Video (PC8801)

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Revision as of 18:15, 4 March 2016 by Zonk47 (talk | contribs) (Background/foreground component toggle)
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Port Name Function
0x52 Background Color Sets the background color of the screen. The color is an RGB composite.

If bit 3 (mask 0x8) = blue on if bit 4 (mask 0x10) = green on If bit 5 (mask 0x20) = red on

0x54 Toggle Background/Foreground color components Toggles background and foreground color components on and off

if 8-color mode {

 if bit 7 (mask 0x80) set, target is background color, else foreground
 if bit 6 (mask 0x40) toggle green component {
   GREEN ON if bits 1,2,3 (0x7) set, else OFF
 else toggle red and/or blue {
   BLUE ON if bit 1,2,3 set, else OFF
   RED ON if value written / 8 sets bits 1,2,3, else OFF

} else if monochrome mode, set foreground color {

 BLUE ON if bit 1 set (mask 0x1)
 RED ON if bit 2 set (mask 0x2)
 GREEN ON if bit 3 set (mask 0x4)


0x55-0x5b Palette Write Writes to the palette. The index written to is the difference between the port number and 0x54.