what a nice thread!
I remember I have these old pics from when I tried exactly that: MDA monitor + EGA WONDER 800 (the pure ega version)

keropi wrote on 2022-04-30, 16:20:

what a nice thread!
I remember I have these old pics from when I tried exactly that: MDA monitor + EGA WONDER 800 (the pure ega version)

Looking sharp!
I can also see that the EGA Wonder doesn't double-scan the low-res games on your MDA monitor... while in the OP's photos, they're clearly double-scanned and fill up the visible area.

That led me to answer my own question from my last post: it seems that the Philips Computer Monitor 80 (in MMaximus' photos) isn't MDA-only, and is probably not displaying MDA-compatible video in those photos.

From a bit of searching, this monitor does MDA/Hercules, but also Atom, MSX, Amiga/C64 and C128, all of which are far from MDA-spec... the C128 outputs basically the same RGBI video as CGA. So it's clearly designed to accept low-res color signals and convert them to monochrome internally, without any help from 'Wonder' cards.

Since a 400-line image should be out of range for MDA, I can only guess that's just what's happening in the OP's photos. The ATI boards must be sending the Philips a CGA/EGA signal, or a 25KHz one (this was used by some early 640x400 displays, like the Tandy 2000's or the Olivetti M24's; the EGA Wonder manual says it's supported).

The upshot is... I don't think we're really seeing how the ATI boards convert color to monochrome, but rather how the Philips monitor does it. 😉

Benedikt wrote on 2022-04-29, 19:30:

...
Does any kind of horizontal pattern show up on a closeup of the monochrome screen in areas that should technically show a solid color?

VileR wrote on 2022-04-29, 20:34:

...(do some of the shades look more flickery than others)?
On something with a p39 phosphor like an IBM 5151, it'd probably be much nicer.

I haven't really noticed a visible horizontal pattern and/or more flicker in certain shades than others, but then again maybe I wasn't paying enough attention. I'll look for this next time I have access to my systems and also run some tests on an IBM 5151 😀

keropi wrote on 2022-04-30, 16:20:

what a nice thread!
I remember I have these old pics from when I tried exactly that: MDA monitor + EGA WONDER 800 (the pure ega version)
...

Thanks for posting these keropi 😀

VileR wrote on 2022-04-30, 20:57:

Looking sharp! I can also see that the EGA Wonder doesn't double-scan the low-res games on your MDA monitor... while in the OP's […]
Show full quote

Looking sharp!
I can also see that the EGA Wonder doesn't double-scan the low-res games on your MDA monitor... while in the OP's photos, they're clearly double-scanned and fill up the visible area.

That led me to answer my own question from my last post: it seems that the Philips Computer Monitor 80 (in MMaximus' photos) isn't MDA-only, and is probably not displaying MDA-compatible video in those photos.

From a bit of searching, this monitor does MDA/Hercules, but also Atom, MSX, Amiga/C64 and C128, all of which are far from MDA-spec... the C128 outputs basically the same RGBI video as CGA. So it's clearly designed to accept low-res color signals and convert them to monochrome internally, without any help from 'Wonder' cards.

Since a 400-line image should be out of range for MDA, I can only guess that's just what's happening in the OP's photos. The ATI boards must be sending the Philips a CGA/EGA signal, or a 25KHz one (this was used by some early 640x400 displays, like the Tandy 2000's or the Olivetti M24's; the EGA Wonder manual says it's supported).

The upshot is... I don't think we're really seeing how the ATI boards convert color to monochrome, but rather how the Philips monitor does it. 😉

I have another theory... from the screenshots that keropi posted, it looks like he might have had his EGA Wonder 800 set to Hercules mode at the time. Remember the ATI Wonder series of cards is also supposed to be Hercules compatible (though in my experience it's a bit hit and miss with the 800+) so you can hook one up to a monochrome CRT and set it up to behave as a regular Hercules card. To me the screenshots from keropi look 100% Hercules: horizontally compressed, visible scanlines. OTOH my 800+ was set up to function as a standard EGA card for this test (thanks to the ATI utility software).

