Programmable readonly memory (PROM) is a type of memory chip that can be programmed only once by the manufacturer or end user. PROM is often used in microcontrollers, industrial automation, and automotive applications. Other synonyms for PROM include "programmable memory," "one-time programmable (OTP) memory," "burned-in memory," and "non-volatile memory." Some alternatives to PROM are erasable programmable readonly memory (EPROM), electrically erasable programmable readonly memory (EEPROM), and flash memory. These types of memory chips can be programmed and erased multiple times, making them more flexible and convenient for certain applications.