Not cheap, but this is probably the best option right now:

https://www.youtube.com/watch?v=9SII7ujB3FY

You can also build your own converter, check out this thread:

http://www.vcfed.org/forum/showthread.php?505 … 6670#post396670

I have a XT clone with a SVGA trident card, and I also have run into compatibility with older CGA games. I am willing to live with it at the moment, but a EGA/CGA card would definitely work better.

VGA is not register-compatible with CGA. This is by design. Some SVGA cards have a special CGA-compatibility mode, that make it somewhat register-compatible, but none are 100%.
Aside from that, 320x200 mode is 60 Hz on CGA, but 70 Hz on a VGA monitor. So timing will be different.
Also, in general, VGA cards are much faster than real CGA cards.

Not to mention that VGA does not offer composite output, so you're limited to RGBI games. A regular CGA to VGA converter would not do that either, but well, firstly, most CGA cards have a composite output you can use directly on a TV. And secondly, there are some CGA to VGA converters that actually do have composite emulation, such as this one: MDA/CGA/EGA to VGA Converter Released!

Scali wrote:

VGA is not register-compatible with CGA. This is by design. Some SVGA cards have a special CGA-compatibility mode, that make it […]
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VGA is not register-compatible with CGA. This is by design. Some SVGA cards have a special CGA-compatibility mode, that make it somewhat register-compatible, but none are 100%.
Aside from that, 320x200 mode is 60 Hz on CGA, but 70 Hz on a VGA monitor. So timing will be different.
Also, in general, VGA cards are much faster than real CGA cards.

Not to mention that VGA does not offer composite output, so you're limited to RGBI games. A regular CGA to VGA converter would not do that either, but well, firstly, most CGA cards have a composite output you can use directly on a TV. And secondly, there are some CGA to VGA converters that actually do have composite emulation, such as this one: MDA/CGA/EGA to VGA Converter Released!

I understand that this isn't a simple "adapter cable" scenario, thats why I was asking. I'm assuming the previously mentioned MCE2VGA adapter will cover all of my needs? I don't mind paying the cost if this is pretty much going to be fully compatible with all of my old CGA games. My CGA card doesn't have a composite out. I tried to find the Cirrus Logic GDA510/520 cards but can't find them anywhere, since they have hardware jumpers to put them into CGA mode. I'd rather not use the TSR utilities of other cards that would eat up more RAM.

Alternatively, there's also the SCART route (RGB output lacks Composite CGA, though)..
The CGA card is pretty much compatible to the signaling of what an SCART-equippred RGB monitor uses.

So all it needs is a little CRT monitor or LCD TV set with SCART connector and a homebrew adapter.
NTSC/PAL doesn't matter. Only 50/60Hz compatibility, which most of the TV models support.
A Japanese SCART TV may also work, but the wiring differs from Euro SCART.

XT/CGA laptop dissection

ZaphodsSecondHead wrote:

I'd rather not use the TSR utilities of other cards that would eat up more RAM.

I don't think the programs to switch to CGA mode are actually TSRs. They are just fire-and-forget utilities that send some commands to the card to switch it to a specific mode. So they just exit once the card is switched, and don't take any RAM.

Anyway, a real IBM CGA card is the 'gold standard' in terms of compatibility, and it also has a composite out. There should be plenty around, and shouldn't cost that much, so you could decide to get one of those at some point, if you choose the MCE2VGA road.

I second that, if the CGA isn't onboard, buying and installing a real CGA card would get you the real thing, incl. Composite output,
which can be handled by virtually all modern TV sets more or less.
Artifact colours might be a bit troublesome, but using an VHF/UHF modulator together with an old fashioned NTSC tube TV set will solve this.

Edit: Scali is right about the utilities. Atleast the ones I know, do only "flip" switches in the VGA card's silicon,
so they behave like a card equpped with a Motorola 6845 chip, for example.

