INT 14 - MX5 Extended FOSSIL(Fido/Opus/Seadog Standard Interface Layer)  A standardized API for performing serial I/O, originally used by the Fido and Opus bulletin- board software and Seadog bulletin-board mailer, but now in wider use. - INSTALLATION CHECK
	AX = E006h
	BX = 0000h
Return: BX = 4D58h ('MX') if installed
	    AH = major version
	    AL = minor version
SeeAlso: AX=E000h,AX=E001h,AX=E005h,AX=E007h