These routines read and write the colour palette. They take a 5 byte parameter block:
Parameter block
| XY+ | Content | Read call | Write call |
|---|---|---|---|
| 0 | Logical colour | Logial colour | |
| 1 | Physical colour | Current mapping | Required mapping |
| 2 | Reserved for future expansion | Set to 0 | |
| 3 | Reserved for future expansion | Set to 0 | |
| 4 | Reserved for future expansion | Set to 0 |
Write Palette
The OSWORD 12 write palette call performs the same task as a VDU 19 command which can be used from machine code using OSWRCH.
The advantage of using this OSWORD call rather than the conventional VDU route is that there is a significant saving in time.
Another advantage is that OSWORD calls can be used in interrupt routines while VDU routines cannot.