exp92.asm

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CODE     SEGMENT  PARA
         ASSUME CS:CODE,DS:CODE

NEW_INT0        PROC    FAR
                PUSH    AX
                PUSH    BX
                PUSH    CX
                PUSH    DX
                PUSH    SI
                PUSH    DI
                PUSH    BP
                PUSH    DS
                PUSH    ES
                STI

                JMP     START
OLD_INT0        DD      ?
STRING          DB      'Divide by zero!$'
START:          PUSH    CS
                POP     DS
                MOV     DX,OFFSET STRING
                MOV     AH,9
                INT     21H

                MOV     AH,2
                MOV     DL,07H
                INT     21H

                MOV     AH,0
                INT     16H

RETURN:         CLI
                POP     ES
                POP     DS
                POP     BP
                POP     DI
                POP     SI
                POP     DX
                POP     CX
                POP     BX
                POP     AX
                IRET
NEW_INT0        ENDP

H_LEN           EQU     $-NEW_INT0

MAIN            PROC    FAR
                MOV     AX,CS
                MOV     DS,AX

                MOV     AH,35H
                MOV     AL,0            ;GET  INT 0 ADDR
                INT     21H

                MOV     WORD PTR OLD_INT0,BX
                MOV     WORD PTR OLD_INT0+2,ES

                MOV     AH,25H
                MOV     AL,0
                MOV     DX,OFFSET NEW_INT0      ;DS=CS
                INT     21H

                MOV     DX,(H_LEN+15)/16+10H
                MOV     AX,3100H
                INT     21H
MAIN            ENDP
CODE            ENDS
                END     MAIN