2. Learning Objectives
• Introduce what computers are
• Understand how computers evolved
• How computer are categorised into broader
classifications
• Understand the complete architecture of a computer
• Understand various components of a computer
• Role of software and different types of software
• Broader steps required in software development and
implementation
• Emerging trends in the world of computers
3. 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.
4. •
Generation of Computers
First Generation – Vacuum Tubes (1939-1959): These computers were powered by thousands of vacuum
tubes. The Z1, Z3 and UNIVAC I are some examples. First generation computers were very slow,
consumed huge amount of power and had poor reliability accuracy.
• Second Generation – Transistors (1959-1965): These computers were made of transistors. Transistors
controlled the flow of electricity through the circuits. The use of transistors was a breakthrough in
technology that allowed computers to become physically smaller and more powerful, more reliable, and
even faster.
• Third Generation – Integrated Circuits (1965-1971): These computers used integrated circuits (ICs).
Integrated Circuits were also smaller, more efficient, and more reliable as compared to Vacuum tubes
and Transistors. Third generation computers used secondary storage devices, such as magnetic tapes,
magnetic disks, which are located outside the computer. The use of faster input/output devices
contributed to the enhanced utility of these computers for multiprogramming, wherein a number of
programs could be executed simultaneously by a single computer.
• Fourth Generation – PCs and VSLI (1971-1991): Fourth generation is the generation of Large-Scale
Integration (LSI) of chips with several thousand transistors and Microprocessors (based on Very-Large-
Scale Integration (VLSI)). Microcomputers were developed which allowed home and business users to
adapt computers for word processing, spreadsheet, file handling, graphics, and much more.
• Fifth Generation – Artificial Intelligence and Internet (1991 till date): The fifth generation computers are
more intelligent and have “thinking” power and capacity to take decisions. The concept of Artificial
Intelligence (AI) is being used in these computers and the processors used are known as `Knowledge
Processors’. Grand scale integration (GSI) happened, which allowed over thousand million transistors
embedded on a single chip. The GSI, allowed the computer to perform teraflop (trillion floating point
processing per second) of data. Fifth generation also introduced the concept of parallel processing,
which was the necessity of AI to happen.
5. Classification of Computers
• 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
7. 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.
8. Central Processing Unit (CPU)
Clock Micro-Processor Chip ROM Storage RAM Storage Input Output (I/O)
Interface
Control Bus
Address Bus
Data Bus
9. 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.
10. Memory
• Random-access memory (RAM) is that part of
primary storage where data and program
instructions are held temporarily while being
manipulated or executed.
• Read-Only Memory (ROM), as the name implies,
the contents of ROM can be read only; data
cannot be written into it.
• Cache Memory
• Dynamic random access memories (DRAMs)
• Synchronous DRAM (SDRAM)
11. Input Devices
• 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
– Light Pens and Digitizers
– Voice Recognitions
– Magnetic-Ink Character Recognition -Optical Scanners
– Web Camera
– Secondary Storage media like CD, DVD etc.
12. Output Devices
• 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.
13. Secondary Storage
• 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
14. Computer 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.
15. Type’s 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
16. Software Generations
• 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
17. Operating Systems
• 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
18. Control and Processing Programs
• Control programs manage the computer hardware and
resources. The major functions of these programs are:
– resource management
– data management
– job (task) management
• Processing programs are programs in the operating
system that provide a service to the user or the
programmer of the computer system. Examples
includes:
– language-translator programs
– utility programs
19. 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
21. Application Software
• Application software is any tool that helps in solving
end-user problems. It includes the generic productivity
software like spreadsheets, word processors, database
programs, email as well as custom and packaged
programs for payroll, billing, inventory and other
accounting purposes.
• There are different types of application software,
which can be classified as per broader classifications:
– Content Access Software
– End-User Software
– Enterprise Software
– Simulation Software
22. Industry Trends
• DNA COMPUTING
• Nanotechnology
• WEARABLE COMPUTING
• EMBEDDED COMPUTERS, Optoelectronic computers
and Quantum computing.
• Componentware
• Services-oriented architecture (SOA
• Autonomic Computing
• Grid Computing
• Cloud Computing
• Content and content
23. Summary
• Computer is an electro-mechanical device that helps is storing and processing data
for business purpose.
• All computers, irrespective of size and power, include a CPU, one or more input
units and output units, secondary storage and software.
• A central processing unit (CPU) is comprised of an arithmetic and logic unit (ALU), a
control unit, and a primary storage unit.
• Modern technology has put the ALU, the control unit, and in some cases, the
primary storage unit onto one integrated circuit called a microprocessor.
• There are several forms of primary storage, including semiconductor memory - RAM
and ROM.
• RAM is a volatile memory and are used primarily for temporary storage.
• ROM is non-volatile and is used for permanent storage.
• Data are transferred out of memory and into the ALU for processing by way of the
control, address, and data buses.
• The process of executing an instruction involves both an instruction cycle and an
execution cycle.
• The process of entering and translating it into machine readable form is called input.
• The process of translating machine-readable data into a human readable format is
called output.
24. Summary
• Primary storage is often inadequate because of its limited size and its volatility. To supplement
primary storage, secondary storage-a memory that is external to the computer and non-volatile.
• Three types of secondary storage media are magnetic tapes, disks, and optical media.
• A program, or software, is the series of instructions that directs the hardware to perform various
tasks.
• System software and application software are the two major categories of the software. Each of
these serves a different purpose.
• The set of programs that controls a computer system's hardware and provides services to users of
the system is called an operating system. It is composed of two types of programs: control and
processing programs. Control programs manage the computer hardware and resources. Processing
programs provide a service to the user or programmer of a computer system.
• In order to instruct a computer to perform specific tasks, a set of written codes is called a
programming language.
• Different types of Programming languages that exists can be categorised as: machine, assembly,
high-level, fourth-generation languages and object-oriented languages.
• An application package is a program that interacts with the system software to direct the computer
hardware to complete a task for the user. Commonly used application software are word processor,
spreadsheet, database, presentation tools, communication software, accounting and financial
software and project management.
• Software programs can be developed in-house or can be procured from the software vendor. While
procuring the software, different options that are available include shareware, freeware, open
source and public domain. One needs to be clear about these options and use them appropriately.
One also needs to be clear about the need of the user and the organisations objectives while
procuring the software.
