Path: utzoo!censor!geac!torsqnt!news-server.csri.toronto.edu!cs.utexas.edu!samsung!sdd.hp.com!zaphod.mps.ohio-state.edu!julius.cs.uiuc.edu!psuvax1!psuvm!cunyvm!mtus5!tomiii
From: TOMIII@MTUS5.BITNET (Thomas Dwyer III)
Newsgroups: comp.os.msdos.programmer
Subject: stealing an interrupt
Message-ID: <90351.150210TOMIII@MTUS5.BITNET>
Date: 17 Dec 90 20:02:10 GMT
Organization: Computing Technology Services, Michigan Technological Univ.
Lines: 49

Hi there.  Would some kind soul please tell me why my machine hangs when
I run this TSR?  What am I doing wrong?

------ Code Begins ------

INT_NUM equ     9h

code    segment
        org     0100h
        assume  cs:code,ds:code,es:code

start:
        mov     ah,35h                          ; Get int vector
        mov     al,INT_NUM
        int     21h

        mov     word ptr [old_int+2],es         ; Save old vector
        mov     word ptr [old_int],bx

        mov     ah,25h                          ; Set int vector
        mov     al,INT_NUM
        mov     dx,offset new_int
        int     21h

        mov     dx,50h
        mov     ax,3100h
        int     21h


new_int proc    far
        jmp     short go

old_int dd      ?

go:
        jmp     [old_int]                       ; Jump to old int routine
new_int endp


code    ends
        end     start

----- Code Ends ------

Thank you,
Thomas Dwyer III                        Email: tomiii@mtu.edu
Network Programmer                             tomiii@mtus5.BITNET
Computing Technology Services           Voice: (906) 487-2110
Michigan Technological University       Fax:   (906) 487-2787