SN74LS77 PDF File ( Datasheet )

4-BIT D LATCH The TTL, MSI SN54 , 74LS75 and SN54 , 74LS77 are latches used as temporary storage for binary information between processing units and input , output or indicator units. Information present at a data (D) input is transferred to the Q output when the Enable is HIGH and the Q output will follow the data input as long as the Enable remains HIGH. When the Enable goes LOW, the information (that was present at the data input at the time the transition occurred) is retained at the Q out