INT 14 - MBBIOS - GET/SET OPTIONS
        AH = 09h
        AL = option byte (see below)
        DX = port number???
Return: AL = old option byte
SeeAlso: AH=00h"MBBIOS",AH=04h"MBBIOS",AH=10h"FOSSIL"

Bitfields for option byte:
 bit 0  transmit buffering enabled
 bit 2  hardware handshaking enabled
 bit 5  high-speed option enabled (see AH=00h"MBBIOS")
 other bits reserved

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