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RTTYSB.ASM
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Assembly Source File
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1985-06-15
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1KB
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55 lines
PAGE,132
TITLE RTTY SUBROUTINES FOR BASIC PROGRAMS
SUBS SEGMENT PUBLIC 'CODE'
ASSUME CS:SUBS,DS:NOTHING
PUBLIC SCROLL
SCROLL PROC FAR
;************************************************
;
; ON ENTRY PARAMETERS PASSED ARE THE POINTERS TO
; STARTING ROW (INTEGER), ENDING ROW (INTEGER)
; AND NUMBER OF COLUMNS (INTEGER)
;
;************************************************
PUSH BP
MOV BP,SP ;GET THE PARAMETERS FROM THE STACK AREA
MOV SI,[BP]+10 ;GET PARM 'A'
MOV CH,[SI] ;STARTING ROW FOR SCROLL
MOV SI,[BP]+8 ;GET PARM 'B'
MOV DH,[SI] ;ENDING ROW FOR SCROLL
MOV SI,[BP]+6 ;GET PARM 'C'
MOV DL,[SI] ;NUMBER OF COLUMNS
DEC CH ;CONVERT THE ROWS AND COLUMNS TO
DEC DH ;VALUES REQUIRED BY THE
DEC DL ;VIDEO-OUT INTERRUPT
MOV CL,0 ;START AT LEFT HAND SIDE OF SCREEN
MOV AX,CS ;POINT TO A NEW STACK AREA
CLI
MOV SS,AX
MOV SP,OFFSET STACK_TOP
STI
PUSH BP ;SAVE THE ORIGINAL STACK POINTER
MOV BH,7 ;ATTRIBUTE OF THE BLANKED LINE
MOV AX,601H ;SCROLL UP LEAVING ONE LINE BLANK
INT 10H ;INVOKE BIOS VIDEO ROUTINES
POP BP ;RETRIEVE THE ORIGINAL STACK POINTER
CLI
MOV AX,DS ;RESTORE THE ORIGINAL SS:SP
MOV SS,AX
MOV SP,BP
STI
POP BP
RET 6 ;RETURN TO BASIC
PAGE
DW 50 DUP(?)
STACK_TOP LABEL NEAR
SCROLL ENDP
SUBS ENDS
END