As for the Philips Monitor 80 - there have been many models sporting this designation, with several variations among them. I believe there were 3 colours of phosphor available: Green, Amber, or White. But more importantly, there were MDA versions and composite versions. I actually have two different models of Monitor 80 - a green composite one and an amber MDA one. They have been sold under different brands (Magnavox, Commodore, possibly others). AFAIK, one of the monitors that was bundled with the Commodore PC10-III was the Commodore 76BM13, which is a rebadged MDA version of the Monitor 80. Here is one I saw at the Athens computer museum a few years ago:

IIRC the Commodore PC10-III had an integrated ATI Graphics Solution / Small Wonder on the motherboard that would feed a proper MDA signal to this monitor, wether you would set the card to CGA or Hercules mode.

Here is the user manual for this monitor - spec sheet says 18 432Hz which I believe denotes MDA/Hercules.

Bonus Pic - my green composite Monitor 80 being fed an HDMI signal through a cheap HDMI to composite adapter 😄

MMaximus wrote on 2022-04-30, 22:13:

I haven't really noticed a visible horizontal pattern and/or more flicker in certain shades than others, but then again maybe I wasn't paying enough attention. I'll look for this next time I have access to my systems and also run some tests on an IBM 5151 😀

Nice - those would sure be interesting to see!

I have another theory... from the screenshots that keropi posted, it looks like he might have had his EGA Wonder 800 set to Hercules mode at the time. Remember the ATI Wonder series of cards is also supposed to be Hercules compatible (though in my experience it's a bit hit and miss with the 800+) so you can hook one up to a monochrome CRT and set it up to behave as a regular Hercules card. To me the screenshots from keropi look 100% Hercules: horizontally compressed, visible scanlines. OTOH my 800+ was set up to function as a standard EGA card for this test (thanks to the ATI utility software).

I dunno: keropi's SimCity shot shows different solid shades of amber in hi-res, which should only be possible in EGA. But I guess the rest of them might be in true Hercules mode. At least the Prince one does kinda look like that, maybe Zeliard/MM too.
Guess the only way to be sure with photos like the ones in this thread is to confirm the card's switch/software settings... ATI sure made things confusing by supporting so many combinations. 😉

As for the Philips Monitor 80 - there have been many models sporting this designation, with several variations among them. I believe there were 3 colours of phosphor available: Green, Amber, or White. But more importantly, there were MDA versions and composite versions. I actually have two different models of Monitor 80 - a green composite one and an amber MDA one. They have been sold under different brands (Magnavox, Commodore, possibly others). AFAIK, one of the monitors that was bundled with the Commodore PC10-III was the Commodore 76BM13, which is a rebadged MDA version of the Monitor 80. Here is one I saw at the Athens computer museum a few years ago:

Interesting, and now that you mention it, the Commodore 1084(s) also looks practically identical. I knew that one was a rebranded Philips monitor, but didn't make the connection until now. Write up Philips next to ATI in Club Confusion.

Yep, 18432Hz would be Hercules/MDA only as far as I know. Although it's still strange that it says either 50/60 Hz vertically - gotta wonder what the combination of 18 KHz / 60 Hz is good for.

If this monitor is indeed MDA-only, then I'll admit, I can't figure out how it supports double-scanned 200-line modes, as shown in your photos (i.e. 400 lines). Not that I underestimate ATI's engineering prowess, but the numbers still don't add up for me. 😀

I'm picking up this thread where I left off - in the ATI "ESETUP" EGA Wonder 800+ utility there is an option to "ADJUST TTL MONOCHROME GRAYSCALE". I set the slider to maximum brightness and it seems to make the display a bit brighter in games, although nowhere near as bright as the Small Wonder card.

The amber screenshot is with the Philips monitor, and the green is with an IBM 5151. It looks like the Philips monitor has more range between the different shades, whereas with the 5151 they look more similar overall.

I've also tried some games with the 800+ set to CGA mode but the Small Wonder still has the edge in display quality.

All in all, the ATI Small Wonder definitely is the better choice for monochrome gaming 😀

MMaximus wrote on 2022-04-27, 21:27:

POP EGAWndr.jpg
Prince of Persia in EGA mode with the EGA Wonder 800+. There is no dithering on the bricks but to me it's hard to tell that the game is displayed in EGA.

