ROM (Read Only Memory)

Read Only Memory(ROM)

It is the memory where the startup program (set of instructions) is stored, called BIOS (Basic Input Output System) ROM, when we press the start button on the CPU, program stored in ROM starts running the Operating system.

BIOS ROM  chip on a motherboard

Classification of ROM

I. PROM (Programmable Read Only Memory)

PROM is a device that can be programmed by the user using special equipments, called PROM buses.
Once the PROM is programmed that data cannot be change.

II. EPROM(Erasable PROM)

In this ROM , it was possible to re-program the driver or IC. EPROM is two types

1.EEPROM(Electrically Erasable PROM)

Uses high voltage for erasing the program

2.UVPROM(Ultra Violet PROM)

Uses ultraviolet rays to erase program, for that EEPROM contains a small indow, it is normally protected from light using a sticker.

III. Flash ROM

Modern computers use Flash ROM, in this ROM software is used for re-programming.

So there is no need to remove the IC from motherboard for programming.