8255 Control and Status (Bit SET/RESET Mode – MSFLAG=0)

DIO Base+03h (8255-1), DIO Base+07h (8255-2) - (Read/Write)

SET	Bit set/reset individual command. 0 = reset 1 = set
BSEL	Port C bit select. 0 = bit 0 1 = bit 1 2 = bit 2 3 = bit 3 4 = bit 4 5 = bit 5 6 = bit 6 7 = bit 7
MSFLAG	Mode set flag. Selects the port configuration mode. 0 = Bit set/reset control register mode When MSFLAG is reset, this register is used to set/reset individual Port C Bits. 1 = Basic mode definition control register mode When MSFLAG is set, this register is used for direction and mode selection. NOTE: When the control word is read, the value of MSFLAG is always 1, implying basic control word information is being read.