INT 2F U - DR-DOS 5.0 NLSFUNC - PREPARE CODE PAGE
        AX = 14FFh
        BX = code page
Return: AX = ???
        ZF set if AX=0000h
Notes:  DR-DOS 5.0 NLSFUNC returns CF set and AX=0001h if AL was not 00h, FEh,
          or FFh on entry.
        passes codepage preparation request to each character device supporting
          the generic IOCTL call
SeeAlso: AX=14FEh,INT 21/AX=440Ch,INT 21/AX=6602h

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