Programmable ROM
Short for Programmable Read Only Memory, Programmable ROM or PROM is a computer memory chip capable of being programmed after it has been created. Once the PROM has been programmed, the information written is permanent and cannot be erased or deleted. A good example of a PROM is the computer BIOS.
PROM may also be referred to as field programmable read-only memory (FPROM) and was first developed by Wen Tsing Chow in 1956. When the PROM is created it ships with all bits reading as "1" and during the programming any bit that needs to be changed to a 0 is etched or burned into the chip.
Also see: EPROM, EEPROM, FPGA, Memory definitions, OTP, Programmable ROM programmer, ROM