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V9990

614 bytes added, 12:14, 22 December 2018
/* Reset */
* If using software reset and the reset is held, then reading or writing to the vram data port will cause the CPC to hang. I believe it's asserting /WAIT but I can't confirm.
 
=== Coordinates ===
 
* sx,sy,dx and dy use image space coordinates. This is 256, 512, 1024 or 2048 pixels width. Image space coordinates are not the same as the display coordinates and display width and height. Coordinate masking is based on image space coordinates.
 
* the image space height is computed from the vram size, bits per pixel and image space width based on an equation like this:
image space width in bytes = (image size width * image bpp)/8
height = vram size bytes / image space width in bytes;
 
For a vram size of 512 this gives image space heights of &1000,&800,&400,&200,&100 and &80.
=== VRAM ===
2,562
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