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Old 03 February 2020, 19:28   #25
Photon
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Join Date: Nov 2004
Location: Eksjö / Sweden
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@Retro1234, HAM was another innovation the Amiga had, to allow truecolor pictures (as opposed to palettized images) without hefty RAM requirements. Computers were just beginning to get more than 64K of RAM; the Mac cost $2500 and had 128K. The Amiga 1000 doubled that, allowing another 256K expansion. Within 2 years, needs had been found that required 1MB to leave enough for the OS and programs. A HAM image would be exactly the size on file and in RAM as a 64-color picture! And this meant that an OS and a program to handle these pictures could fit in RAM.

HAM was the predecessor of the "hi-color" modes found on PC graphics cards in 1995. 4K colors vs ~29K colors. When hi-color cards came out PCs weren't powerful enough to run games in hi-color mode. This took another 4 years, and in 1999, PCs could run games in truecolor mode (~16M colors), but many lowered it to hi-color to not get a slow framerate.

I have never heard of "sliced HAM" before either. To me, it's PCHG. It's an image format that increases the number of colors in palettized pictures, but not in HAM pictures. Rather, it brings the total counted differing colors on-screen closer to 4K and reduces the artifacts, and leaves enough CPU left to run the OS and programs, on Amiga 1000 and up.

By comparison, you had to wait a few seconds to display a truecolor picture on your PC in 1992, due to the palette remapping; what you would see would be 256 colors. The same year, HAM was upgraded on AGA to 256K colors - much better than hi-color, but not as good as truecolor.
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