Read-only memory (ROM)

One type of memory is that, Read Only Memory, as it is not erased when the system is switched off. It is also called BIOS ROM. Basic input and Output System. It is made by Complementary metal–oxide–semiconductor (CMOS) programmers or data stored in this memory can’t be altered or modified.

Types of ROM PROM (Programmable Read Only Memory) : Stored programs can be Read for special applications.

EPROM (Erasable Programmable Read Only Memory) memories are PROMs that can be deleted. These chips have a glass panel that lets ultra-violet rays through. This is why this type of PROM is called erasable.

EEPROM (Electrically Erasable Read Only Memory) memories are also erasable PROMs, but unlike EPROMs, they can be erased by a simple electric current, meaning that they can be erased even when they are in position in the computer.