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.
digger wrote on 2025-02-21, 20:35: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.
Yeah. Didn't pick up you have colour one.
I've tested 800+ on M19's screen and it's working well. Phosphor persistence makes it a bit murky in detailed scrollers like Secret Agent, otherwise it's perfectly fine.
One detail with it, when I connected it my monitor started hissing. So I quickly disconnected that, and went to test the card using an upscaler. I saw that card needs 10-15 seconds to come alive through monitor detection. I have another M19 monitor which is burnt out, so I guessed it's better to try to pull that one through that initial phase. To my surprise it didn't hiss at all, and produced an image those ~15 seconds after.
I reconnected the 'normal' M19 monitor, it hissed, showed an image, then as I was about to pull out a spectrometer to see what freq is hissing, it went silent...and there is no more hiss anytime, not even on power on.
Afterwards I did an hours worth of testing and messing around and everything seems normal.
Wonder what that's all about. I've already used this screen on a MDA clocked signal coming out of Gemini microEGA, nothing out of the ordinary whatsover...
