Video (PC8801)

From Data Crystal
Revision as of 22:15, 4 March 2016 by Zonk47 (talk | contribs) (Background/foreground component toggle)
Jump to navigation Jump to search
Port Name Function
0x30
0x34
0x35
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

0x53
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.
0x5c-0x5f