maxtherabbit wrote on 2024-08-26, 13:23:

"slightly fuzzy" more like "looks like dog shit smeared on a screen"

🤣, yeah something like that. but in 16 colors for a few games

dionb wrote on 2024-08-26, 12:05:

We're all talking digital CGA from the DE-9 connector here, but the original IBM CGA also output analog composite, which was admittedly slightly fuzzy, but a ) is far better supported by newer devices (I have TFT screens with native composite in as well as any old CRT TV able to take NTSC composite input) and b ) quite a few games made use of the 'features' of NTSC composite to generate more colours than natively supported by CGA. Unless you intend to do serious work requiring you to spend long times looking at text on the screen, I'd recommend going down the composite route rather than the digital one.

MDA was always recommended for serious work, poring over text or figures, even over the first few years of VGA, until monitors got a lot better. But if you are flitting between action games and text adventures, I guess TTL RGB CGA is it.

I came across ScrapComputing's MCE Blaster, a Pi Pico-based CGA/EGA/MDA to VGA adapter. Not available to buy though, you'll have to build your own.
AIUI it uses the RP2040's PIOs to sample the digital RGB signal (via level shifters), then outputs an analogue RGB signal at VGA timings via a 6-bit R-2R DAC.

renejr902 wrote on 2024-08-26, 13:36:

maxtherabbit wrote on 2024-08-26, 13:23:

"slightly fuzzy" more like "looks like dog shit smeared on a screen"

🤣, yeah something like that. but in 16 colors for a few games

Perhaps switching to a 7" vga could crisp it right up ?

BitWrangler wrote on 2024-08-26, 15:10:

dionb wrote on 2024-08-26, 12:05:

We're all talking digital CGA from the DE-9 connector here, but the original IBM CGA also output analog composite, which was admittedly slightly fuzzy, but a ) is far better supported by newer devices (I have TFT screens with native composite in as well as any old CRT TV able to take NTSC composite input) and b ) quite a few games made use of the 'features' of NTSC composite to generate more colours than natively supported by CGA. Unless you intend to do serious work requiring you to spend long times looking at text on the screen, I'd recommend going down the composite route rather than the digital one.

MDA was always recommended for serious work, poring over text or figures, even over the first few years of VGA, until monitors got a lot better. But if you are flitting between action games and text adventures, I guess TTL RGB CGA is it.

douglar wrote on 2024-09-03, 16:05:

renejr902 wrote on 2024-08-26, 13:36:

maxtherabbit wrote on 2024-08-26, 13:23:

"slightly fuzzy" more like "looks like dog shit smeared on a screen"

🤣, yeah something like that. but in 16 colors for a few games

Perhaps switching to a 7" vga could crisp it right up ?

CGA always had been sort of a toy.. That's why home users kept using it.
TV compatibility was most important feature, but there's just so much you can do with 200 lines.
Even on a monochrome video monitor, the low resolution can be made out.
Alternative was MDA, before Hercules and EGA had hit the scene.

In mid-80s, third-party manufacturers tried to figure out a way out of this dilemma and created enhanced, CGA compatible graphics adapters.
They often used 640x400 pels resolution, which allowed lossless up-scaling of CGA graphics. Native graphics modes had existed, too.
Text-mode used higher resolution fonts, providing fine characters in 80x25.

Today, Toshiba laptops and the Olivetti M24/AT&T 6300 probably come to mind when we think of 640x400, but they were merely most popular.
The Wyse WY-700 (supported by PCem) did use a fixed 1280x800 resolution, even for 320x200 and 640x200 CGA modes.
Another one is Galaxy Uni-Screen CGA / Galaxy Uni-Screen EGA by GalaGraph Ltd. (from 1987) it did CGA in 640x400, but had an 1024x768 native mode and could mix graphics.
Other 640x400 adapters can be found in this topic over here: Obscure enhanced CGA clones with 640x400 monochrome mode

Edit: I just recently saw CGA cards on eBay that could be switched to an "high-res" mode via jumper, which did output 640x400 resolution.
Probably using non-CGA compatible timings. The card was an Hercules/CGA clone card.

Edit: The CGA/HGC cards with an 82C426 chip can do 640x400 monochrome mode, as well.
Dosdays has more information on this.

Edit: What made CGA appealing over other graphics mode was application support and PC BIOS support.
Even the professional IBM PGC did feature an optional CGA emulation. CGA was sort of a baseline configuration.
A lowest common denominator, as my math teacher would say. The very basic thing everyone would agree upon.

I'm not sure that board can take TTL CGA just like that. It's an arcade upscaler. CGA in arcade context is not IBM PC CGA.

Get a dedicated PC upscaler, if you can buy secondhand MCE2VGA, if you can't get a new MCE2HDMI packaged with HDMI to VGA dongle, if you have DIY experience check out MCEblaster on github, it has like $5 worth of components around Pi Pico and can be powered from the PC.

If you're looking for an alternative, Necroware designed an MCE MDA/CGA/EGA To VGA Adapter and this seller already assembled the parts into a kit: https://www.ebay.com/itm/135009807467

Main caveat to this adapter is that it needs a monitor that supports 15Khz, or a scaler to bump that up.

There's also an interesting Github project, Graphics Gremlin.

"The Graphics Gremlin is an FPGA-based ISA video card specifically designed to emulate certain old video standards.
This initial release emulates the original IBM PC monochrome graphics adapter (MDA) as well as the original IBM color graphics adapter (CGA)."

"For both MDA and CGA, the Graphics Gremlin has a VGA port that can deliver video running
at standard (31KHz) frequencies that are well supported by LCD monitors, VGA-to-HDMI converters, and USB capture devices."

https://github.com/schlae/graphics-gremlin

So if you don't need "Composite CGA" (NTSC artifact colours), any CGA clone will do just fine.
Personally, though, I find that composite video is most important/unique feature of CGA.
640x200 in high resolution with/without colour carrier.

Here in Europe, the PAL land, many 1980s PCs with built-in CGA did provide the latter mono video via RCA/Cinch/Phono connector.
And the image quality was excellent on a green or amber monitor, albeit a bit low res due to the 200 line limitation.

So it's merely partially true that composite video sucks.
Because the underlying monochrome signal with sync pulses is high quality.

But even the blurry artifact colours of old NTSC standard have their place.
They make games look more mysterious, more organic and are a tribute to the Apple II days.

PS: On a personal note I often think that CGA monitors should tried to be hacked to accept either analogue RGB or composite.
That way, they could be made work with a VGA card and an RGB cable and a DOS TSR (to set 15 KHz timings needed by an RGB video monitor).

This would get away with the 16 colour limit and unleash the old tubes' true potential.
MCGA games would look beautiful on a hacked IBM 5153, for example.

Unfortunately, I do merely have a vague idea how this works in practice. A new PCB for IBM 5153 or similar monitors would be needed, maybe.
Or the filter stages for absolute RGB colours must be bypassed on the original boards. Composite would need more, um, intelligence in the circuitry.

Thanks for every answers guys. I still thinking about all these options you told me, its really appreciated