These devices contain two independent 4-input NAND gates.
The SN5420, SN54LS20, and SN54S20 are characterized for operation over the full military range of -55°C to 125°C. The SN7420, SN74LS20, and SN74S20 are characterized for operation from 0°C to 70°C.
Manufactured: 1975 week 13