The previous slide showed that the receiver was enabled by the command SCON0 = 0x10, which sets the REN0 bit. Once enabled, received data will set the RI0 bit at the end of transmission (when the peripheral is sampling the stop bit time). If interrupts are enabled, the setting of RI0 will generate an interrupt and the interrupt service routine (ISR) will be executed. The ISR code will have to clear the flags and read the data in the receive buffer SBUF0.