what is rom and its types?
Read-Only Memory (ROM).
Rom stands for Read only Memory.The instructions in ROM prepare the Pc to be used .These instructions can only be read but can't be changed or deleted. It is impossible to write down new Information or Instructions into the ROM. ROM stores data and instructions permanently. When the facility is transitioned , the instructions stored in ROM aren't lost. Therefore ROM is called non-volatile memory. The information in ROM is stored already by the manufacturer. When the pc is switched on, the instructions within the ROM are automatically loaded into the memory of the pc ROM contains a little set of instructions called ROM BIOS. BIOS stand for Basic input/output system. These instructions tell the computer how to access hard disk, find operating system and load in it RAM. Different types of ROM are mentioned below.
PROM stands for Programmable Read Only
Memory.
This form of ROM is initially blank. The user or manufacturer can write
data and programs on it using exclusive devices. The user can write data and instructions/information
on it only once. If there is any error in writing the instructions or information the error cannot be removed from PROM. The chip becomes unusable.
EPROM stands for Erasable Programmable
Read-Only Memory.
This form of ROM is initially blank. The user or manufacturer
can write data and programs on it using exclusive devices. The data and programs written on it can be erased
with exclusive devices using ultraviolet rays. The
user then can write new program there on.
EEPROM (Electronically Erasable
Programmable Read-Only Memory).
In this memory user can erase and write
instructions with the assistance of electrical pulses. If there's any error in
writing the instructions the user can erase the contents electronically. The
contents of EEPROM can be modified easily.