Path: utzoo!utgpu!news-server.csri.toronto.edu!cs.utexas.edu!sdd.hp.com!zaphod.mps.ohio-state.edu!rpi!ceej From: ceej@pawl.rpi.edu (Chris J Hillery) Newsgroups: comp.sys.amiga Subject: Re: DCTV from digital creations Message-ID: Date: 13 Sep 90 05:45:51 GMT References: <4290@crash.cts.com> <1990Sep10.003304.4678@bushido.uucp> <403@cbmger.UUCP> Organization: Rensselaer Polytechnic Institute, Troy NY Lines: 55 peterk@cbmger.UUCP (Peter Kittel GERMANY) writes: >In article ceej@pawl.rpi.edu (Chris J Hillery) writes: >> >>Isn't DCTV the box which gets 256 screen colors by intercepting a 640x400 >>16 color screen and combining each pair a pixels (4 bits each) into one >>8-bit pixel? I know there is a box like this. In this case, all well and >>good, you get 256 out of 16million (I think) colors, but only in 320x400 >>(or variations... not 640 mode at any rate). This could be a consideration. >Ah, is that really true? Just recently I wondered that such a device >would be even simpler when built into the Amiga replacing the Video >Hybrid chip. But I found for myself that this wouldn't be such a big >advantage, because you don't get 256 colors! It's more limited in choice >of possible color combinations than the ExtraHalfBright mode. I tried >to imagine an algorithm to make up a palette for a certain set of >needed colors for a certain image. But I found no solution. Nono, I don't think you understand what I was saying. Lemme try a li'l numerical example... On the Amiga's Screen: pixel 0: F pixel 1: 5 1111 0101 <- binary representation of pixels 0 and 1 in memory DCTV (or whatever the box was) gets this, and combines them to: On the DCTV output screen: pixel 0:F5 11110101 so this pixel is color F5, or 245. Then it sends this to the monitor, using whatever color happens to be in palette slot 245. Again, of course, this means you get 2-for-1, or 320 width, resolution. But, you do have 256 colors on the screen wherever you want them (ie, color 246 somewhere else would have a pixel of color F followed by a pixel of color 6; duplicate Amiga colors != duplicate output colors). This is why the actual picture the Amiga thinks its showing in 640x400 looks so weird. StdDisclaimer: Again, I don't know if DCTV is this device. I just know this device exists. I THINK that's what the DCTV is. Ceej aka Chris Hillery ceej@pawl.rpi.edu >Well, perhaps they found one for the DCTV. >But question to all: Is this really the trick they use? >-- >Best regards, Dr. Peter Kittel // E-Mail to \\ Only my personal opinions... >Commodore Frankfurt, Germany \X/ {uunet|pyramid|rutgers}!cbmvax!cbmger!peterk