The SCON0 register is used to select the serial port operation mode and enable/disable UART reception. The mode of operation is configured by programming the S0MODE bit. For 8-bit UART mode, set the bit to 0. TI0 and RI0 are the Transmit Interrupt Flag and Receive Interrupt Flag, respectively. The REN0 bit is used to enable the receiver to start accepting data from another UART peripheral.