)
Call VCD entry point with:
	EDX = function number
	    0000h get VCD version
		Return: CF clear
			AH = major version
			AL = minor version
	    0001h get ???
		Return: CF clear
			AX = bit mask of ???
	    0002h get ???
		CX = COM port number
		Return: CF clear
			DX:AX -> ???
	    0003h set ???
		CX = COM port number
		DX:AX -> new ???
		Return: CF clear
	    0004h acquire COM port
		AX = ???
		CX = COM port number
		Return: CF clear
			AX = ???
			EBX = ???
			DX = ???
	    0005h release COM port
		CX = COM port number
		Return: CF clear
	    0006h ???
		Return: CF set
			AL = 00h
	    else
		Return: CF set
			EAX = FFFFFFFFh
Note:	these functions are apparently only available from the system VM,
	  returning CF set and EAX=FFFFFFFFh otherwise
SeeAlso: #02651,#02653