8-Bit Bidirectional Universal Shift Register with Parallel I/O High-Performance Silicon-Gate CMOS

The IN74HC299A isidenticalinpinoutto the LS/ALS299. The device inputs are compatible with standard CMOS outputs; with pullup resistors, they are compatible with LS/ALSTTL outputs.

The IN74HC299A features a multiplexed parallel input/output data porttoachieve full 8-bit handling ina 20 pin package. Due to the large output drive capability andthe 3-state feature, this device is ideally suited for interface with bus lines in a bus-oriented system.

Two Mode-Selectinputs and two OutputEnableinputs are used to choose the mode of operation as listed in the Function Table. Synchronous parallel loading is accomplished by taking both Mode Select lines, S1and S2, high. This places the outputs in the high impedance state, which permits data applied to the data port to be clocked into the register. Reading out of the register can be accomplished when the outputs are enabled. The active-low asynchronous Reset overrides all other inputs.

• Outputs Directly Interface to CMOS, NMOS, and TTL

• Operating Voltage Range:2.0 to6.0 V

• Low InputCurrent:1.0 µA

• High Noise Immunity Characteristic of CMOS Devices