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First post, by jwt27

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I have these two CGA/MDA/Herc cards and I'm looking to try them out once I get my DOS machine running again. I tried both a while ago but they didn't work correctly.

First, the ATI Small Wonder v2. Problem here is, the BIOS chip is missing. Without it, its Hercules mode works correctly with a second VGA card installed. MDA mode won't show any text, however, and on its own it won't boot at all. I'm hoping someone who has this card could make an image of the BIOS for me.

Next, the TECMAR Graphics Master. It looks very interesting, being a full-length six-layer card, jampacked with chips, and I found a magazine ad on google which claims it supports 720x700 interlaced MDA mode. Unfortunately though, I couldn't get it to do anything at all. This card has a gazillion jumper settings which are probably set all wrong and the only documentation I can find (here) is, uh, confusing, to say the least. Does anyone have any more information about it?

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Reply 2 of 35, by Anonymous Coward

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I once had a Tecmar Captain 286 RAM expansion card for 286s. It also had a gazillion jumpers and the docs were either incomplete or missing. I was never able to figure it out and after keeping it for 10 or more years I threw it out.

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V'Ger XT|Upgraded AT|Ultimate 386|Super VL/EISA 486|SMP VL/EISA Pentium

Reply 3 of 35, by jwt27

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Robin4 wrote:

Only EGA and VGA Wonder there... I don't think that would work. The Small Wonder only supports CGA, MDA, Hercules, and a special interlaced-Hercules-over-composite-CGA mode.

Anonymous Coward wrote:

I once had a Tecmar Captain 286 RAM expansion card for 286s. It also had a gazillion jumpers and the docs were either incomplete or missing. I was never able to figure it out and after keeping it for 10 or more years I threw it out.

Hm. Too bad 🙁
I found some more docs on an FTP site, looks like there's some information on your Captains board too. For the Graphics Master, there's not much more information than on the other site, but at least it's a bit more detailed.

ftp://oldskool.org/pub/tvdog/tandy1000/faxback/00_index.txt
ftp://oldskool.org/pub/tvdog/tandy1000/faxback/05546.pdf
ftp://oldskool.org/pub/tvdog/tandy1000/faxback/02075.txt
ftp://oldskool.org/pub/tvdog/tandy1000/faxback/02076.txt
ftp://oldskool.org/pub/tvdog/tandy1000/faxback/02077.txt
ftp://oldskool.org/pub/tvdog/tandy1000/faxback/02078.txt
ftp://oldskool.org/pub/tvdog/tandy1000/faxback/02079.pdf

Still, what's the difference between a "reset" and "secondary" monitor? I assume the "reset" monitor is the one enabled on boot/reset. But then how do you switch to the secondary screen?
Also when I found this board, the jumper settings were completely different from any configuration described in the docs. Maybe I should've wrote them down...

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Reply 4 of 35, by jwt27

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Bump. Got this Tecmar card to work somehow. Don't ask how. I tried swapping some jumpers again and suddenly it just worked.
Anyway, this card supposedly supports some odd resolutions, for example 720x704i in MDA mode and possibly also CGA emulation, but I think this required some special drivers. Does anyone know where to find these?

And I have another card, Paradise Autoswitch EGA 350, which I also thought to be dead but suddenly worked again after re-seating the big PLCC chip (and I've done that several times before). It appears to support 50-line mode in MDA which is kinda neat, but no hardware CGA/EGA emulation as far as I can tell. Again I believe drivers are necessary here, does anyone happen to have them?

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Reply 5 of 35, by Scali

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jwt27 wrote:

First, the ATI Small Wonder v2. Problem here is, the BIOS chip is missing. Without it, its Hercules mode works correctly with a second VGA card installed. MDA mode won't show any text, however, and on its own it won't boot at all.

What exactly *is* MDA mode then?
I have an ATi Small Wonder v1 myself, and afaik it only does CGA and Hercules modes. See also these switch settings: http://www.vintage-computer.com/vcforum/showt … 3732#post113732
There is no separate 'MDA' setting, just MDA/Hercules.
Seeing as Hercules is little more than MDA with optional graphics features (with no BIOS support, so you have to manually modify the chip's registers to enable it), I don't see why there would be an MDA mode in the first place.
Hercules textmode is 100% the same.

http://scalibq.wordpress.com/just-keeping-it- … ro-programming/

Reply 6 of 35, by jwt27

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Yes, I realize Hercules is the same as MDA with an additional graphics mode. By "Hercules mode" I basically mean monochrome graphics, and by "MDA mode" I mean monochrome text. Sorry for the confusion 😀

The problem with the Small Wonder card is, it won't show any text since there is no character rom, and it won't boot on its own (without a second graphics card installed) since the video BIOS is missing.

