INT 41 - Acorn BBC Master 512 - "OSGBPB" - MULTI-BYTE GET/PUT
	AL = function
	    01h put bytes sequentially
	    02h put bytes, ignoring sequential pointer
	    03h get bytes sequentially
	    04h get bytes, ignoring sequential pointer
	    05h get media title and boot option
	    06h get current device and directory
	    07h get current library and device
	    08h search directory
	DS:BX -> control block (see #03199)
Return: CF clear if successful
	CF set on error
	AL = 00h if operation attempted
	AL unchanged if unsupported function
SeeAlso: INT 40"Acorn",INT 42"Acorn",INT 43"Acorn"


Format of BBC Master control block:
Offset	Size	Description	(Table 03199)
 00h	BYTE	file handle
 01h	DWORDDoubleword; four bytes.	 Commonly used to hold a 32-bit segment:offset or selector:offset address.	pointer to data in either I/O processor or Tube processor
 05h	DWORDDoubleword; four bytes.	 Commonly used to hold a 32-bit segment:offset or selector:offset address.	number of bytes to be transferred
 09h	DWORDDoubleword; four bytes.	 Commonly used to hold a 32-bit segment:offset or selector:offset address.	transfer address