ROM

ROM:

ROM is a permanent  memory it is also known as a volatile memory  because ROM retain the information  in  it even the computer is switched off ROM stores the computer configuration information which the computer needs all the time. We can not  write anything inside ROM so, it is called Read Only Memory.

There are three types of ROM

PROM

EPROM

EEPROM

PROM stands for the programmable Read Only Memory . It can be modified only once. PROM allows to write microcode programs using a special device called PROM.

EPROM  stands for Erasable Programmable Read Only Memory. It can be erased and programmed  multiple times.

EEPROM: EEPROM stands for electrically Earasable Programmable Read Only Memory. It can be erased  and programmed repeatedly with the help of electrical pulses.