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Reply 7 of 35, by Scali

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jwt27 wrote:

Yes, I realize Hercules is the same as MDA with an additional graphics mode. By "Hercules mode" I basically mean monochrome graphics, and by "MDA mode" I mean monochrome text. Sorry for the confusion 😀

That's still confusing though, since the card also supports monochrome CGA, and MDA/Hercules-modes-on-CGA-monitor as well as CGA-modes-on-MDA/Hercules-monitor 😀

jwt27 wrote:

The problem with the Small Wonder card is, it won't show any text since there is no character rom, and it won't boot on its own (without a second graphics card installed) since the video BIOS is missing.

Yea, makes sense. I could make a dump of my Small Wonder V1 ROM with debug if you like (need to know exactly how to do that). As far as I can tell, the v2 version is nearly the same card, just a minor revision of the PCB. Should be good enough to get a character set. I don't think there's anything else in that ROM, since Plantronics/Hercules don't have any BIOS API at all, and CGA/MDA BIOS is contained in the PC/XT ROM itself, not on the card.
So I bet that just like real IBM MDA/CGA, the ROM just contains the fonts. You might even be able to use an IBM MDA ROM to get the font working.
There is also a dump in this thread: http://www.vintage-computer.com/vcforum/showt … ics-ROM-missing
And after some messing about, he got it working: http://www.vintage-computer.com/vcforum/showt … 8498#post358498

http://scalibq.wordpress.com/just-keeping-it- … ro-programming/

Reply 8 of 35, by jwt27

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Scali wrote:

That's still confusing though, since the card also supports monochrome CGA, and MDA/Hercules-modes-on-CGA-monitor as well as CGA-modes-on-MDA/Hercules-monitor 😀

Oh well.. At least you know what I mean right? 😀

Scali wrote:

There is also a dump in this thread: http://www.vintage-computer.com/vcforum/showt … ics-ROM-missing
And after some messing about, he got it working: http://www.vintage-computer.com/vcforum/showt … 8498#post358498

Thanks! I haven't seen these threads yet.. Funny coincidence, he had exactly the same problem, two months after me. 😀
Looks like I need an account to download the ROM there. Hmm. Guess it's about time I registered there, anyway.

Scali wrote:

You might even be able to use an IBM MDA ROM to get the font working.

Don't think that would work right away, since MDA uses a 2364 rom. The pinout is quite different from 2764. I do have an adapter socket so I could give it a try.

Now if only I could find this Ati card again...

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  • Paradise Autoswitch EGA 350 (EGA1A)

Reply 9 of 35, by Scali

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jwt27 wrote:

Don't think that would work right away, since MDA uses a 2364 rom. The pinout is quite different from 2764. I do have an adapter socket so I could give it a try.

I was thinking of using an MDA ROM dump, and flashing the contents into a 2364 ROM.
But since the ATi ROM dump is already uploaded to VCF, you might as well get the real thing 😀

http://scalibq.wordpress.com/just-keeping-it- … ro-programming/

Reply 10 of 35, by jwt27

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Okay I found the Small Wonder card again, and a 27C256 eprom from an old modem. Erased and reflashed with the ROM from VCF, four times just to be sure, and... it works! Yeah! Thanks Scali 😀

Now, first impressions, this card does some pretty amazing things. It provides full hardware CGA emulation, and somehow even manages to display SIXTEEN distinct shades of green on a 5151 monitor. Uh, wow! I had no idea this was even possible. I thought the 5151 could technically only display three shades (of which only two were ever used). How does this even work?

Composite works too, although my PAL screen won't display any colours. Oh well, can't have it all, I suppose.

WANTED - Manuals/drivers for:

  • Tecmar Graphics Master
  • Paradise Autoswitch EGA 350 (EGA1A)

Reply 11 of 35, by Scali

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jwt27 wrote:

Now, first impressions, this card does some pretty amazing things. It provides full hardware CGA emulation, and somehow even manages to display SIXTEEN distinct shades of green on a 5151 monitor.

It can also do it the other way around.
So you can get Hercules on a CGA monitor. It does that by creating a 640x400 interlaced mode with overscan to get a virtual 720x350 resolution. It even does it with green, so you get that 5151-vibe 😀

jwt27 wrote:

Composite works too, although my PAL screen won't display any colours. Oh well, can't have it all, I suppose.

Even if you get an NTSC composite display, it's of limited use. The direct colours are okay, but the artifact colours don't match up with CGA, so games tend to look completely wrong/bad.

http://scalibq.wordpress.com/just-keeping-it- … ro-programming/

Reply 12 of 35, by jwt27

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Scali wrote:

It can also do it the other way around.
So you can get Hercules on a CGA monitor. It does that by creating a 640x400 interlaced mode with overscan to get a virtual 720x350 resolution. It even does it with green, so you get that 5151-vibe 😀

I tried this on the composite screen (1084S-D2), but it won't sync to this resolution. 60Hz is no problem however.

Scali wrote:

Even if you get an NTSC composite display, it's of limited use. The direct colours are okay, but the artifact colours don't match up with CGA, so games tend to look completely wrong/bad.

Ah, that's too bad... I was actually thinking of picking up an NTSC tv tonight just for this. I got some other CGA cards I could try it with though, like the Tecmar and Paradise.

