The MM54C173 MM74C173 TRI-STATE quad D flip-flop is a monolithic complementary MOS (CMOS) integrated circuit constructed with N- and P-channel enhancement transistors The four D-type flip-flops operate synchronously from a common clock The TRI-STATE output allows the device to be used in bus-organized systems The outputs are placed in the TRI-STATE mode when either of the two output disable pins are in the logic ``1'' level The input disable allows the flip-flops to remain in their present states without disrupting the clock If either of the two input disables are taken to a logic ``1'' level the Q outputs are fed back to the inputs and in this manner the flip-flops do not change state