The memory of computer plays a very important role on Computer system. Generally the Memory of computer can be divided into two types.
- ROM (Read Only Memory)
- RAM (Random Access Memory)
In this article we will give you the concept of ROM (Read Only Memory) and also tell you about the Three Types of ROM. I hope this article will be very helpful to you to get knowledge about ROM.
Concept of ROM
This is also a memory of computer, which is called read only memory (ROM). Again it is the ICs inside the PC that form the ROM. The storage of program and data in the ROM is permanent. The ROM stores some standard processing program supplied by the manufacturers to operate the personal computer. The ROM can only be read by the CPU but it cannot be changed. The basic input/output program is stored in the ROM that examines and initializes various equipment attached to the PC when the switch is made ON. The memories, which do not lose their content on failure of power supply, are known as non-volatile memories. ROM is non-volatile memory.
Types of ROM
PROM (Programmable Read Only Memory)
There is another type of primary memory in computer, which is called Programmable Read Only Memory (PROM). You know that it is not possible to modify or erase programs stored in ROM, but it is possible for you to store your program in PROM chip. Once the program is written it cannot be changed and remain intact even if power is switched off. Therefore program or instructions written in PROM or ROM cannot be erased or changed.
EPROM (Erasable Programmable Read Only Memory)
The stands for Erasable Programmable Read Only Memory, which over come the problem of PROM & ROM. EPROM chip can be programmed time and again by erasing the information stored easier in it. Information stored in EPROM exposing the chip for some time ultraviolet light and it erases chip is reprogrammed using a special programming facility. When the EPROM is in use information can only be read.
EEPROM (Electronically Erasable Programmable Read Only Memory)
This stands for Electronically Erasable Programmable Read Only Memory. EEPROM can be both erased and programmed electrical pulses. Since it can be both electrically written into and electronically erased, the EEPROM can be rapidly programmed and erased in circuit for reprogramming without removing them from the circuit board.
EEPROM is also called a non-volatile memory because when power is turned off the stored data in the EEPROM will not be eased or intact. New EEPROM have no data in it and usually have to program with a programmer before it can be retained for many years without a steady power supply.
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