In a general sense, a lockout chip is a chip within an electronic device to prevent other manufacturers from using a company's device to perform certain functions.

A notable example is the lockout chip found in Nintendo's Nintendo Entertainment System (called 10NES), designed to prevent "unlicensed" manufacturers from creating games for the console.^[1] The presence of the chip forced unlicensed companies to raise the price of each cartridge (due to a bypass chip having to be added to the cartridge), and allowed Nintendo a foothold for a lawsuit.

Lockout functions are commonly used in printers to prevent the use of third-party ink or toner cartridges.^[2]