| Z88 Developers' Notes | ||
|---|---|---|
| Contents | Contents of System Calls | |
OS_Sci, alter screen information
RST 20H, DEFW $D406
IN:
A = reason code
SC_LR0 ($01) LORES0 (512 bytes granularity, 13 bits width)
SC_LR1 ($02) LORES1 (4K granularity, 10 bits width)
SC_HR0 ($03) HIRES0 (8K granularity, 9 bits width)
SC_HR1 ($04) HIRES1 (2K granularity, 11 bits width)
SC_SBR ($05) screen base (2K granularity, 11 bits width)
B = 0, get pointer address (address is not set)
B <> 0, set pointer address with BHL = new pointer address
and HL is truncated according to screen granularity
OUT:
Fc = 0 BHL = old pointer address
Registers changed after return:
A..CDE../IXIY same .FB...HL/.... different
Notes:
These hardware registers should not be altered unless the programmer knows what he is doing. Please refer to the "Hardware section".
Bugs: