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