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Questioning myself about the importance of true IBM CGA

C

CarlosTex

Experienced Member
Joined
Mar 26, 2013
Messages
272
Nowadays it's really hard to find a RGBi monitor to display proper IBM CGA. Having a true IBM CGA card is really important for compatibility. I was however quite surprised by the ability of OAK cards, namely the OTI-037C, to emulate RGB CGA. But if someone chooses the easy path of a VGA card that has acceptable RGB CGA simulation he/she must be ready to accept that composite color mode can't be used when it is in fact the better looking option.

So the question actually is, how many and which games fall into the following categories:

- Looks better in CGA composite color than RGB CGA;
- Does not support EGA;

Can someone mention the games that look better on CGA composite but do not support EGA, or don't have a later version that does? Because even Starflight, a game that i can't imagine to live my life without playing it, supports EGA in a later version. Same with AGI games. I really can't think of a really good game that looks better on CGA composite than RGB but doesn't support EGA. Gosh, maybe M.U.L.E.?


So i really have a chance to get a Sony PVM monitor locally. It doesn't have a digital RGB input, but does have a SCART connector with which i can use the C128 RGB to VGA converter. It accepts a 15.7KHz signal so that's great. But i'm kinda questioning if its really worth it.
 
CarlosTex said:
So the question actually is, how many and which games fall into the following categories:

- Looks better in CGA composite color than RGB CGA;
- Does not support EGA;
Click to expand...

These are actually the same category. Games that look better in composite than RGB, are also early enough that they don't have an EGA version, or a later EGA patch.

Can someone mention the games that look better on CGA composite but do not support EGA, or don't have a later version that does?
Click to expand...

Here is a list of games I have personally played that look better in composite CGA than RGB CGA, and no EGA version exists:

Archon
Below The Root
Bruce Lee (although Tandy/PCjr version exists)
Burgertime (looks GREAT on composite CGA, almost identical to arcade)
Frogger II: Threedeep
All of the Infocomics
Microsoft Flight Simulator 1 and 2 (later versions support EGA and higher)
Oils Well (original version, although I think a Tandy version might exist?)
Pitstop II
Seven Cities of Gold (although supports Tandy graphics)
Spy Hunter
Super Zaxxon
Tapper
early Ultima games

You will notice most of these are booters. I haven't played EVERY game that ever supported composite CGA, but I have played many if not most of them, so I would consider the above list about 60-70% complete.

So i really have a chance to get a Sony PVM monitor locally. It doesn't have a digital RGB input, but does have a SCART connector with which i can use the C128 RGB to VGA converter. It accepts a 15.7KHz signal so that's great. But i'm kinda questioning if its really worth it.
Click to expand...

It's worth it if the cost isn't too high, because the PVM can be used for other applications (game consoles, you can use it with a Hercules card in your system to have a dual-monitor system, etc.)

Another reason to get a true CGA card is for the games that have timing effects or tweaked video modes that, no matter how good the Oak is, probably won't run correctly unless they're on a real CGA on a real 4.77MHz 8088. That list:

Games that use a tweaked or custom video mode: Super Zaxxon, Astro Dodge
Games that use palette switching on a raster line: Jungle Hunt, Frogger
Games that use low-res text-based 160x100 mode: Moon Bugs, Styx, Round 42, ICON, Seven Spirits of Ra
 
CarlosTex said:
Having a true IBM CGA card is really important for compatibility.
Click to expand...

I'm not sure if I agree with that.
I grew up with a Commodore PC10-III, which has a Paradise PVC4 clone.
I've never had any issues with compatibility with CGA games (demos didn't exist), in RGBI mode.
I've also tried the composite output, and although the colours aren't exactly the same as on a real IBM card, it's close enough.
Eg, see here my capture of the Keen 4 composite CGA remake:

I think the only software that really 'needs' a true IBM CGA card is 8088 MPH. But for the 'regular' 16 colour composite mode, the Paradise is close enough, and there are probably various other clones that also do a good job (the Compaq CGA clone is also really good. In fact, it even does 8088 MPH very convincingly).
 
