Programmable ROM

Updated: 10/01/2023 by Computer Hope

PROM or programmable ROM (programmable read-only memory) is a computer memory chip that can be programmed once after it is created. Once the PROM is programmed, the information written is permanent and cannot be erased or deleted. PROM was created by Wen Tsing Chow in 1956. An example of a PROM is a computer's BIOS (basic input/output system) in early computers. Today, PROM in computers has been replaced by EEPROM (electrically erasable programmable read-only memory).


A programmable ROM is also called a FPROM (field programmable read-only memory) or OTP (one-time programmable) chip.

When the PROM is created, all bits read as "1." During the programming, any bit needing to be changed to a "0" is etched or burned into the chip using a gang programmer. Below is an example of a gang programmer from Advin that programs multiple ROM (read-only memory) chips at one time.

Gang programmer

If a PROM has an error or needs an update, the chip is discarded, and a new PROM is created, replacing the old chip. A variation of the PROM is an EPROM (erasable programmable read-only memory), which can be erased and reprogrammed without being replaced.


These devices are also sometimes called a programmable ROM programmer and a PROM blaster.

Computer acronyms, EEPROM, EPROM, FPGA, Hardware terms, Memory terms, OTP, ROM