Posted By
IstvanV
on 2017-10-16
08:36:50
|  Re: ep128emu is updated!
The lack of color attributes is because the video chip does not have a feature similar to bad lines in TED and VIC-II. In each raster line of a character, 2 bytes are read by the NICK chip from video memory, and 1 is reserved for the Z80. The text modes use one of the two bytes as the character code, and the other is read from the character set. A palette of 8 colors and other parameters of the current line are read during horizontal blanking.
There is a feature similar to ECM that uses the most significant bit(s) of the character code to select the upper or lower 4 colors of the palette in 4-color character mode, or one of the 4 pairs in 2-color mode, but this would not be enough to convert Exorcist without losing colors.
By the way, the Skramble port is already complete, there is a description (in Hungarian) and a few screenshots here: http://www.ep128.hu/Ep_Games/Leiras/Skramble.htm
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