24 February 2009, 07:48 | #1 |
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What's the deal with pc's EGA rgb and composite outputs?
'mornin'!
I always had this question but bored to ask what's the deal with old EGA cards that output rgb and comosite? it seems that composite has more colors, 16 to be exact, instead of the 4 rgb ones... see here for some examples: RGB: Composite: anyone knows why? perhaps an link discussing the matter? thanks! Last edited by keropi; 24 February 2009 at 08:26. |
24 February 2009, 08:32 | #2 |
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This was a programming technique used at first by demo programmers and then widely adopted.
They noticed that if you placed certain colours next to each other they appeared a different colour (a colour not normally available) on composite output. Lots of games of the day on CGA and EGA used this technique of "Cross colour artifacts" sometimes known as smearing. http://en.wikipedia.org/wiki/Color_Graphics_Adapter |
24 February 2009, 08:40 | #3 |
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thanks alexh!!! I did forget about wikipedia!
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24 February 2009, 13:02 | #4 |
The 1 who ribbits
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thanks for that keropi & alexh, learn something new every day
I have clear memory of cga but never knew about the composit thing |
24 February 2009, 13:15 | #5 |
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Similar composite technique is used on the Apple II as well, only that the Apple II had 16 real colors four years before the CGA (In 1977). On RGB Apple 2 monitor the colors look sharp, on composite TV set more colors were visible, due to the composite artifacts.
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24 February 2009, 14:12 | #6 |
The 1 who ribbits
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yhear mori patterns are nothing new in the world of tv monitors
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24 February 2009, 14:39 | #7 | |
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Quote:
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24 February 2009, 20:23 | #8 |
Thalion Webshrine
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24 February 2009, 20:42 | #9 |
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Moiré.
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24 February 2009, 21:05 | #10 |
Thalion Webshrine
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I can never remember how to get that character..
ALT + (numeric keypad) 130 ? é Yup |
24 February 2009, 21:41 | #11 |
Just add brown sauce.
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I knew someone would just *have* to correct that
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24 February 2009, 21:44 | #12 |
Thalion Webshrine
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Either way it dont matter cos these colour smears are not moiré patterns
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24 February 2009, 22:49 | #13 |
Just add brown sauce.
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quite so, it's being clever with ntsc colour signal to make shiny new colours appear
there's a few games do this, I have a genuine cga card with video out somewhere, hopefully the 386 isn't too fast for these games |
25 February 2009, 14:25 | #14 |
The 1 who ribbits
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oh no the spelling police are out
and yes i know they arn`t Moiré patterns, its just a simmilar effect remember experimenting on old c64 in black and white on tv see if we could get some on the colours... results just something to muck about for the evening when a teenager ... |
27 February 2009, 10:20 | #15 | |
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Quote:
That's pretty cool though, getting 16 colors onscreen with the CGA card in 320x200 mode via color artifacting (or using 640x200 B&W mode to get a different set of 16 colors onscreen) - pic |
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27 February 2009, 10:25 | #16 |
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27 February 2009, 12:36 | #17 |
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27 February 2009, 12:43 | #18 |
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we had ALT-GR marking here in Greece too..
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27 February 2009, 13:21 | #19 |
The 1 who ribbits
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well on my keyboard
Alt-Gr + 4 = € Alt-Gr + e = é @ is shift ' between ; and # |
27 February 2009, 15:53 | #20 |
Just add brown sauce.
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I knew someone would post to correct about EGA cards not having video out too
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