Topic summary
XNOR
Extracted from the Wikipedia article XNOR gate.
Hardware description
XNOR gates are represented in most TTL and CMOSIC families. The standard 4000 series CMOS IC is the 4077, and the TTL IC is the 74266 (although an open-collector implementation). Both include four independent, two-input, XNOR gates. The (now obsolete) 74S135 implemented four two-input XOR/XNOR gates or two three-input XNOR gates.