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Amiga computer related discussion => Amiga Hardware Issues and discussion => Topic started by: amiga_3k on October 22, 2006, 11:32:11 AM
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Yesterday I picked-up the A4000T that was collecting dust at my parents' home. It used to have a PicassoIV in it but I gave that one to my brother a few years ago. It wouldn't be nice to take it away from him so I didn't. But now I've put myself into a proces looking at options available to connect the machine to a half-decent (preferable Apple, as it is sitting on my desk) monitor.
Going through the options ([1] getting an LCD TV with both SCART and VGA, [2] put the A2301 genlock in and continue to use the TV-card in the Mac, [3] getting a true multi-cync VGA monitor, [4] use one of those external scan-doublers used with gamecubes, [5] try and scoop a Picasso, Piccolo, Cybervision, Retina ... from eBay, [6] DIY scandoubler....).
I did some studying on the connectors available and one of the connectors available is the Amiga's 23 pin RGB. I noticed that there are digital RGB signals. Now a lot of Amiga's internals are being explained on the net but I didn't manage to find information on these signals. Does any of you know what kind of signals they are and how they can be used? Would it be possible to use these signals for playing games? Are those the signals that could be fed to the TTL connector at the back of (iirc) the 1084?
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times ago (on my A1000) i've tryed the digital RGB-I output tied with a 1084.
Crisp clear image BUT with only 4 colors. (or so)
Probably the RGBI out put of the Amiga port, is got before the digital>analogic conversion. No use for us :-(
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I'm not 100% sure on this - but I think the digital RGB is used for CGA 4-colour graphics displays only and so is totally useless for gaming. As far as I can remember, it is only recommended to use the analogue RGB input to the 1084s even though there are other inputs available.
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The RGBI signal is CGA compatible and its four bit output represents 16 colors (2^4).
Denise outputs 4 bits each for R, G and B that are input to the Vidiot DAC device and then output as analogue signals. The most signficant bits of each color are also output as DR, DG, DB plus the least significant bit from B as DI (intensity), doubling or halving the brightness of the output pixel. The colors are quite ugly, so the signal's not of much use:
(http://upload.wikimedia.org/wikipedia/en/2/2a/Alleycat.png)
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Sounds like it's an inheritance of the C64/C128 then. Too bad as I found a schematic for a scandoubler for TTL signals. Have to continue studying then.
Thanks for the quick replies.