BOff
BOff Switch off power to SCC and -5 volt supply if portA not in use The BOff procedure switches off power to the SCC and the -5 volt supply if serial port A is not in use. If the internal modem is installed, connected to port
B, and switched on, this procedure switches off power to the modem. Otherwise,
the BOff procedure switches off power to the serial driver chips, unless they are being used by port A.