Best LCDs for retrocomputing - Was: Re: New *square* 1:1 26.5" LCD monitor 1920x1920

tony duell ard at
Tue May 17 15:56:17 CDT 2016

> 1. Some sites talk about e.g. arcade graphics as being "analog CGA" -- I
> was acquainted with these being called "analog RGB" but never saw "analog"
> and "CGA" together before.

I susepct it means that it's 3 analogue signals (one for each colour) at the 
CGA (== US TV, RS170) scan rates. As opposed, say, to VGA which is 3 
analogue signals with a rather higher horizontal scan rate.

> 2. There are computers knocking about with actual digital RGB signals, like
> the BBC Micro B (IIRC). What I forgot to make explicit in my question was

Yes, it dodes. The BBC micro has 3 TTL signals on the RGB connector. A
total of 8 possible colours.

> that I was asking about RGBI (+intensity), which AIUI is the same as CGA.

Normally yes. I don't see any reason why RGBI signals could not be used
at a different scan rate, but AFAIK no machine ever did.

> Now, I'm confused about point 1: did actual PCs with CGA have both digital
> (TTL) and analog signaling?

Not really. The original CGA card, and most clones, have a composite video
output too with NTSC-encoded colour, but that is not what you are asking


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