In order to initiate a transmit cycle, the processor must first check to see if the peripheral is busy. The TI0 flag can be used to accomplish this as it indicates when the transmit buffer is empty. Once the processor verifies the transmit buffer is empty, it writes to SBUF0 to start the transfer. As soon as data is written to the buffer the transmission begins. The TI0 flag is set at the end of character transmission and indicates “transmit buffer empty.” This condition occurs after the 8th bit is shifted out of the peripheral. In some applications where a buffer of data is required to be transferred, it is useful to set up the firmware such that writing a 1 to the TI0 bit would initiate an ISR cycle at which point the ISR can buffer pointers and the flags in order to cycle through all of data.