What VGA cards are you using? If it's Trident, Cirrus Logic and a couple of others, you can change the output to 15khz in DOS with a TSR. Then all you have to do is make a synch combiner and feed the RGB to the RGB.

If it's got later 3D cards, some of those may have TV output utilities you can use through windows and force 15khz... or not. Some of them have real TV out, or the VO in VIVO, which isn't bad through composite on a 1084.

Other than those solutions is when you get into the magic boxes.... here's the manual of a cheapy one I've got hanging around, which I haven't really "got into" heavily yet, as it was a "oooh, might need that sometime" thrift pickup... that should give you some idea of what they do...
https://www.manualslib.com/manual/691296/Kwor … Box.html#manual

^^^^^^^

https://www.qsl.net/dh1dm/tv_50hz_svga/
http://web.archive.org/web/20041207011319/htt … s/vga2rgbs.html

Hi Boggit, you can easily use a VGA-Composite converter here.

The converter takes a VGA signal from your VGA card and supports output to NTSC/PAL and 50 Hz/ 60Hz, as you wish.

This is probably the most straightforward solution if you want to use a Commodore 1084 monitor with a Commodore PC that has a VGA card installed.

You can have full EGA and VGA resolution, with a lot of colours.
If you have an 8-Bit, 256 KB Paradise PVGA1A, for example, you can have 640x400 256c in Windows 2.03 or 3.0. Or just 640x480 16c, normal VGA.

With an upgrade to 1MB of Video RAM, same basic VGA card can do 640x480 256c no problem.
That's okay for an SVGA chess game such as Grandmaster Chess. Though plain VGA is still okay for an XT.

Edit: The mere downside is flickering. These converters do normal video with interlacing, after all.

Edit: If you build a special cable and use a DOS TSR, you can output 320x200 256c at ~15 KHz without interlacing. This has less flicker than using a converter box.
The 200 line mode is interesting for those mode 13h games, which use MCGA.

Realistically speaking, though, VGA cards never did output them that way. They always used 400 lines at ~31 KHz, so it was 320x400 or 640x400 to the VGA monitor.

Also, even if you add the TSR to autoexec.bat, the TSR isn't being loaded until the PC has fully booted.
You won't see the BIOS text if you power on the PC first time, the VGA timings will confuse -if not damage- the 1084S monitor.
So in practice the 1084S can be turned on only after the TSR has been run.

Edit: One of my converters is an AVerKey Pro. Have to check the others..

BitWrangler wrote on 2024-11-25, 21:11:

What VGA cards are you using? If it's Trident, Cirrus Logic and a couple of others, you can change the output to 15khz in DOS with a TSR. Then all you have to do is make a synch combiner and feed the RGB to the RGB.

Thanks a lot for your input!

I forgot to add in my initial post that I am not looking for a solution that necessitates me building and/or soldering anything, as I have no relevant skillset, equipment or time.

BitWrangler wrote on 2024-11-25, 21:11:

Other than those solutions is when you get into the magic boxes.... here's the manual of a cheapy one I've got hanging around, which I haven't really "got into" heavily yet, as it was a "oooh, might need that sometime" thrift pickup... that should give you some idea of what they do...
https://www.manualslib.com/manual/691296/Kwor … Box.html#manual

Thanks! I will look into that!

You can buy a readymade GBS-Control these days. Probably still the best option for you. Using the VGATV TSR as mentioned is a great tool to play certain games in "native" 15kHz, but it is too finicky of a solution for me to recommend it as a primary display

Jo22 wrote on 2024-11-25, 21:18:

Also, even if you add the TSR to autoexec.bat, the TSR isn't being loaded until the PC has fully booted.
You won't see the BIOS text if you power on the PC first time, the VGA timings will confuse -if not damage- the 1084S monitor.
So in practice the 1084S can be turned on only after the TSR has been run.

Is it really true that it would damage the monitor if it's turned on before the TSR is loaded?

I'm thinking of a similar setup, but with an RGB SCART TV, but if I have to be careful about the sequence in which I should switch everything on, with the possibility of damaging the screen if I time it wrong, it makes it a much less attractive setup.

