12-15-2011, 02:49 PM
slenkar Wrote:this provides some explanation too
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Actually I think that's a bit misleading. The 'rainbow processor' only does: "a different colour on each pixel line, in a band twenty characters wide in the centre of the screen"
ZXodus does: "2 different colors for each bitmap byte (8x1) on each pixel line, in a band 18 characters wide, by 18 characters deep, relocatable (by changing the timings) but generally located in a window (with a one character border) on the top left of the screen"
Most rainbow processors use the POP / PUSH method for rapidly updating the attribute, but that only gets you 16 characters wide of individual colour. ZXodus uses LD / PUSH to get the extra two columns. Other modes use the full depth of the screen but because the CPU is held the whole time the attributes are being updated, by default ZXodus limits you to a 144x144 pixel window.
However, besides the extra colours, what really sets ZXodus apart is the simple tile mechanism used for updating the screen. The engine does handles all the scene updates for you. All you have to do is set which tiles (from a maximum of 256) you want to display in an 81 byte buffer.