These monolithic quadruple 2-input multiplexers with storage provide essentially the equivalent functional capabilities of two separate MSI functions in a single 16 pin package.
When the word-select input is low, word 1 (A1, B1, C1, D1) is applied to the flip-flops. A high input word select will cause the selection of word 2 (A2, B2, C2, D2). The selected word is clocked to the output terminals on the negative-edge of the clock pulse.
16 pin DIP. Manufactured by Texas Instruments. Sold in a package of 2.