VOGONS


First post, by retardware

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I will be moving overseas soon, thus I do not want to keep my CRTs.
But I want to still be able to use my Hercules card.

So I am looking for a converter MDA->VGA.
The Serdashop MDA->VGA converter is quite expensive and ugly.

Back in the 1990s there already existed converters made by a company named "COVID", which manufactured various video processing hardware.

This is the "COVID Ezpix PC" converter from around 1994.
file.php?mode=view&id=118845

It allegedly does just the same things that MCE2VGA does.
And it is period-correct and being sold much cheaper than MCE2VGA.

However, it has only 4 BNC outputs. RGB+Sync.
That was fine for CRTs with BNC inputs back then.
But, can it run on 15-pin VGA monitors with separate H/V and possibly different signal levels?

So my question:
Do you have a manual or even a schematic, so one can find out whether it is possible to adapt or mod the converter?

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Reply 2 of 7, by bloodem

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konc wrote on 2021-09-09, 07:07:

What an unfortunate time to search about something that contains "covid" in its name

Exactly what I was thinking... 🤣

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Reply 4 of 7, by bestemor

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I actually tried one different version of these (came NiB from the US,many many MANY moons ago).
- It was a CGA/EGA to VGA version though. Wanted to see if it could be used on my IBM 5150, hoping to be able to use a 'modern' LCD to replace my ancient 12 inc CRT monitor...
(used a 5-BNC to VGA cable for the output)

But maybe I did something wrong, cause the picture was NOT any good at all....
Granted, I do not remember much now, but it was a preliminary test on a ISA EGA card on a slot1 PC.
Just to see if I at ALL could get this thing to work.

And the (white) text at POST was all green and stuff, and the picture was generally somewhat distorted/noisy. Not good.
Still, these converters must have been good for 'someting', or they would not exist, right ?
(seing the miserable results, I then concluded this was useless, and packed it away)

Reply 5 of 7, by retardware

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Thank you, @wiretap and @bestemor!

The RGB2HDMI seems hard or not available for sale (found only offers from Poland, specifically for Amiga use).
And reading the report of @bestemor, I think it might be not worth to speculate on a satisfiable experience with that (optically nice) COVID converter.
So I think it is safe to assume that the FPGA solution of serdashop (which many in Germany use and say it works just fine) will be an easy, albeit ugly and not "period correct" solution. I think I'll just stick it behind the monitor using double-sided adhesive tape, to avoid cluttering the space with its ugly appearance 😀

Anyway, I still wait a bit for other hints at possible alternatives before I buy the serdashop converter.

Reply 6 of 7, by Imperious

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MDA, EGA, CGA are digital video signals.

Those cheap EGA/CGA to VGA adaptors were designed for arcade boards that use analog signals and will not convert digital signals to VGA.

You need a more expensive solution, or try to find someone selling the RGB2HDMI that uses a PiZero. I just made one myself but haven't tested yet
with CGA or EGA, just my Amstrad CPC 464 as I built an analog board as well that plugs in.

Whatever You get make sure You research it as many of these converters have pros and cons. For instance the RGB2HDMI will not convert
my Atari 2600 with RGB board as it only supports up to 40 colours or so, Atari 2600 128 colours.

https://github.com/hoglet67/RGBtoHDMI/wiki

Atari 2600, TI994a, Vic20, c64, ZX Spectrum 128, Amstrad CPC464, Atari 65XE, Commodore Plus/4, Amiga 500
PC's from XT 8088, 486, Pentium MMX, K6, Athlon, P3, P4, 775, to current Ryzen 2600.

Reply 7 of 7, by dionb

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Those 'Covid' Ezpix PC 85 devices seem to be readily available and cheap (if you live in US, shipping elsewhere is killing as usual) - but do they do digital RGB or just analog? Given the same input does VGA or whatever comes over that DE-9 connector, I'd suspect analog only.

Composite sync isn't really an issue, there are generic solutions to to separate that out, things like this:
sync-signal-separator.gif?resize=485%2C292