A more idiot-proof way of getting 15KHz RGB out of a PC (without down-conversion to S-Video or composite) would be great.

digger wrote on 2024-11-25, 23:19:

Is it really true that it would damage the monitor if it's turned on before the TSR is loaded? […]
Show full quote

Jo22 wrote on 2024-11-25, 21:18:

Also, even if you add the TSR to autoexec.bat, the TSR isn't being loaded until the PC has fully booted.
You won't see the BIOS text if you power on the PC first time, the VGA timings will confuse -if not damage- the 1084S monitor.
So in practice the 1084S can be turned on only after the TSR has been run.

Is it really true that it would damage the monitor if it's turned on before the TSR is loaded?

I'm thinking of a similar setup, but with an RGB SCART TV, but if I have to be careful about the sequence in which I should switch everything on, with the possibility of damaging the screen if I time it wrong, it makes it a much less attractive setup.

A more idiot-proof way of getting 15KHz RGB out of a PC (without down-conversion to S-Video or composite) would be great.

The ideotproof way is to buy an old Averkey Micro

It never sends out anything other than 15khz over composite, svideo and RGB sync .
You can center and overscan/underscan to your hearts content

rmay635703 wrote on 2024-11-26, 06:31:

The ideotproof way is to buy an old Averkey Micro

It never sends out anything other than 15khz over composite, svideo and RGB sync .
You can center and overscan/underscan to your hearts content

Excellent!

I actually have an AVerMedia AVerTV Box9, but that one only has S-Video etc for input, not for output.

I've looked at AVerKey iMicro and it looks promising, but on the features list, it seems to say that the lowest possible horizontal frequency is 31.5khz, and what I need for 1084S-P2 is around 15khz, no? Am I misunderstanding something?

maxtherabbit wrote on 2024-11-25, 22:05:

You can buy a readymade GBS-Control these days. Probably still the best option for you. Using the VGATV TSR as mentioned is a great tool to play certain games in "native" 15kHz, but it is too finicky of a solution for me to recommend it as a primary display

Great! I've looked at it on Amazon and it is quite pricey, but if it is the only device available that will give me a good, high quality VGA picture on my Commodore 1084 screen, then it might be worth it. Exactly what would be the setup for getting this to work for my use case? The GBS-Control seems to have so many different functions and options, and I'm not sure what's applicable for me.

Jo22 wrote on 2024-11-25, 21:18:

Hi Boggit, you can easily use a VGA-Composite converter here.

The converter takes a VGA signal from your VGA card and supports output to NTSC/PAL and 50 Hz/ 60Hz, as you wish.

This is probably the most straightforward solution if you want to use a Commodore 1084 monitor with a Commodore PC that has a VGA card installed.

Good to know! I was hoping to get something better than composite output, but maybe I will have to live with that.

The 1084 would not be damaged by feeding it 31kHz. It simply wouldn't sync to it

maxtherabbit wrote on 2024-11-26, 13:39:

The 1084 would not be damaged by feeding it 31kHz. It simply wouldn't sync to it

Okay, good to know!

maxtherabbit wrote on 2024-11-26, 13:39:

The 1084 would not be damaged by feeding it 31kHz. It simply wouldn't sync to it

And he is referring to the averkey Imicro input frequency not the fixed 15khz output.

A custom cable is a given but otherwise should be a pretty easy build.

If he wants to send EGA like signals 20-24khz into a 1084 there are better ways.

rmay635703 wrote on 2024-11-26, 19:08:

And he is referring to the averkey Imicro input frequency not the fixed 15khz output.

A custom cable is a given but otherwise should be a pretty easy build.

Sorry, am I the "he" in this? Or max?

So I would need a custom cable in order to go VGA->1084s? What sort of cable?

Yeah, I did some searching and apparently the SCART adapter doesn't come out of the box with the AVerKey iMicro, but is apparently an optional accessory. It is also implied in the manual that there is a separate PAL version of the iMicro, that the cable would come with.

I certainly hope that the NTSC version outputs RGB and can be adapted to SCART as well. The TV that I would want to hook it up to has RGB SCART, but also supports 60Hz NTSC.

By the way, the AVerKey iMicro can indeed be found for cheap on eBay by many a seller, but all of the sellers are in the US, so I'd be paying shipping and taxes that would cost me three times the cost of the device.

It might still be worth getting one, though.

Any idea on how to DIY a SCART adapter cable for the iMicro? The RGB port isn't clearly shown in the manual. Is it just a 15-pin VGA port carrying a 15kHz RGB signal?