How did you get this to work? I have a PC XT with an ATI Wonder 800+, but Prince won't load regardless of how I set it up. It says "Graphics mode not available".

Worth noting, I've got an XT-CF card. I wonder if that's somehow conflicting, although I've tried moving its based address around to no avail.

franciozzy wrote on 2023-01-13, 21:31:

MMaximus wrote on 2022-04-27, 21:27:

POP EGAWndr.jpg
Prince of Persia in EGA mode with the EGA Wonder 800+. There is no dithering on the bricks but to me it's hard to tell that the game is displayed in EGA.

How did you get this to work? I have a PC XT with an ATI Wonder 800+, but Prince won't load regardless of how I set it up. It says "Graphics mode not available".

Worth noting, I've got an XT-CF card. I wonder if that's somehow conflicting, although I've tried moving its based address around to no avail.

Is your video card correctly set to EGA mode? In my experience Prince of Persia complains about "Graphics mode not available" when trying to launch the game in colour graphics (CGA, EGA or VGA) and only a monochrome adapter is present in the system.

My take is that your 800+ is set to hercules mode at the moment. If you set it up to EGA mode with the ATI utilities it should do the trick.

Bear in mind this card is better suited to a fast 286 though - EGA on an XT is slow at the best of times and it will be even slower with the 800+🤷

MMaximus wrote on 2023-01-14, 09:02:

Is your video card correctly set to EGA mode? In my experience Prince of Persia complains about "Graphics mode not available" when trying to launch the game in colour graphics (CGA, EGA or VGA) and only a monochrome adapter is present in the system.

My take is that your 800+ is set to hercules mode at the moment. If you set it up to EGA mode with the ATI utilities it should do the trick.

Bear in mind this card is better suited to a fast 286 though - EGA on an XT is slow at the best of times and it will be even slower with the 800+🤷

Yes I have it set to EGA Colour. Other games "work" (it's really slow as you said) both in CGA and EGA. I had success, for example, with:
- Alley Cat (CGA, works great)
- SimCity (very slow and crashed with a stack error at some point)
- Test Drive (playable)
- Stunts (loads, but too slow to play)

Any other thoughts? Did you run Prince 1.4 or some other version?

This is a 5160 with a 5151 monitor. I know... courage! 😀

I'm running Prince of Persia v1.3 - I haven't tried the EGA Wonder in an XT yet (all these games were tested on a 486 system 😀)

What a fantastic thread!

Are the ATi Wonder cards unique in supporting colour video modes on an MDA monitor? Or are there other cards out there that can do the same?

jamesfmackenzie wrote on 2025-01-13, 12:55:

What a fantastic thread!

Are the ATi Wonder cards unique in supporting colour video modes on an MDA monitor? Or are there other cards out there that can do the same?

Thank you! As far as I know they're the only cards to support this feature.

There are, however, some dual frequency MDA monitors that can accept a CGA signal and display it in monochrome, but I guess that's a story for another day 😁

Can this PWM signal drive an RGBI CRT in the same fashion it does a grayscale one? Intensity directly, Video to Green, would it yield a simulation of a greenscale monochrome on a colour monitor?

Asking because I'd like to find a replacement monitor for an Olivetti XT system that does this via Paradise chip, but the frequencies are out of spec for MDA and it's a 640x400 output.

The signal is 22kHz @ 47 Hz refresh. Can anybody point to RGBI monitor models that could sync to this?

The classic monitors from the NEC MultiSync series (except for the 2A) should be good. See original MultiSync, MultiSync II, MultiSync 3D and MultiSync 3DS. Newer monitors like the 3V and the 3FGe are VGA (and up) only.

Furthermore, the EIZO 8060S does this as well. I have one of those, and it worked well with that ancient (quite limited) C64 Emulator that outputs 640x400 on a Hercules card at quite similar timings. I could not find non-merchant liks for that monitor.

As for how to obtain one of those monitors, I have no suggestion except "good luck".

zb10948 wrote on 2025-02-07, 22:49:

Can this PWM signal drive an RGBI CRT in the same fashion it does a grayscale one? Intensity directly, Video to Green, would it yield a simulation of a greenscale monochrome on a colour monitor?

