Programmable ROM

PROMs are used in digital electronic devices to store permanent data, usually low level programs such as firmware or microcode.

Companies can keep a supply of blank PROMs in stock, and program them at the last minute to avoid large volume commitment.

These types of memories are frequently used in microcontrollers, video game consoles, mobile phones, radio-frequency identification (RFID) tags, implantable medical devices, high-definition multimedia interfaces (HDMI) and in many other consumer and automotive electronics products.

[2][3] The invention was conceived at the request of the United States Air Force to come up with a more flexible and secure way of storing the targeting constants in the Atlas E/F ICBM's airborne digital computer.

The patent and associated technology were held under secrecy order for several years while the Atlas E/F was the main operational missile of the United States ICBM force.

Examples include boot code, encryption keys and configuration parameters for analog, sensor or display circuitry.

As such OTP memory finds application in products from microprocessors & display drivers to Power Management ICs (PMICs).

Commercially available semiconductor antifuse-based OTP memory arrays have been around at least since 1969, with initial antifuse bit cells dependent on blowing a capacitor between crossing conductive lines.

Embedded controllers may be available in both field-erasable and one-time styles, allowing a cost saving in volume production without the expense and lead time of factory-programmed mask ROM chips.