Video (PC8801)
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| Port | Name | Function |
| 0x30 | ||
| 0x34 | ||
| 0x35 | ||
| 0x52 | Background Color | Sets the background color of the screen. The color is an RGB composite.
|
| 0x53 | ||
| 0x54 | Toggle Background/Foreground color components | Toggles background and foreground color components on and off
if 8-color mode {
if bit 8 (mask 0x80) set, target is background color, else foreground
if bit 7 (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.
if port 0x31 bit 6 (0x20) set {
if bit 7 (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 {
BLUE ON if bit 1 set (mask 0x1)
RED ON if bit 2 set (mask 0x2)
GREEN ON if bit 3 set (mask 0x4)
}
|
| 0x5c-0x5f |