The SN74BCT29833 is an 8-bit to 9-bit parity transceiver designed for asynchronous communication between data buses. When data is transmitted from the A to B bus, a parity bit is generated. When data is transmitted from the B to A bus with its corresponding parity bit, the parity-error (ERR) output will indicate whether or not an error in the B data has occurred. The output-enable (OEA, OEB) inputs can be used to disable the device so that the buses are effectively isolated. A 9-bit parity generator / checker generates a parity-odd (PARITY) output and monitors the parity of the I/O ports with an open-collector parity-error (ERR) flag. ERR is clocked into the register on the rising edge of the CLK input. The error flag register is cleared with a low pulse on the clear (CLR) input. When both OEA and OEB are low, data is transferred from the A bus to the B bus and inverted parity is generated. Inverted parity is a forced error condition which gives the designer more system diagnostic capability. The SN74BCT29833 provides true logic.