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Reply 13 of 35, by Scali

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jwt27 wrote:

I tried this on the composite screen (1084S-D2), but it won't sync to this resolution. 60Hz is no problem however.

I don't think the composite output is capable of interlace. I only tried it via RGBI, and it worked fine.

jwt27 wrote:

Ah, that's too bad... I was actually thinking of picking up an NTSC tv tonight just for this. I got some other CGA cards I could try it with though, like the Tecmar and Paradise.

I don't know about Tecmar, but Paradise has the same issue of wrong artifact colours.

http://scalibq.wordpress.com/just-keeping-it- … ro-programming/

Reply 14 of 35, by jwt27

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Scali wrote:
jwt27 wrote:

I tried this on the composite screen (1084S-D2), but it won't sync to this resolution. 60Hz is no problem however.

I don't think the composite output is capable of interlace. I only tried it via RGBI, and it worked fine.

It works in CGA composite mode, that's interlaced right? Only Hercules over composite won't sync.

Some pics btw:

tmMcBF2.jpg

8N1I39W.jpg

3ygvzKk.jpg

I'm really curious, how does this work? The 5151 is digital and only has a 2 bit video signal (video+intensity), so that should be three shades and black. Or, is the video pin analog after all?

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Reply 15 of 35, by Scali

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jwt27 wrote:

It works in CGA composite mode, that's interlaced right? Only Hercules over composite won't sync.

I was talking about using the Hercules-compatible mode on a CGA monitor (so with the card output dip-switches configured for CGA). It does this by using interlacing (on RGBI at least, not sure about composite).

Composite is not interlaced. True NTSC is interlaced, because you have even and odd fields, which are offset by half a scanline. CGA composite is not interlaced, and all fields are the same, so just 60 Hz non-interlaced.

MDA/Hercules output at 50 Hz, not 60 Hz, which is why an MDA/Hercules monitor can't be used on a CGA TTL output, or vice versa. What makes the Small Wonder special is that it can simulate Hercules on a CGA monitor, and it can simulate CGA on a Hercules monitor (Paradise can also do this).

Real MDA/Hercules have no composite output, only CGA did. Clones such as the Small Wonder probably haven't bothered to make the composite output support MDA/Hercules at all. Being 50 Hz, it would be impossible to make the signal NTSC-compatible anyway.

I'm really curious, how does this work? The 5151 is digital and only has a 2 bit video signal (video+intensity), so that should be three shades and black. Or, is the video pin analog after all?

From these pictures it's not clear whether you actually see more than 4 different shades of green. If you are, then I have no idea how that would work.

http://scalibq.wordpress.com/just-keeping-it- … ro-programming/

Reply 16 of 35, by jwt27

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Scali wrote:

From these pictures it's not clear whether you actually see more than 4 different shades of green. If you are, then I have no idea how that would work.

Count them 😀
It may be hard to tell on the pictures but the second pic is really 16 shades. Some do appear identical, but if I turn the contrast all the way down, the top row disappears completely, and both rows are equal with max contrast. I think this means that the bottom row has the intensity bit set, while the columns are displayed by varying the video signal.

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Reply 17 of 35, by jwt27

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Got the scope out. This is the monochrome video signal (one scanline in the colour bar pattern):

owUbanv.jpg

Which looks suspiciously similar to a composite video signal...

ntscdb1fig4.gif

What's going on here? Am I looking at some super fine pwm/dithering pattern?

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Reply 18 of 35, by Scali

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Well, I know I read somewhere that some cards use the mono pin on the 9-pin TTL output for a composite signal. Perhaps that is what you're seeing here?
It indeed looks like there's some kind of high-frequency modulation going on there, because you get these 'bars'.

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Reply 19 of 35, by jwt27

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Scali wrote:

Well, I know I read somewhere that some cards use the mono pin on the 9-pin TTL output for a composite signal. Perhaps that is what you're seeing here?
It indeed looks like there's some kind of high-frequency modulation going on there, because you get these 'bars'.

I think it's PWM modulation, which would explain why the "bars" appear to have a different amplitude; my scope just doesn't have enough bandwidth to resolve this. I can zoom in a bit further but it looks more or less like a sine wave.

Scali wrote:

I was talking about using the Hercules-compatible mode on a CGA monitor (so with the card output dip-switches configured for CGA). It does this by using interlacing (on RGBI at least, not sure about composite).

It doesn't seem able to do interlacing on Hercules (or CGA-on-Hercules) though, unlike the Tecmar card. I don't have a real CGA monitor to test the other way around.

Scali wrote:

simulate CGA on a Hercules monitor (Paradise can also do this).

The Autoswitch EGA too? I can't seem to get this to work, and I read somewhere that this requires an emulation driver. I don't believe it could do the same colour emulation as this ATi.
Now I'm curious about the VGA (and EGA) Wonder cards. Can these do full VGA emulation with 256 shades of green on a 5151...?

Also, just found out, I have a Hyundai 8088 mainboard with integrated ATI Small Wonder on-board! 😳
which also means... I had the original character ROM already...

WANTED - Manuals/drivers for:

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