INT 21 - VIRUS - "Diamond-A", "Diamond-B" - INSTALLATION CHECK AX = D5AAh Return: AX = 2A55h if "Diamond-A" resident AX = 2A03h if "Diamond-B"-family 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. resident SeeAlso: AX=D000h,AH=D5h"VIRUS",AX=D5AAh/BP=DEAAh