This basic NAND gate has two inputs and one output per channel and 4 total channels. The chip’s internal circuitry looks at both of the input lines and makes a decision whether or not the output should be switched on (HIGH) or turned off (LOW).

NAND Gate logic:
• If both inputs are LOW, the output will be HIGH
• If one of the inputs is HIGH and the other is LOW, the output will be HIGH
• If both inputs are HIGH, the output will be LOW