ATI Small Wonder Graphics Solution v1

[Anonymous Coward]

What about emulating 320x200 EGA?

 

[Fallo]

I'm not only talking about color bleed, Seriously, with one combination of colors, some of the left parts of the picture went out of the screen and the remaining was compleetely mis-colored and bleeding as much as I never has seen before! However, there was no zig-zaging when that screen was showed.

The color bleed on the CGA composite output is dependent on the position of the pixels. If the widescreen mode was distorting them, it's natural that you would get out-of-whack colors.

What about emulating 320x200 EGA?

That wouldn't be possible. The Plantronics modes are mostly the same as the Tandy ones from a programming standpoint, but EGA graphics are completely different.

 

[Anonymous Coward]

Yeah. I guess if it were feasible then some Tandy or PCjr user would have done it by now. There still must be some way to get this damn Graphics Solution to emulate PCjr/Tandy video modes. It's kind of a waste having hardware that can handle 320x200 and 640x200 in 16 colours when nothing can take advantage of it.

 

[FishFinger]

I'm not only talking about color bleed, Seriously, with one combination of colors, some of the left parts of the picture went out of the screen and the remaining was compleetely mis-colored and bleeding as much as I never has seen before! However, there was no zig-zaging when that screen was showed.

That sounds very much like the problem I had with my LCD TV. The picture was all over the place and the colours would vary considerably depending on their position on the screen.

I switched the TV out of widescreen mode and it looked a lot better. I keep meaning to make up a CGA->Scart cable to see if that makes things better too.

 

[per]

That sounds very much like the problem I had with my LCD TV. The picture was all over the place and the colours would vary considerably depending on their position on the screen.

I switched the TV out of widescreen mode and it looked a lot better. I keep meaning to make up a CGA->Scart cable to see if that makes things better too.

I'm not sure about Scart. Remember that Scard is an Europeian standard and intended to be used with PAL signals. The CGA provides NTSC signalling...

Most LCD TV's today can however understand NTSC (even in Europe), at least for the composite input. I am not sure about if it will accept it through the Scart input.

Anyways, if you haven't decided on the card yet, I suggest you take it. At least if you got an 8088-based PC/XT.

 

[FishFinger]

PAL or NTSC doesn't matter. Scart is really just a cabling standard. If the TV can support NTSC (mine does) then it should be fine.

I've decided to buy the card, the extra modes are a nice upgrade.

 

[Fallo]

That sounds very much like the problem I had with my LCD TV. The picture was all over the place and the colours would vary considerably depending on their position on the screen

That's why you ought to keep a CRT for all your vintage equipment. Anything less than an Xbox 360 or a PS3 won't look very good on LCDs.

 

[JT64]

I don't see why this would occure, i mean most multimedia devices output composite video,(even old VHS recorders use composite on one SCART channel).

Is this somehow a different composite signal, why should an old tube TV work better, i just do not get it.

JT

Edit i was thinking TV when you said CRT, but on the other side not many CRT use CGA,EGA

 

[Fallo]

Is this somehow a different composite signal, why should an old tube TV work better, i just do not get it.

I have read many posts on different forums about people who used their vintage computers/consoles on LCD or plasma sets and found the picture quality to be poor, even with widescreen mode turned off. The problem isn't the signal; it's the fact that most of these TVs are high-definition sets, which generally do not handle standard-definition 480i or 240p signals properly. HD sets will often upscale them to higher resolutions, resulting in a distorted picture with bad colors. Basically, anything up to the PSX and N64 was designed to work with an analog CRT, and thus on LCD or plasma televisions will not look quite right.

 

[vwestlife]

Sw 1/1 ON = Monochrome monitor
Sw 1/1 OFF = RGBI or Composite monitor

Sw 1/2 ON = CGA/Plantonics Color+ graphics mode
Sw 1/2 OFF = MDA/Hercules graphics mode

Sw 1/3 ON = Composite in Color
Sw 1/3 OFF = Composite in Monochrome (IBM PC portable)

Sw 1/4 = Nothing (used on the very few 'g' versions of the card with a joystic port instead of the composite out)

I think you got SW1/1 and SW1/2 reversed. I have an ATI Small Wonder in my Packard Bell Turbo-XT. It claims to be "Version 2" but the board layout looks almost identical to Version 1 (except the onboard RCA jack for composite video output is not included), and totally different from the "Version 2" layout shown on stason.org.

Anyway, I wanted to try out the MDA emulation on my CGA monitor so I set the computer's motherboard switches for monochrome, but in order to get it to work, I had to set SW1/1 to ON, while leaving SW1/2 ON (as normal for CGA on a CGA monitor). So it appears that SW1/1 sets the display mode (CGA or MDA) while SW1/2 sets the monitor type (monochrome TTL or color RGB). Stason's switch settings for Version 1 concur with this.

