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PAGE ,132
; Install a custom Interrupt 23 (Ctrl-C exception) handler
;
; Public domain by Bob Stout
;
; Requires MASM 5.1 or later or equivalent
;
; Assemble with: MASM /Mx /z ...
; TASM /jMASM /mx /z ...
% .MODEL memodel,C ;Add model support via command
;line macros, e.g.
;MASM /Dmemodel=LARGE
.DATA?
_origvec dd ?
_newvec dd ?
.CODE
;
; This is our actual ISR
;
myint23:
call dword PTR _newvec ;call our handler
iret
;
; Call this to install our ISR
;
ins23 PROC USES AX BX DS ES, offs:WORD, segm:WORD
mov ax,3523h ;get old vector...
int 21h
mov word PTR _origvec,bx
mov word PTR _origvec+2,es ;...and save it
mov ax,offs ;load handler offset...
mov word PTR _newvec,ax
mov ax,segm ; & segment into _newvec
mov word PTR _newvec+2,ax
push cs ;get myint23 segment in DS
pop ds
mov dx, OFFSET myint23 ;install myint23 in int 23h
mov ax,2523h
int 21h
ret
ins23 ENDP
;
; Call this to uninstall our ISR
;
redo23 PROC USES AX BX DS
mov dx, word PTR _origvec ;restore original vector
mov ds, word PTR _origvec+2
mov ax,2523h
int 21h
ret
redo23 ENDP
end
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