ROM is a read-only memory. The data in the ROM can only be read by the CPU, but cannot be modified. The CPU cannot directly access the ROM, the data has to be transferred to RAM first, and then the CPU can access that data from RAM.
The ROM stores instructions that the computer requires during startup (a computer startup process). The content in ROM cannot be modified. ROM is non-volatile memory, the data inside the ROM is preserved even if the CPU power is turned off.
What are the five Types of ROM?
ROM capacity is comparatively smaller than RAM, slower and cheaper than RAM. There are many kinds of ROM like the following:
- PROM: programmable ROM, can be modified only once by the user.
- EPROM: erasable and programmable ROM, the contents of this ROM can be erased using ultraviolet rays and the ROM can be reprogrammed.
- EEPROM: Electrically erasable and programmable ROM, can be electrically erased and reprogrammed some ten thousand times.