The best things about IBM CGA is that games are guaranteed to work with it and artifact colors will be accurate. Not all CGA clones can boast 100% compatibility and show proper artifact colors. The tint control on your monitor/TV can only do so much.
 
Scali said:
I think the only software that really 'needs' a true IBM CGA card is 8088 MPH.
Click to expand...
Pretty much all the 160x100 16 colour non-composite games other than ONE (tunneler) prior to mine (Paku Paku), will go tits-up face-down on anything other than a legitimate CGA... so moonbugs, round42, styx, the Exterminator, etc, etc? Won't work on EGA/Newer. AT ALL. The port to set the mode doesn't even exist.

... and Tunneler's EGA implementation is wonky as the aspect ratio is wrong (it uses only 300 lines of the 350 available) and both their EGA and VGA version will have every even column one "hardware pixel" wider than the odd ones; both things I set out to fix with my implementation by forcing EGA to 640x200 and VGA to 640x400 instead of the 720x350 and 720x480 that's the default text modes on which the 160x100 semigraphics is based.

I often compare it to how TRS-80 Model 4 semigraphics looked like ass since the 3 graphic pixels divided amongst 10 hardware ones vertically meant every third pixel was taller!

So you want to play moonbugs, you need a real CGA, or get used to DOSBox. (I always found moonbugs very professional and well written -- never understood why the dung-heap that was Round 42 was the poster child)

-- as to the topic of this thread, I really haven't had too much trouble getting decent CGA displays still. Admittedly you often have to settle but Tandy CM-5's are cheap and sufficient to MOST tasks (other than 80x25 text) and common enough. I love the CM-11 I have, and honestly when it comes to displaying CGA modes, I'd stack it up against my 5154... which you'd think would be better since the latter is a EGA display.

Though right now my 5154 is hooked up to a Hercules inColor card.
 
Last edited:
deathshadow said:
Pretty much all the 160x100 16 colour non-composite games other than ONE (tunneler) prior to mine (Paku Paku), will go tits-up face-down on anything other than a legitimate CGA... so moonbugs, round42, styx, the Exterminator, etc, etc? Won't work on EGA/Newer. AT ALL. The port to set the mode doesn't even exist.
Click to expand...

Yes, CGA games generally don't work on EGA/VGA, since EGA/VGA aren't fully backward-compatible. Even the VGA cards that have a 'CGA mode' generally have limited compatiblity (at the very least, 200 line mode on a VGA monitor is 70 Hz, even when using it in 'CGA' mode, so things like hsync/vsync polling will be off, timing-wise).

But I meant that you don't need an IBM CGA per se. Most clone CGA cards use a real 6845 chip (either physical or integrated), and as such are compatible with 160x100 and various other tweaked modes/tricks.
 
Great Hierophant said:
The best things about IBM CGA is that games are guaranteed to work with it and artifact colors will be accurate. Not all CGA clones can boast 100% compatibility and show proper artifact colors. The tint control on your monitor/TV can only do so much.
Click to expand...

Of course... Which IBM CGA?

(There's two versions, the difference between them being how RGB colors are translated to composite.)
 
Most games authored for CGA composite color graphics were done so with the older card's colors in mind. (If that statement needs clarification, I'm sure GH will correct me :)
 
Flightmare offers both RGB and composite mode, where composite mode uses artifacting to produce additional colors.

screenshot_e2dbf-monitor-type-selection.png


And Novatron also uses composite artifacted colors:

screenshot_18f-novatron-game-start-don-t-crash-into-walls.png


These are just a few among many pre-EGA games.
 
I am unobservant!

My favorite "pop" from going from 4-color to composite CGA is still Burgertime. It looks incredibly close to the original arcade game when set to composite mode. (Gameplay is nearly identical too!)
 
Thank you all for the input.

Indeed Burgertime looks amazing. I couldn't get Burgertime booter version to work on my XT yet, i get some assembly code errors. But there's always the DOS conversion, and it's a well worth game indeed.

I should have mentioned that i have IBM CGA "New" version. This seems the easiest to find version. I know the cards can be modded, but i prefer to find an "old" card eventually.
 
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