SESSION 3

LEARNING OBJECTIVES

Introduction to computers Understand how computers evolved Computer classifications The architecture of a computer The role of different types of software Emerging trends in the world of computers

WHAT IS A COMPUTER SYSTEM?

A Computer is an electronic device that operates under the control of a set of instructions that is stored in its memory unit.

A computer accepts data from an input device and processes it into useful information which it displays on its output device.

A computer system is a collection of hardware and software components that help in accomplish many different tasks.

Hardware consists of the computer itself, and any equipment connected to it. Hardware includes all of the physical, tangible parts of a system - such as central processor, memory, display devices, storage media and printer etc.

Software is the set of instructions for controlling the hardware devices, instructing computers to transform data into information and many other information processing tasks.

Computers are available in different shapes, sizes, processing capacities and weights, due to these different shapes and sizes they perform different types of jobs and have different functionalities.

Supercomputer Mainframe Micro-computer Notebook PDAs

COMPUTER ARCHITECTURE

MOORE’S LAW

The storage density of integrated circuits on a silicon chip doubles in every year.

The computing power doubles in every 1.5 years for a given cost.

COMPONENTS OF A COMPUTER SYSTEM

Central Processing Unit (CPU): The “brain” of the Computer - this is where the actual computing is done. The CPU usually controls all the operations of the computer.

Memory: An electronic storage medium used to hold the program which instructs the CPU and other components of the computer.

Input/Output Devices: These are the link between man and machine. They depend on the processing requirements.

Input/ Output Interfaces: These are `middleman` between the CPU and the I/O devices. They provide the actual hard-wired control of the I/O devices, according to the commands that are issued by the CPU.

Programs (Software): Without the program, a computer is a dumb machine that sits there and draws current. The program coordinates the operations of the computer in order to perform some desired process.

COMPONENTS OF A COMPUTER Central Processing Unit: The central processing unit

is the most important part of a computer system. It is also referred as a "brain" of the computer.

Arithmetic and Logic Unit: The arithmetic and logic unit (ALU) is the part of the CPU where all mathematical and logical functions are performed.

Control Unit: The control unit interprets any instruction it receives from memory and directs the sequence of events necessary to execute the instruction.

Primary Storage: The primary storage unit refers to the internal storage of the computer, where programs and their data are stored.

Bus: A bus is simply an electrical path on which data can flow from point to point within a circuit.

COMPUTER ARCHITECTURE

Hardware Processors : That unit where data processing is

performed. Memory (Primary): Located on the circuit board

and is volatile. For example RAM Memory (Secondary) : Any memory that is not on

the main circuit board. For example Floppy disks, CDs, Hard disks, Digital Versatile Disks (DVDs) etc.

COMPUTER ARCHITECTURE

Software Systems software Application software Freeware Malware (Virus, Worms, Spyware) Security (IDS, Firewall, Anti viruses)

Peripherals Input devices: Monitor, Keyboard, mouse Output devices: Printers (dot matrix, inkjet,

Laser) Input-Output devices: Touch screen

MEMORY

RAM ROM

Secondary storage is the non-volatile memory that supplements main memory by providing data storage that is permanent and typically of much greater capacity than main memory. It is less expensive, as compared to the primary storage and is usually used for storage of large amounts of data for permanent storage. Secondary storage is also used for storing backups, or copies, of data and programs that are frequently required at a later date. Commonly used secondary storage devices are:

Magnetic Tapes Magnetic Disks Optical Disks

INPUT DEVICE

An input device is a peripheral device through which data are entered and transformed into machine-readable form. Some of the commonly used input devices are:

Keyboards Mouse Digitizers Voice Recognitions Magnetic-Ink Character Recognition -Optical

Scanners Web Camera Secondary Storage media like CD, DVD etc.

OUTPUT DEVICE

An output device is a peripheral device that accepts data from a computer and transforms them into a usable form, thus allowing the computer to communicate information to humans or other machines. Commonly used output devices are:

Printers Plotters Monitors and Terminals Speakers Secondary Storage media like CD, DVD etc.

SOFTWARE

The set of instructions used to control hardware and accomplish specific tasks are called software. Computer software provides the logic that drives computer hardware.

The major functions of software are to: manage the computer resources of the

organisation; develop tools that human beings can utilize

to take advantage of these resources; and act as an intermediary between stored

information and organisations.

TYPES OF SOFTWARE

System Software: System software directly interacts with the hardware and comprises of programs that manage the hardware components.

Application Software: Programs that help the user, the system software, and the hardware work together to solve end-user problems are application software.

Applications software can be purchased in stores and is called packaged or commercial software.

Packaged software can be purchased, or in some cases, it is available free of cost called Freeware

SOFTWARE EVOLUTION The first generation (1940s) of software was the machine

language, which used the 0s and 1s of binary language and was the only way in which programmers could communicate with the computer.

The second generation (1950s) of software was the development of assembly language - using mnemonic codes.

The third generation (1950-70s) of software was the development of first high level languages - more sophisticated extensions of assembly language and used more English like sentences.

Fourth generation (1970s) of software development was of packaged software programs that perform limited functions. These programs reduced the need of writing and compiling small routine applications.

Fifth generation (1990s) of software development was of integrated software, animations software and multimedia technology. Natural languages is also treated as part of fifth-generation languages

PROGRAMMING LANGUAGES

Machine Languages Assembly Languages High level Languages 4th generation Languages (SAP R/3,

PeopleSoft HRMS, SQL)

PROGRAMMING APPROACHES

Top Down Approach (Procedural Language) Bottom Up Approach (Object oriented

Language)

UTILITY SOFTWARE

Language Translators : Compilers and Translators.

Loaders and Linkers:

TYPES OF SYSTEMS SOFTWARE

Assemblers Interpreters Compilers Linkers Loaders

OPERATING SYSTEM An operating system is a set of programs that controls and

supervises a computer system’s hardware and provides service to application software, programmers, and users of a computer system.

The purpose of an operating system is to manage the hardware resources efficiently and to provide an interface between the hardware and an application program and end user.

An operating system helped in increasing the efficiency of a CPU, it decides which resources will be used, which programs will run, and how the programs will be translated into machine language.

Major Goals of Operating System: To hide details of hardware by creating abstraction To allocate resources to processes (Manage resources) Provide a pleasant and effective user interface

TYPES OF OPERATING SYSTEMS

Single-User Operating System Multi-user Operating System Multiprogramming Operating System Time-sharing Operating System Multiprocessing Operating System Virtual-storage Operating System Virtual-Machine Operating System Mobile Operating System

TRENDS

Nanotechnology Wearable computing Quantum computing Grid Computing Cloud Computing