Samples:

https://www.youtube.com/watch?v=7YtFhfny_oI
https://www.youtube.com/watch?v=cu88uKmqlEU

Jo22 wrote:

Alternatively, there's also the SCART route (RGB output lacks Composite CGA, though)..

Those are two different things and if your card supports it, you could do both...

SCART is a connector standard, not a signal standard. It originally supported RGB and composite, and was later updated to also support S-Video (because US didn't do RGB...) instead of RGB, but still at the same time as composite. So: if you do CGA RGBI -> RGB, you can still do CGA composite -> SCART composite as well, at the same time on the same connector 😉

RGB uses pins 15 (+13 GND), 11 (+9 GND) & 7 (+5 GND), Composite goes over 19 (+17 GND)

But...

When people talk CGA composite, they generally mean CGA NTSC composite. Most SCART TVs are PAL, which doesn't artifact the same way. This would only work if your card output NTSC composite and your TV understood it. Otherwise, MCE2VGA is still the way to go for CGA artefact colours.

Hm, I need some more English pratice again, it seems. 😅

What I meant to say:
Television Sets with SCART connectors can handle the 15KHz RGBI signals from the CGA card's DE9 connector almost directly.
There's a simplistic mixer circuit involved, and a few resitors here and there, but in general, it needs less modification than VGA's RGBHV input @31KHz

What I also meant to say:
PAL/NTSC colour coding doesn't matter if RGB is used on a PAL TV set. Or NTSC TV set.

Futhermore, there are two kinds of Composite CGA:
a) One uses the colour burst signal to generate colors on NTSC 60Hz TV sets.
b) The other one uses special patterns (lines, circles, etc) to trigger artifact colors on classic American tube TVs.
The artifact thing works best with lossy connections, such as Composte or RF.
Hence I recommended using a Composite-> RF conveter and an oldschool NTSC TV (cabinet made of wood, metal etc).

Edit: For completeness. I meant to point out that IBM's CGA followed signaling and resolutions of the Televisions standards of its time.
CGA was made on purpose compatible with them, so common thrid-party TVs and monitors could be used by end users.
And yes, it's true, Euro SCART can handle both RGB and CVBS (Composite), in fact, the monochrome (VBS) part of Composte is often used for syncronisation.
S-Video (falsely also known as S-VHS) came late to the party and was the old Chroma/Luma combo, in fact.
Albeit with a little bit different electrtical characteristic, if memory serves (have to check).
Because of that, and Euro SCART cables can either carry S-Video/Composite OR RGB/Composite, but not both.
Edit: Typos fixed.

Edit: One more. 😀

When people talk CGA composite, they generally mean CGA NTSC composite. Most SCART TVs are PAL, which doesn't artifact the same way.

Yup, 30 or 40 years ago, it was like that. If memory serves, SCART TVs of the last ~25 years or so were multi-norm all the way, though,
at least on the Composte terminals (not the tuner), since they were being made in the far east, anyway, were all standards
were used by each one's neighbour (China used to use PAL, Japan NTSC etc.)

A lot of PAL televisions can actually take a NTSC signal... Although not all TVs with a SCART connector are using RGB, sometimes it is just s-video or composite over SCART.

In the states, you have to either RGB mod a consumer set, or use a RGB to component transcoder. Since most dedicated CGA cards support composite or RF out, it usually just makes more sense to do that.

A little while ago I accidentally(!) discovered that my CGA could be forced to output a somewhat-valid PAL signal. Was writing some funny things to the CRTC registers when I accidentally programmed an incorrect value for Vertical Total.

This made the frame duration much longer, but surprisingly my dual-mode CRT TV still synced to it - of course, the frame-rate was slower, the image was vertically squashed, and there was no color, since the PAL-like scan rate obviously led the TV to expect PAL color encoding. But I've toyed with the idea of creating a TSR that would set these parameters for all video modes, and enable B&W PAL support for CGA. 😁

(FWIW, I think I ended up with something like ~52 Hz vertical, by my calculations; it could probably be made even closer to 50Hz.)