Hey, I realized that the Tseng ET3000AX has both ttl/rgb and vga ports. If I were to connect it to an EGA monitor (I have one of those as well), would that only give me EGA graphics mode at best?

Reading here, that parts seems to be a little unclear.

EDIT: Nope, that is a no go. 16 color max on an EGA screen.

boggit wrote on 2024-11-28, 07:32:

Hey, I realized that the Tseng ET3000AX has both ttl/rgb and vga ports. If I were to connect it to an EGA monitor (I have one of those as well), would that only give me EGA graphics mode at best?

Reading here, that parts seems to be a little unclear.

It depends. Generally speaking, early VGA cards were based on EGA cards with extended EGA resolutions.
At principle, the only thing new was support for higher colour depths and the use of an external RAM DAC chip (ET3000 also had hardware zoom feature etc).

Things like 800x600 16c or 640x480 16c were available with Super EGA graphics cards - in tandem with "multi sync" monitors.

When VGA was on the horizon in 1987, many EGA cards had the ability to aditionally emulate VGA BIOS modes 11h (640x480 mono) and 12h (640x480 16c).
Using EGA/VGA standard palette, of course. No 256c mode support, no mode 13h/MCGA.

Cards which supported this were the ATI EGA Wonder series, for example.
They could do this with an corresponding monitor.

As far as EGA monitors go, the CGA and EGA video modes are available.
Hercules, too, maybe if a supplied mode utility supports it.

I don’t know of any EGA/VGA card which does use interlacing on an EGA monitor to support higher resolutions.
It was rather opposite. Limited, flickering EGA support on CGA monitors (to simulate 640x350 16c by using itnerlacing).

PS: A true EGA monitor can display 64 colours via digital TTL port. However, EGA doesn't have a dedicated 64c mode.
It rather has several fixed palettes and can display 16c at once only.
Some games like that Iron Man racing game or that Snoopy game do use 64 colour mode.
They switch palettes on the fly, as needed, as far as I understand.

Has anyone here tried using an AverKey solution to run VGA on an RGB monitor? How good was the quality?

Jo22 wrote on 2024-11-28, 09:31:

I don’t know of any EGA/VGA card which does use interlacing on an EGA monitor to support higher resolutions. It was rather oppos […]
Show full quote

I don’t know of any EGA/VGA card which does use interlacing on an EGA monitor to support higher resolutions.
It was rather opposite. Limited, flickering EGA support on CGA monitors (to simulate 640x350 16c by using itnerlacing).

PS: A true EGA monitor can display 64 colours via digital TTL port. However, EGA doesn't have a dedicated 64c mode.
It rather has several fixed palettes and can display 16c at once only.
Some games like that Iron Man racing game or that Snoopy game do use 64 colour mode.
They switch palettes on the fly, as needed, as far as I understand.

Didn't such advanced EGA cards also use PWM to support 64 colors on CGA monitors as well?

boggit wrote on 2024-11-28, 09:45:

Has anyone here tried using an AverKey solution to run VGA on an RGB monitor? How good was the quality?

To be honest, I didn't notice a visual difference between RGB and Composite.
But this was a SCART TV with a PAL decoder.

The screenshots can be seen here: Re: MCGA Games (PC/DOS) - LCD vs CRT
I've used SCART @60 Hz mainly, but PAL 60 through Composite didn't look any different to me.
This monitor's CRT screen mask was too blurry/low-res for it to be visually noticeable.

(Quick explanation. I've configured an 60 Hz output on the converter box because common VGA resolution is 640x480 60 Hz which is close to American TV standard;
if I would use 50 Hz the picture would be squashed/letterboxed due to European TV standard being of higher resolution - ca. 720x576 50 Hz.
Video game consoles like NES or Sega Genesis have similar problems with PAL borders.
On an analogue video monitor such as an Commodore 1702 things can be compensated by using h-size and v-size knobs. On an ordinary SCART TV, this option doesn'texist sadly.)

For NTSC users with an RGB-capable video monitor the result might be different.
NTSC via Composite can has a lot of colour bleed, artifacts and rainbow banding effects, making RGB a better choice.

Another question: how well do those DOS TSRs that force 15kHz mode work with more modern VGA cards and chipsets?

Has anybody tried those TSRs on more recent hardware, by any chance?