Int 21H [2.0] Function 35H (53) Get interrupt vector

Obtains the address of the current interrupt-handler routine for the specified machine interrupt.

Call with:

AH = 35H

AL = interrupt number

Returns:

ES:BX = segment:offset of interrupt handler

Note:

Together with Int 21H Function 25H (Set Interrupt Vector), this function is used by well-behaved application programs to modify or inspect the machine interrupt vector table.

Example:

Obtain the address of the current interrupt handler for hardware interrupt level 0 (divide by zero) and save it in the variable oldint0.

oldint0 dd ? ; previous handler address

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mov ah,35h ; function number

mov al,0 ; interrupt level

int 21h ; transfer to MS-DOS

; save old handler address

mov word ptr oldint0,bx

mov word ptr oldint0+2,es

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