The CD74HCT257E is a quad 2-input multiplexer which selects four bits of data from two sources under the control of a common Select Input (S). The Output Enable input (OE\) is active LOW. When OE\ is HIGH, all of the outputs (1Y-4Y) are in the high impedance state regardless of all other input conditions. Moving data from two groups of registers to four common output buses is a common use of the 257. The state of the Select input determines the particular register from which the data comes. It can also be used as a function generator.

Features:
Buffered Inputs
Typical Propagation Delay (In to Output) = 12ns at VCC = 5V, CL = 15pF, TA = 25?C
Wide Operating Temperature Range: ?55?C to 125?C
Balanced Propagation Delay and Transition Times
Significant Power Reduction Compared to LSTTL Logic ICs
4.5V to 5.5V Operation
Direct LSTTL Input Logic Compatibility, VIL = 0.8V (Max), VIH = 2V (Min)
CMOS Input Compatibility, Il 1?A at VOL, VOH

16 pin DIP. Manufactured by Harris.
A10964