Code: Select all
LD A,0C6H
CALL 0DDCH
LD HL,0D3E9H
LD DE,0D3EAH
LD BC,27H
LD (HL),0D0H
LDIR
LD BC,27H
LD (HL),43H
LDIR
LD DE,0E27DH
LD HL,0E008H
VBLANK: LD A,(0E002H)
RLA
JR C,VBLANK
LD A,$7F
HBLK1: CP (HL)
JP C,HBLK1
LD A,(DE)
LD A,$7F
INC DE
INC DE
INC DE
INC DE
INC DE
HBLK2: CP (HL)
JP C,HBLK2
LD A,(DE)
...
...
...
We couldn't really get this to work though. It'd be good if anyone knows the 80A hardware enough to give us some hints whether it is possible to even split pixel lines alternately (using the video scroll available on the 80A through $E27D etc). Here we wait for HBLNK, we change the scrolled area of the screen, then wait for HBLNK again (after burning some cycles using INC DE five times). And so on.
psmart : perhaps you have an idea of the possibility of achieving this?