Datasheet
dual decade counter;
dual 4-stage
binary counter
the SN54/74LS390 and SN54/74LS93 each contain a pair of high-speed 4-stage ripple counters. Each half of the LS390 is partitioned into a divide-by-two section and a divide-by five section, with a separate clock input for each section. the two section can be connected to count in the 8.4.2.1 BEC code or they can count in a biquence sequence to provide a square wave