INT 21 - SKUDO - INSTALLATION CHECK                                             
	AX = 2C00h
	CX = 534Bh ('SK')
	DX = 5544h ('UD')
	BX = 4F21h ('O!')
Return: AX = 5349h ('SI') if installed
	    CH = version number
	    CL = subversion
Program: SKUDO is an antivirus TSR(Terminate and Stay Resident) A program which remains in memory after terminating in order to provide services to other programs or the user.  The name comes from the name of the DOS function call used to remain in memory after termination. by Jordi Mas