INT 45 - Acorn BBC Master 512 - "OSFILE" - READ/WRITE FILE OR DIRECTORY INFO

	AL = function
	    00h save block of memory as file
	    01h update directory entry for existing file
	    02h set load address for existing file
	    03h set execution address for existing file
	    04h set attributes for existing file
	    05h read directory
	    06h delete file
	    FFh load file
	DS:BX -> control block (see #03201)
Return: FLAGS destroyed
	AL = file type
	    00h not found
	    01h file found
	    02h directory found
	    FFh protected file
SeeAlso: INT 40"Acorn",INT 41"Acorn",INT 44"Acorn",INT 46"Acorn"