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M Z 3500
(Subroutine to send command and parameter to the GDC
via the FIFO)
HL reg — First address of the command code. parameter tsble.
B. reg ~- Q'ty of data.
C reg - 60H (graphic GDC), 70H (Character GDC)
> FIFO Empty?
; COMMAND — GDC
; Return if parameter not sent.
? F I F O Empty?
; PARAMETER — GDC
;
Return when all Parameters were sent.
RET
Exarnple of graphic drawing by GDC
1) Dot display
0000
0028
0001
0027
VRAM 16-bit
structure
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 the ab-
solute address
P3
30H - Dot address (dAD)
WRITE C
23H - COMMAND CODE
VECTE C
6CH - COMMAND CODE
- 49-
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