ROM (Read Only Memory) - Short Definition:

ROM is a permanent memory of a computer that stores important instructions and does not lose data when the computer is turned off.

ROM (Read Only Memory) – Detailed Explanation

ROM (Read Only Memory) is a type of permanent memory in a computer that stores important data and instructions required to start and operate the system. It is called “read only” because the stored data can only be read and not easily changed.

ROM is non-volatile memory, which means it does not lose its data when the computer is turned off. The instructions stored in ROM are mainly used for booting the computer and controlling basic system functions.

When the computer is switched on, the CPU first reads the instructions from ROM to start the system. These instructions help to load the operating system into RAM so the computer can work properly.

There are different types of ROM:

1. PROM (Programmable Read Only Memory): Can be programmed only once.

2. EPROM (Erasable Programmable Read Only Memory): Can be erased and reprogrammed using ultraviolet light.

3. EEPROM (Electrically Erasable Programmable Read Only Memory): Can be erased and reprogrammed using electricity.

Therefore, ROM is an essential memory of a computer that stores permanent instructions and helps in the startup and basic functioning of the computer system.