More Color Computer Entry posted by potatohead December 21, 2009 1,238 views Share More sharing options... Followers 0 First attachment is 256 color swatch pattern. 640 pixel mode, 4 colors, composite display, palette entries are 0, 16, 32, 64. (all monochrome) Value start with 0 in upper left, counting up to 15 at lower left, 16 next column over, filling to 256 at lower right.
andym00 123 Posted December 22, 2009 Oohh That looks nice... These are grabbed on a capture card or they're real TV photos ? I'm not quite sure.. Resolution says capture card to me, but something about it also says photo of screen, probably the little speckles in the top left of each square.. Quote Link to comment
Serguei2 1,219 Posted December 22, 2009 Hmmm. I'm not sure. Are you talking about Radio-Shack Color Computer 3 or IBM PS2? Quote Link to comment
potatohead 1,603 Posted December 23, 2009 It's a capture from a PC capture card. The one I have is really nice, capturing a full 720x486 NTSC frame, with great color resolution. This is the Radio Shack Color Computer 3. That display was created by NTSC artifacting, where smaller pixels result in colors on composite video displays, due to signal resolution. On Atari machines, for example, the 320 pixel mode, results in two easy to obtain artifact colors. Odd pixels are one color, even pixels are another color. The Color Computer 3 has a 640x200x4 color display! When running on a composite monitor, or in this case, a PC capture card, that is one byte per pixel at 160 pixels, which is the signal limit of the Color Computer. Some computers, like the C64, output a better color signal that has more resolution, and those computers won't do the hi-color trick, but will show more detail on a TV. The CoCo 3 was built with high resolution graphics, intended for a RGB monitor, and had TV output capability compatable with the older Color Computer 1 and 2. That design decision brings 256 colors to the CoCo 3, because of how the analog signal works. The display above is a 160x200x256 color display, one byte per pixel, where each byte value results in a different color on the screen. A few of these actually are the same, but I'm not going to worry about that. A 512K CoCo 3 should be able to render some very nice retro game titles in great color, without fancy interrupts and such being needed for the display. It's a full on bitmap! I thought this was cool in the very early 90's and never did anything with it. Recently, some discussion with other CoCo owners triggered me to get this out there for discussion and some programming fun. So it's a capture. The speckles are because my CoCo seems to have a rather noisy video output. Might be all CoCos do this. The little speckles are variances in the video output. Again, I think that's my CoCo showing some age... Quote Link to comment
Serguei2 1,219 Posted December 24, 2009 Awesome. I didn't know CoCo 3 could display 256 colors on screen. Many CoCo3 screenshots I saw in Radio-Shack catalogs have a least 16 colours. Did somebody release 256 colours games for CoCo 3? Quote Link to comment
potatohead 1,603 Posted December 25, 2009 There have been no games released. The 160x200x256 mode is an artifact color mode, like what happens on Atari and Apple, when pixels are drawn to the screen connected through a composite video signal. Tandy designed the machine to run a 16 color display, and gave it display interrupt capability to use it's 64 stock color palette, like Ataris do by changing color definitions mid-screen. In the very early 90's I had a CoCo 3, and figured out the machines would do 256 colors at 160x200 resolution and never did much with it. Was just barely on the Internet at that time, and so never posted it. I don't think many people knew about this, because the machine also shipped with RGB capability and that's where all the attention went. TV Graphics were largely ignored. --until now! Heh! Recent retro computing discussions sparked this memory and the mode is seeing some use. One user has pictures encoded now. I don't have a disk or disk emulation yet, or I would have already uploaded them! Can't wait to see the pictures. I'm kind of hoping some development can happen, maybe emulator support. The CoCo 3 does not have sprites, but it's got a good, fast CPU, and some hardware scrolling assist. IMHO, the machine should be able to do some great retro style games with a lot of color. It's a very powerful and well designed little computer. Quote Link to comment
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