HCF40208B

The HCC40208B (extended temperature range) and HCF40208B (intermediate temperature range) are monolithic integrated circuits, available in 24-lead dual in-line plastic or ceramic package and plastic micro package. The HCC/HCF40208B is a 4 x 4 multiport register containing four 4-bit registers, write address decoder, two separate read address decoders, and two 3-state output buses. When the ENABLE input is low, the corresponding output bus is switched, independently of the clock to a high-impedance state. The high-impedance third state provides the outputs with the capability of being connected to the bus lines in a bus-organized systemwithout the need for interface or pull-up components. When theWRITE ENABLE input is high, all data input lines are latched on the positive transition of theCLOCKand the data is entered into the wordselected bythewriteaddress lines.WhenWRITE ENABLE is low, the CLOCK is inhibited and no new data isentered. In either case, the contents ofanyword may be accessed via the read address lines independent of the state of the CLOCKinput.