The MC74HCT259A is identical in pinout to the LS259. The device inputs are compatible with standard CMOS and LSTTL outputs. The HCT259A has four modes of operation. In the addressable latch mode, the data on Data In is written into the addressed latch. The addressed latch follows the data input with all nonaddressed latches remaining in their previous states. In the memory mode, all latches remain in their previous state and are unaffected by the Data or Address inputs. In the oneofeight decoding or demultiplexing mode, the addressed output follows the state of Data In with all other outputs in the LOW state. In the Reset mode all outputs are LOW and unaffected by the address and data inputs. When operating the HCT259A as an addressable latch, changing more than one bit of the address could impose a transient wrong address. Therefore, this should only be done while in the memory mode.
Output Drive Capability: 10 LSTTL Loads
Outputs Directly Interface to CMOS, NMOS, and TTL
Operating Voltage Range: 4.5 to 5.5 V
Low Input Current: 1uA
High Noise Immunity Characteristic of CMOS Devices