INT 61 - VIRUS - "SEMTEX"/"Screen Trasher" - INT 21h SUBSTITUTE Note: the virusA program which attaches itself to other programs for the purpose of duplicating itself. Viruses often (but not always) contain harmful code which is triggered by some event, after a certain number of reproductions, or on a specific date. See also worm. copies the original INT 21h vector into INT 61h SeeAlso: INT 21/AH=00h,INT 21/AH=25h,INT 60"VIRUS",INT 6B"VIRUS"