INT 44 - Acorn BBC Master 512 - "OSARGS" - GET/SET FILE PARAMS FOR OPEN FILE
        AH = 00h
            AL = function
                00h get current filing system
                        Return: AL = filing system (see below)
                01h get address of commandline tail
                        Return: BX buffer filled with address of command tail
                                        in I/O processor address space
                                        (use INT 4A/AL=05h to retrieve)
                FFh flush all files onto secondary storage
        AH = file handle
            AL = function
                00h get sequential pointer for file
                01h set sequential pointer for file
                02h get length of file
        BX -> 4-byte data buffer
Return: BX buffer updated if appropriate
Note:   the commandline tail is terminated with a carriage return (0Dh)
SeeAlso: INT 41"Acorn",INT 45"Acorn",INT 4A"Acorn"

Values for filing system:
 00h none
 01h 1200 bps cassette
 02h 300 bps cassette
 03h ROM FS
 04h DFS
 05h ANFS/NFS
 06h TFS
 08h ADFS