Routines
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49777: Scroll Screen Up
Used by the routine at ProcessCharacterInput.
ScrollScreenUp 49777 PUSH HL Stash HL, DE and BC on the stack.
49778 PUSH DE
49779 PUSH BC
49780 LD HL,20608 HL=20608 (screen buffer location).
49783 LD DE,20576 DE=20576 (screen buffer location).
49786 LD A,8 A=8.
ScrollScreenUp_0 49788 PUSH HL Stash HL and DE on the stack.
49789 PUSH DE
49790 LD BC,128 BC=0128.
49793 LDIR LDIR.
49795 POP DE Restore DE and HL from the stack.
49796 POP HL
49797 INC H Increment H by one.
49798 INC D Increment D by one.
49799 DEC A Decrease A by one.
49800 JR NZ,ScrollScreenUp_0 Jump to ScrollScreenUp_0 if A is not equal to 8.
49802 LD HL,20704 HL=20704 (screen buffer location).
This entry point is used by the routine at ScrollScreenDown.
ScrollScreenUp_1 49805 LD B,36 B=36.
49807 LD C,1 C=1.
49809 LD A,32 A=32.
ScrollScreenUp_2 49811 CALL PrintCharacter Call PrintCharacter.
49814 DJNZ ScrollScreenUp_2 Decrease counter by one and loop back to ScrollScreenUp_2 until counter is zero.
49816 POP BC Restore BC, DE and HL from the stack.
49817 POP DE
49818 POP HL
49819 RET Return.
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