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- DOSSEG
- .MODEL TINY
- .CODE
-
-
- ORG 100H
-
- BEG:
- JMP INIT
-
-
- OLD_ISR_OFFSET DW ?
- OLD_ISR_SEGMENT DW ?
-
-
- NEW_ISR PROC FAR
-
- PUSHF
- CALL dword ptr CS:[OLD_ISR_OFFSET]
- CMP AH,11H
- JNE OK
- MOV AH,10H
- OK: IRET
-
- NEW_ISR ENDP
-
- INIT:
- MOV AH,35H
- MOV AL,17H
- INT 21H
- MOV word ptr cs:[OLD_ISR_OFFSET],BX
- MOV word ptr cs:[OLD_ISR_SEGMENT],ES
- PUSH CS
- POP DS
- MOV DX,OFFSET NEW_ISR
- MOV AH,25H
- MOV AL,17H
- INT 21H
- MOV DX,OFFSET INIT
- INT 27H
-
-
- END BEG
-