ROM (Read-Only Memory) is a type of computer memory which stores data and programs that can not be changed, or “written to.” ROM is non-volatile memory, meaning that its content is retained even when power is switched off. Despite the name ROM, many types of ROM allow data to be written at least once, but the process is generally considered to be too slow and/or expensive to be used for large amounts of data or frequent changes.
ROM is typically used to store the computer’s initial boot instructions and other firmware, such as the System BIOS and Many embedded systems use ROM to store their operational code, to execute their software.
There are several types of ROM in use today, including Mask ROM, PROM, EPROM, EEPROM, and Flash ROM. Mask ROM is a hard-coded ROM which is programmed and fabricated with the necessary data during the manufacturing process (instead of being written after the chip is fabricated). PROM is a programmable ROM which is written-once, using Hi-Voltage to burn the data into the chip. EPROM is an Erasable Programmable ROM which is erased with ultraviolet lights. EEPROM is an Electrically Erasable ROM which allows data to be re-written slowly and repeatedly. Flash ROM is a type of EEPROM which allows re-writing data very quickly.
ROM is a vital part of the computer system, as it houses all the instructions that the system needs when booting up. It is generally considered to be an outdated form of data storage, as it is slow and most home computers rely on faster forms of memory, such as RAM, for system operations. Despite its aging nature, ROM still finds a home in many new computers, as it is the most reliable form of data storage available and protects the system from being modified by malicious software or viruses.