Asking because I'd like to find a replacement monitor for an Olivetti XT system that does this via Paradise chip, but the frequencies are out of spec for MDA and it's a 640x400 output.

The signal is 22kHz @ 47 Hz refresh. Can anybody point to RGBI monitor models that could sync to this?

Some fixed frequency screens including old vga ones have internal potl adjustments for v and h hold.

It is possible some may be able to be forced via manual adjustment to sync up.

I had an old rgbi NCR 640x400 screen and adapter that ran that odd refresh. I had a screen that could handle its refresh but because the sync polarity and termination was non standard I got a very strange scrambled but synced screen (upside down). There is also analog and TTL sync signals which add another variable

Understand that the sync polarity, termination and other under the hood characteristics may not resemble industry standard causing more frustration.

jamesfmackenzie wrote on 2025-01-13, 12:55:

What a fantastic thread!

Are the ATi Wonder cards unique in supporting colour video modes on an MDA monitor? Or are there other cards out there that can do the same?

Nope. AFAIK they're the latest. Paradise had a solution since 1984. Olivetti M19 has this on its integrated graphics. One of the Commodore PCs too.

Soon I will test 800+ on the MDA screen that's bundled with that Olivetti, it was not sold separately. Clearly produced and tested monitor for this case. Gonna try it on 486 to see how fast EGA games look like.

Will be first time to plug in 800+, it is jumperless, it should autodetect the screen and start immediately, and the EGA mode can be turned on via the utility. Anything else I need to watch out for?

zb10948 wrote on 2025-02-12, 17:12:

Soon I will test 800+ on the MDA screen that's bundled with that Olivetti, it was not sold separately. Clearly produced and tested monitor for this case. Gonna try it on 486 to see how fast EGA games look like.

Please keep in mind that support for 25kHz monitors, such as the 640x400 monitors that came with the Olivetti M24 and similar systems, is only available in EGA Wonder cards up to (and including) the EGA Wonder 800 (non-plus).

The EGA Wonder 800+ (800 Plus) uses a different chipset that does not support 25kHz monitors. I believe at that point ATI started using the same chipset as the one they used in their VGA Wonder cards (at least those that supported both TTL and analog monitors). Chips and Technology, if I recall correctly.

Also, on the cards that do support 25KHz (640x400) monitors, namely the EGA Wonder and EGA Wonder 800 (non-plus) cards, a jumper has to be set explicitly to enable support for such monitors.

And 25KHz monitors are not MDA monitors. They support higher frequencies and refresh rates.

Thanks for noting, but M24 screens DSM 2412 were pricey items not compatible with budget M19, which just drives regular MDA and RGBI screens, albeit at a modified timing.

DSM 1912 of M19 is a standard mono but with a wider sync ability. It will perfectly sync to 720x350@50Hz, 18kHz and 640x400@45Hz, 22kHz which M19 uses. Without touching internal controls.
Since 800+ claims compatibility with standard mono screens, I don't see a problem here?

zb10948 wrote on 2025-02-15, 02:03:

Thanks for noting, but M24 screens DSM 2412 were pricey items not compatible with budget M19, which just drives regular MDA and RGBI screens, albeit at a modified timing.

DSM 1912 of M19 is a standard mono but with a wider sync ability. It will perfectly sync to 720x350@50Hz, 18kHz and 640x400@45Hz, 22kHz which M19 uses. Without touching internal controls.
Since 800+ claims compatibility with standard mono screens, I don't see a problem here?

Ah, good to know. So I assume that the M19 drives a standard MDA/Hercules-compatible monochrome monitor in interlaced mode to get the 640x400 resolution?

And yes, The EGA Wonder 800+ and even the VGA Wonder cards with dual analog and TTL connectors should able to drive such screens.

