INT 21 - VIRUS - "CoffeeShop" - INSTALLATION CHECK AX = 33DAh Return: AH = A5h if resident AL = 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. version SeeAlso: AX=33DB,AX=33DCh,AX=330Fh,AX=33E0h,AX=5643h"VIRUS"