The 74155 is a high-speed 8-bit bidirectional universal shift register that can be used as a bi-directional parallel-to-serial and serial-to-parallel converter. It is a synchronous device that includes 8 data-inputs (D0-D7), 8 data-outputs (Q0-Q7), a pair of enable lines (E1,E2), and necessary Clock, Reset, and Direction control lines. The 74155 is composed of three 8-bit storage registers, a parity generator and checker circuit, eight tri-state buffers, and five flip-flops. Both the serial-data output (Q7) and the output-enable line (E2) can be used as an 8-bit serial-data output port. Additionally, the 7405s can be cascaded and operated to provide a Higher order serial-data register.