What is ROM?
ROM (Read-only memory) is a permanent storage medium that stores start-up programs like operating system programs. These programs are loaded to the computer when the computer is switched on. Read-Only Memory is also called nonvolatile memory because it never loses its contents or data.
Read-Only Memory (ROM) holds instructions that the computer needs to operate.
Whenever the computer’s power is turned on, it checks ROM for directions that help its start-up, and for information about its hardware devices.
Types of ROM
There are basically three types of ROM used in computers.
Programmable ROM (PROM)
Once a Programmable ROM has been programmed, its content can’t be changed anymore. It’s used in one time programmable devices. This type of ROM mainly used in non-programmable video game consoles, mobile phones, implantable medical devices, and high definition multimedia interfaces.
Erasable Programmable ROM (EPROM)
It’s almost similar to the PROM, but this type of ROM can be erased by exposure to strong ultraviolet light. That’s why it is also known as Ultraviolet Erasable Programmable ROM (UV EPROM)
Electrically Erased Programmable ROM (EEPROM)
EEPROM is quite similar to the EPROM, the difference is it can be erased electrically and can rewrite electrically and the burning process is reversible by exposure to electric pulse. This is the most flexible type of ROM. Nowadays EEPROM is commonly used in BIOS (Basic Input/Output System).