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C02/include/apple2/screen.a02
2018-09-16 20:30:25 -04:00

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;Screen Control Assembly Lanuage Routines for Apple II
;Clear the Screen
CLRSCR: EQU $FC58 ;Applesoft Routine HOME
;Move Cursor To Home Position
CRSRHM LDA #0 ;Set Column to 0
TAY ;Set Row to 0
;and Fall into SETPOS
;Move Cursor to Specified Coordinates
SETPOS: STA $24 ;Store Column in CH
TYA ;Transfer Row to Accumulator
JMP $FB5B ;Exectute Monitor Routine TABV
;Get Cursor Position
GETPOS: LDA $24 ;Load Column from CH
LDY $25 ;Load Row from CV
RTS
;Get Screen Size
GETSIZ: LDA $21 ;Load Width from WNDWDTH
LDY $23 ;Load Height from WNDBTM
RTS