I've been experimenting with an IBM 5151 monochrome monitor ("the" original MDA monitor) connected to an ATI VGA Wonder 16 card and that's been working fine for EGA emulation, including 640x350 resolution with 16 shades of grey, thanks to the Pulse-width modulation (PWM) trick used by these cards. One thing I've run into though, is that the screen is currently scrolling up vertically (not getting a stable lock) when I run games in 320x200 EGA 16-color (or "16 shades of grey") mode. Strangely enough, this does not occur in 320x200 4-color CGA mode. But from what I understood from a repair video on YouTube, the IBM 5151 monitor has internal adjustment wheels on the PCB that are not accessible from the outside, including one for Vertical Hold. I should probably try tweaking that one a bit. Hopefully I can get it to display a stable sceen at both 640x350 and 320x200 modes, without constantly having to adjust the wheel whenever I switch between the two modes.

By the way, the EGA Wonder 800 (non-plus) also implied that it supported the various palettes from the 64 colors in the EGA standard, even on CGA and 25kHz monitors that are only supposed to support 16 colors. Apparently, the same PWM trick is used to accomplish this on 16-color monitors. Does anybody have any experience with this yet?

I have an EGA Wonder 800 that I'd like to try with the monitor of my Dad's Olivetti M24 at some point, but I haven't gotten around to trying that yet.

digger wrote on 2025-02-17, 12:58:

Ah, good to know. So I assume that the M19 drives a standard MDA/Hercules-compatible monochrome monitor in interlaced mode to get the 640x400 resolution?

Interesting notion, what is exactly the "standard"?
If the standard screen is expected to sync up to 22kHz, then yes. If no, you can't hook M19 to it.

Is it interlaced, that I can't tell.

Unlike 800+, M19 doesn't support anything on anything. CGA gfx modes are universal. RGBI output has CGA text mode and Plantronics support. Mono output has 640x400 text mode and 640x400x2 mode support.

digger wrote on 2025-02-17, 12:58:

And yes, The EGA Wonder 800+ and even the VGA Wonder cards with dual analog and TTL connectors should able to drive such screens.

Yeah VGA Wonder replicates the same functionality, sadly no VGA stuff - tho the gist of it is impossible to implement targeting MDA-spec screens, so understandable.

digger wrote on 2025-02-17, 12:58:

I've been experimenting with an IBM 5151 monochrome monitor ("the" original MDA monitor) connected to an ATI VGA Wonder 16 card and that's been working fine for EGA emulation, including 640x350 resolution with 16 shades of grey, thanks to the Pulse-width modulation (PWM) trick used by these cards. One thing I've run into though, is that the screen is currently scrolling up vertically (not getting a stable lock) when I run games in 320x200 EGA 16-color (or "16 shades of grey") mode. Strangely enough, this does not occur in 320x200 4-color CGA mode. But from what I understood from a repair video on YouTube, the IBM 5151 monitor has internal adjustment wheels on the PCB that are not accessible from the outside, including one for Vertical Hold. I should probably try tweaking that one a bit. Hopefully I can get it to display a stable sceen at both 640x350 and 320x200 modes, without constantly having to adjust the wheel whenever I switch between the two modes.

Due to sync range of DSM 1912 and fact that it was tailor made for shades-on-MDA thing, I expect it to run flawlessly, although you can never know what can pop up...
Certainly, IBM 5151 may've been a solely listed supported monitor as it's the reference item, but I guess most of MDA screens around in usage in turn of the 90s weren't IBM 5151.

digger wrote on 2025-02-17, 12:58:

By the way, the EGA Wonder 800 (non-plus) also implied that it supported the various palettes from the 64 colors in the EGA standard, even on CGA and 25kHz monitors that are only supposed to support 16 colors. Apparently, the same PWM trick is used to accomplish this on 16-color monitors. Does anybody have any experience with this yet?

No but I intend to get to bottom of this, both 800+ and M19 case. The "PWM trick" isn't documented, people suppose it can be this or that. We shall see.

digger wrote on 2025-02-17, 12:58:

I have an EGA Wonder 800 that I'd like to try with the monitor of my Dad's Olivetti M24 at some point, but I haven't gotten around to trying that yet.

Don't forget to provide power to the M24 monitor since the video connector has two +15VDC lines...

zb10948 wrote on 2025-02-19, 16:16:

Don't forget to provide power to the M24 monitor since the video connector has two +15VDC lines...

I believe only monochrome M24 monitors are powered through those lines. Color monitors have a separate 230V cable that plugs into the IEC C13/C14 power output port of the the PSU of the M24.