be set to 2000 lines? The actual horizontal resolution of the source does not change when line3x is enabled, so why is horizontal sampling not set to 900 or 800 total lines (including inactive lines for 720x400@70Hz and 640x400@70Hz ), like in line 2x or pass-through mode ?

Sorry if these are dumb questions and if this is not the best place to ask, but there does not seem to be a lot of info about using 400-line DOS modes with an OSSC , or at least not that I have found .

Any insight, suggestions or references to good beginner docs on using an OSSC, especiallly with DOS VGA modes, would be greatly appreciated .

Hey darry, I stumbled upon your posts here (thanks!) and decided to get my OSSC working between my DOS gaming PC and a 4:3 Dell LCD (PC connected to VGA port on OSSC, OSSC connected to LCD using an HDMI>DVI cable). I finally got it working, and it looks fantastic!! One thing I'm having an issue with is the LCD losing the signal when switching from the DOS prompt to a game (it maintains the signal from game to DOS prompt). The OSSC seems like it is not dropping sync. My workaround now is to just switch inputs on the OSSC back and forth, and the LCD picks right up. Did you encounter this at all with your setup? If so, did you find any settings that helped?

Hi,

I have not encountered such issues with either my "bootleg" OSSC or my genuine one . Are you sure it's the OSSC that's having an issue and not the monitor ? How do "fix" the issue (toggle input on the monitor, toggle input on OSSC, power cycle OSSC, power cycle monitor) ?

Some devices (monitors and OSSC, AFAICR), by either switch input when they think signal has been lost too long or try to auto-cycle through inputs to find a signal. This may be what's happening. See if you can disable this behavior and whether it resolves the issue .

darry wrote on 2021-12-23, 03:32:

Hi,

I have not encountered such issues with either my "bootleg" OSSC or my genuine one . Are you sure it's the OSSC that's having an issue and not the monitor ? How do "fix" the issue (toggle input on the monitor, toggle input on OSSC, power cycle OSSC, power cycle monitor) ?

Some devices (monitors and OSSC, AFAICR), by either switch input when they think signal has been lost too long or try to auto-cycle through inputs to find a signal. This may be what's happening. See if you can disable this behavior and whether it resolves the issue .

Thanks for replying!
I am pretty sure it's the monitor, as the OSSC seems to maintain sync throughout. I can get around the issue by either power cycling the OSSC, or switching inputs on the OSSC (either remote or using the physical button on the OSSC). Switching inputs on the monitor (or power cycling it) doesn't help. The monitor doesn't seem to have any setting to enable/disable auto-cycle, but it also doesn't appear to be doing that anyway.

I have another 4:3 LCD I can test, so I might do that on the weekend. [EDIT: same result on the other monitor]
In the worst case scenario, using the physical button on the OSSC to switch inputs isn't too big a deal, and is just a minor hassle for such improved image quality.

It's possible this is an issue with using an HDMI-DVI cable from the OSSC to the monitor. I might see if I can find an HDMI-VGA converter to test that. There's a list of "officially" approved converters for use with the OSSC, but they are either very expensive (hundreds of dollars) or no longer available.

Bad results with cheap VGA to HDMI adapters, including one that looked like the AIXXCO brand one:

I bought a "Cuxnoo" brand VGA to HDMI adapter from the Amazon Australia site at https://www.amazon.com.au/gp/product/B08SK5JFKP because it explicitly listed "720x400@70Hz" in the description, but it doesn't actually seem to support this. In fact although the product looks very different from the white box "Mini VGA2HDMI" described in https://goughlui.com/2019/02/02/quick-teardow … hdmi-converter/, it was packaged in the same way and the manual is almost identical apart from some text being in bold, text moved around in the diagram, and a box in the diagram. Notably the manual doesn't mention 720x400, and the diagram doesn't even illustrate this particular product.

When I look at the same product on the US Amazon site at https://www.amazon.com/gp/product/B08SK5JFKP its description is quite different and doesn't have any list of resolutions, so I suppose I should take some lessons away from this about how much to trust Amazon product descriptions.

