MZ3500
(Subroutine lo send command and parameter to the GDC via the FIFO)
HL reg — First address of the command code oarametpr
B. reg — Q'ty of data.
C reg - 60H (graphic GDC), 70H (character GDC)
> FIFO Empty?
;
;Return if parameter not sent.
f FIFO Empty?
;PARAMETER — GDC
;Return when all parameters were sent.
RET
Example of graphic drawing by GDC
1) Dot display
0000 | 0001 | 0027 |
0028 |
|
|
VRAM
Example to display a dot on the fourth bit of the address
CSRW C 49H -COMMAND CODE
P1 01H — Low order one byte of the ab- solute address
P2 OOH — High order one byte of thp ah solute address
P3 30H - Dotaddress (dAD)
WRITE C 23H - COMMAND CODE
VECTE C 6CH - COMMAND CODE
- 49-