The interlaced MDA emulation on an RGBI CGA monitor works amazingly well, if you can stand the flickering. It even emulates green phosphor! There are no missing pixels or scan lines out of the 720x350 display; it just looks a bit fuzzy due to the higher dot pitch of a typical CGA monitor (although no worse than many of the cheaper color VGA monitors that were sold!).

However, at least on my card, the composite output while in interlaced MDA emulation mode is very poor, regardless if I have SW1/3 set on or off. On a color TV set it refuses to display at all, and on my Taxan monochrome composite monitor I had to tweak the V-Hold and H-Hold quite a bit to get a stable image, and even then it produces very dim image with ragged edges.

Also, this card produces an extermely ugly text font while in 320x200 or 640x200 CGA graphics mode on a CGA or composite monitor. Is there any way to switch it back to the standard IBM CGA font, perhaps by using one of the undocumented jumpers? The text mode font is the regular IBM CGA "thick" font; it's just the graphics mode font that looks like it came off of a Star Wars title screen.

 

[JohnElliott]

Also, this card produces an extermely ugly text font while in 320x200 or 640x200 CGA graphics mode on a CGA or composite monitor. Is there any way to switch it back to the standard IBM CGA font, perhaps by using one of the undocumented jumpers? The text mode font is the regular IBM CGA "thick" font; it's just the graphics mode font that looks like it came off of a Star Wars title screen.

The font in CGA graphics modes comes from your computer's BIOS, not the graphics card. I suppose in theory you could load a TSR to change it -- has anyone seen such a beast?

 

[per]

The font in CGA graphics modes comes from your computer's BIOS, not the graphics card. I suppose in theory you could load a TSR to change it -- has anyone seen such a beast?

GRAPHICS.COM (included with most versions of DOS) is such a program, but it contains only the later half of the character set. The first half is stored within the BIOS, and can in fact not be changed unless you totally replace the entire INT 10h BIOS graphics routine with a TSR. The graphics routine in the TSR must also include the original IBM font for this to work.

 

[per]

I think you got SW1/1 and SW1/2 reversed. I have an ATI Small Wonder in my Packard Bell Turbo-XT. It claims to be "Version 2" but the board layout looks almost identical to Version 1 (except the onboard RCA jack for composite video output is not included), and totally different from the "Version 2" layout shown on stason.org.

Thanks for notifying. I must have written it before I turned the scans in the rigth direction.

By the way:
The manual doesn't really list MDA emulation on composite in the list of posibilities, so I actually don't think that is supposed to work...

 

[JohnElliott]

GRAPHICS.COM (included with most versions of DOS) is such a program, but it contains only the later half of the character set. The first half is stored within the BIOS, and can in fact not be changed unless you totally replace the entire INT 10h BIOS graphics routine with a TSR. The graphics routine in the TSR must also include the original IBM font for this to work.

That was rather my point; I've only seen programs (like GRAPHICS.COM) doing the second half of the character set. I think a possible approach when writing the TSR would be to set the INT 1F vector depending on whether the character was in the first or second half of the set, then OR the character with 80h and hand off to the original BIOS.

 

[per]

That was rather my point; I've only seen programs (like GRAPHICS.COM) doing the second half of the character set. I think a possible approach when writing the TSR would be to set the INT 1F vector depending on whether the character was in the first or second half of the set, then OR the character with 80h and hand off to the original BIOS.

That would in fact be very easy to program! Just wait a moment...

 

[vwestlife]

The font in CGA graphics modes comes from your computer's BIOS, not the graphics card. I suppose in theory you could load a TSR to change it -- has anyone seen such a beast?

Here is how the normal CGA modes show up on my Packard Bell PB 500 with the ATI card and a Tandy CM-11 monitor:

 

[vwestlife]

And here are the 16-color ATI/Plantronics graphics modes, which somehow use the normal CGA font instead, as well as the MDA/Hercules emulation... the interlacing doesn't pick up correctly on my camera, but it looks fine on the monitor (albeit flickery!), with no missing scan lines:

 

[per]

Here is a small utility that forces through the IBM character set in graphics mode. It's recomended to change to graphics-mode before running the program. It's written in quick-and-dirty style, so you may expect to reboot to undo the effect of the program.

 

[JohnElliott]

And here's my elaborate version, supporting loading fonts from files and unloading the TSR on request. It comes preloaded with the font from FreeGEM rather than the IBM ROM BIOS, because that was what I happened to have to hand (and I think it's a nicer font )

 

[per]

And here's my elaborate version, supporting loading fonts from files and unloading the TSR on request. It comes preloaded with the font from FreeGEM rather than the IBM ROM BIOS, because that was what I happened to have to hand (and I think it's a nicer font )

NOW I see why I didn't get that only-active-when-graphics-mode-is-active thing to work. Forgot to use [cs:variablename].