CPU and Output Devices with Example for IBPS RRB Officers Selection Exam

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As Shown in Figure at a Basic Structure of CPU

Basic structure of CPU

CPU (Central processing unit)

It is a principal part of any digital computer system, generally composed of the main memory, control unit, and arithmetic-logic unit.

CPU – Heart of the Computer

CPU Process:

  1. Fetch the Instruction
  2. Interpret the Instruction
  3. Fetch the Data
  4. Process the Data
  5. Write the Data
CPU Process Are Given in Image

Storage Unit or Memory Unit:

Diagram Shows a Storage Unit or Memory Unit

Primary Memory or Main Memory

Primary storage also known as main storage or memory, is the area in a computer in which data is stored for quick access by the computer՚s processor.

Memory Heirarchy


Register is one of a small set of data holding place that are part of the computer processor. A register may hold an instruction, a storages address, or any kind of data (such as a bit sequence or individual characters) . Some instructions specify registers as part of the instruction.

This Diagram Shows Types of RAM

1. RAM (Random Access Memory) – it՚s a type of data storage used in computers that is generally located on the motherboard.

This type of memory is volatile and all information that was stored in RAM is lost when the computer is turned off.

There are two types of Random access memory

  • Dynamic RAM – dynamic indicates that the memory must be constantly refreshed (reenergized) or it will lose its contents.
  • Static Memory – A computer memory that contains fixed information and retains and retains its programmed state as long as the power is on.

2. ROM (Read Only Memory) – Once data has been written onto a ROM chip, it cannot be removed and can only be read. Unlike main memory (RAM) , ROM retains its contents even when the computer is turned off. ROM is referred to as being nonvolatile.

DEFINITIONA form of data storage that can be accessed randomly at any time, in any order and from any physical location.A form of data storage that cannot be easily altered or reprogrammed.
STANDS FORRandom Access MemoryRead-only memory
USERead data quickly to run applications. It allows reading and writing.Stores the program required to initially boot the computer. It only allows reading.
VOLATILITYVolatile (contents are lost when the device is powered off)Non-volatile (contents are retained even when the device is powered off) .

There are three types of Read only Memory (ROM)

  • PROM – PROM stands for Programmable Read Only Memory. This from of ROM is initially blank. The user or manufacturer can write data/program on it by using special devices.

However, once the program or data is written in PROM chip, it cannot be changed. PROM chip becomes unusable.

  • EPROM – EPROM stands for Erasable Programmable Read Only Memory. This from of ROM is also initially blank. The user or manufacturer can write program or data on it by using special devices. Unlike PROM, the data written in EPROM chip
  • EEPROM – EEPROM stands for Electrically Erasable Programmable Read Only Memory. This kind of ROM can be written or changed with the help of electrical devices. So data stored in this type of ROM chip can be easily modified.

3. Cache:

A cache is a place to store something temporarily in a computing environment. Cache memory, also called CPU memory, is random access memory (RAM) .

This Diagram Shows Process of Cache Memory

Memory units

Storage capacity is expressed in terms of Bytes. The Data is represented as binary digits (0s and 1s)

Hierarchy – Bit < Nibble < Byte < KB < MB < GB < TB < PB < XB < ZB < YB

GB = Gigabyte

TB = Terabyte

PB = Petabyte

XB = Exabyte

ZB = Zettabyte

YB = Yottabyte

Disk Storage

  • 1 Bit = Binary Digit
  • 8 Bits = 1 Byte
  • 1000 Bytes = 1 Kilobyte
  • 1000 Kilobytes = 1 Megabyte
  • 1000 Megabytes = 1 Gigabyte
  • 1000 Gigabytes = 1 Terabyte
  • 1000 Terabytes = 1 Petabyte
  • 1000 Petabytes = 1 Exabyte
  • 1000 Exabytes = 1 Zettabyte
  • 1000 Zettabytes = 1 Yottabyte
  • 1000 Yottabytes = 1 Brontobyte
  • 1000 Brontobytes = 1 Geopbyte

American Standard Code for Information Interchange (ASCII) is the standard code the computer industry created to represent characters (more than 64 characters)

New units as

Kibibyte = 1024 bytes

Mebibyte = 1024 KiB