I requested a refund from Amazon, and then had to ask them for assistance because their instructions were unclear, at which point they just gave me a refund immediately and said I could keep the item, which seems odd. However they seem to have unfortunately deleted my negative review of the item (edit: or maybe it just hasn't appeared yet?). I'll mention the other issues I had with this converter here then, which is that I had much the same experience as the reviewer who said "There were so many waves on the display that people were lining up to surf them", and also that the retention screws are permanently protruding a little so you have to screw them in to get a decent connection (which is very difficult) and it's not possible to plug it properly in to a laptop which has no holes for the screws unless you use a VGA extension cable or something.

I opened it up and it contains a Macro Silicon MS9288C chip, so I suppose a slightly newer version of the one from that blog post I linked.

Here is what the Linux xrandr command says about the resolutions and frequencies supported by this adapter:

1VGA-1 connected primary 1680x1050+0+0 (normal left inverted right x axis y axis) 0mm x 0mm
2   1024x768      60.04    60.00
3   960x720       60.00
4   928x696       60.05
5   896x672       60.01
6   1024x576      59.95    59.96    59.90    59.82
7   960x600       59.93    60.00
8   960x540       59.96    59.99    59.63    59.82
9   800x600       60.00    60.32    56.25
10   840x525       60.01    59.88
11   864x486       59.92    59.57
12   848x480       60.00
13   700x525       59.98
14   800x450       59.95    59.82
15   640x512       60.02
16   700x450       59.96    59.88
17   640x480       60.00    59.94
18   720x405       59.51    58.99
19   684x384       59.88    59.85
20   640x400       59.88    59.98
21   640x360       59.86    59.83    59.84    59.32
22   512x384       60.00
23   512x288       60.00    59.92
24   480x270       59.63    59.82
25   400x300       60.32    56.34
26   432x243       59.92    59.57
27   320x240       60.05
28   360x202       59.51    59.13
29   320x180       59.84    59.32
30  1680x1050 (0x47) 146.250MHz -HSync +VSync
31        h: width  1680 start 1784 end 1960 total 2240 skew    0 clock  65.29KHz
32        v: height 1050 start 1053 end 1059 total 1089           clock  59.95Hz

720x405 sounds like it could be close enough, but notice that there is nothing higher than about 60.05Hz there.

I also bought an unbranded VGA to HDMI adapter from eBay which looked identical to the AIXXCO brand one - it even seemed like one of the pictures in the listing was based on the same photograph - but when it arrived it didn't look the same (the lettering was purple instead of gold), it had yet another subtly different copy of the same manual, and also didn't seem to support 720x400@70Hz.

I should probably just try the AIXXCO one from AliExpress next!

christal87 wrote on 2021-07-27, 18:48:

Note on some "el cheapo" webcam based USB video class (UVC) HDMI capture devices: [...] most of these dongles want to look like USB3, but most are only 2.0 High Speed (HS). This means that uncompressed raw video (e.g. YUYV) will have a limitation either on framerate or maximum resolution, whichever you choose (game capture at 5FPS is not great). You simply can't dunk down like 2.1+MPixels (1920x1080@30...60Hz uncompressed on USB2. It's worth looking for true USB3 capture dongles in the future to avoid this huge limitation.

I also bought a "TenYua" brand "USB 3.0 HDMI Video Grabber" from Amazon - https://www.amazon.com.au/gp/product/B089YMY71Y - since I understood that I needed USB 3 to get good frame rates, but it turned out that it could only capture 640x480 YUYV at 30 FPS, and higher resolutions were much lower frame rates like 5 FPS. On checking lsusb -v in Linux I can see it's really only USB 2.0. I suppose I could probably get my money back on this one too but I'm not sure if I could find a better one that doesn't cost a lot more. Perhaps I could have found a cheaper one that works just as well but doesn't pretend to be USB 3?

Are there any hints that a device isn't really USB 3? This particular device requires a USB A to A cable. I've never seen a USB device/gadget with a USB A socket before, this seems strange to me. I wonder if a blue USB A port is just the cheapest way to make your device look like it's USB 3 when it's not really?