Computer system and it class 1

Computer System Software Hardware Computers Today
CSE 101: Introduction to Computer Science
Lesson 1: An Overview on Computer Systems
Muhammed Tawfiq Chowdhury
Lecturer
Department of Computer Science and Engineering
Northern University Bangladesh
tawfiq.nub@gmail.com

Outline
1 The Parts of The Computer System
Computer System
The Parts of Computer System
2 Software Brings The Machine to Life
Software
Operating System
Operating System Services
Application Software
3 Hardware
Looking Inside the Machine
How Computer Process Data?
4 Computers Today
Classification of Computers

Outline
Computer System
Software
Operating System
3 Hardware
4 Computers Today
4

Computer System
What is a computer?
A computeris an electronicdevicewhich-
◮ can respond to a specific set of instructions in a well-
defined manner.
◮ canexecute apre-recordedlist ofinstructions(aprogram).

Computer System: Characteristics
◮ Quick data-input,information-retrieval,andstoredata.
◮ Accurate results computation.
◮ Quick processing of arithmetic and logic operations.
◮ Continuousandpersistentwork-ability.
◮ Promptdecisionmaking.
◮ Communicability with other computers through networks.

A complete computer system include four distinct parts.
1 Software
2 Hardware
3 Data
4 User

Software
Software-alsocalledprograms -consists oforganizedsetsof
instructions for controlling the computer.
◮ Someprogramsexistforthecomputer’suse,tohelpitmanage
its own tasks and devices.
◮ Otherprogramsexistforthe user,andenable the computerto
perform tasks for you, such as creating documents.
Hardware
A computer's hardware consists of electronic devices; the
parts you can see and touch. The term “device" refers to any
piece of hardware used by the computer, such as a keyboard,
monitor, modem, processor, etc.

Data
Data consists of raw facts, which the computer can manipulate
and process into information that is useful to people.
Users
People are the computer's operators, or users. The end-
users use programs in managing daily works.

Software
What is Software?
An organized list of computer instructions that tells the
computer how to perform a certain task is called a Software. A
software is often also called a program.
Software is classified into two classes:
◮ System software
◮ Application software

Software
What is System Software?
System Software refers to the operating system and all utility
programs that manage computer resources at a low level,
such as compilers, loaders, linkers, and debuggers.
What is Application Software?
Software programs designed for end-users are called Application
Software. Commonly used application software programs are
word processors, database systems, and spreadsheet programs.

Operating Systems (OS)
What is an Operating System?
A large software program that make the computer-hardware
functional is called Operating System. It provides the
following things.
◮ It provides an interface between the user and the
computer hardware.
◮ It provides a wayfor applications software to communicate
with the hardware.
◮ Itmanagesthesystemresourcessuchasmemoryandalso
allocate CPU time to the task being run.
◮ It manages system security

Facilities of Operating Systems
Operatingsystemprovidesthefollowingfacilitiesfortheusers:
◮ Program creation: it provides editors, debuggers, other
softwaredevelopmenttools.
◮ Program execution: it loads files, performs input/output
(IO) operations.
◮ Access to IO devices: performs read and writes.
◮ Controlled access to files: provides protection
mechanisms, abstraction of underlying device.
◮ System access: controls access to the system, detects
error and response.

Functions of Operating Systems
Operating Systemsprovidethefollowingfunctionality.
◮ UserInterface
◮ Resource Management
◮ Task Management
◮ File Management
◮ Security
◮ Utilities

Functions of Operating Systems: User Interface
User Interface: The User Interfaces allow users to interact
with the computers. It consists of the cursors, prompts,
icons, menus, etc. User Interfaces can be:
◮ CommandDrivenInterface
◮ Menu Driven Interface
◮ GraphicalUserInterface

Command Driven Interface
◮ Withacommand-driveninterface, youtypein aninstruction
which is usually abbreviated, in order to get something done.
◮ Some older operating systems, such as DOS and UNIX, use
command-line interfaces.

Menu Driven Interface
◮This type of user interface produce a list of commands or
options available within a program and the user can make
a selection by using either a mouse or a keyboard.

Graphical User
◮ Most modern operating systems, likeWindowsand the
MacintoshOS,provideagraphicaluserinterface(GUI).
◮ A GUI is based on the desktop metaphor. Graphical objects
appear on a background (the desktop), representing resources
you can use.

Functions of Operating Systems: Resource Management
Resource Management
◮ Processors: Allocationofprocessestoprocessors.
◮ Memory: Allocation of main memory to processes.
◮ IO devices: Access I/O devices, such as keyboard and Mouse.
◮ Files: Space allocation to files and maintenance.

Functions of Operating Systems: Task Management
Task Management
◮ The OS uses interrupt requests (IRQs) to maintain
organized communication with the CPU and other
pieces of hardware.
◮ Eachhardwaredeviceiscontrolledbyapieceofsoftware,
called a driver, which allows the OS to activate and use
the device.
◮ Theoperatingsystemprovidesthesoftwarenecessaryto
link computers and form a network.

Functions of Operating Systems: File Management
File Management
◮ The operating system keeps track of all the files on each disk.
◮ Users can make file management easier by creating a
hierarchical file system that includes folders and sub-
folders arrangedinalogicalorder.

Functions of Operating Systems: Security
Security
◮ Protection of the systems and user resources from
intentional as well as careless misuse.
◮ Security deals usually with threats from outside of the
system that affects the integrity and availability of the
system.
◮ Applying security mechanisms to protect systems and
data, such as asking log-in credentials to access system,
applying encryption to protect information, etc.

Functions of Operating Systems: Utilities
Utilities
◮ A utility is a program that performs a task that is not
typically handled by the operating system.
◮ Someutilitiesenhancetheoperatingsystem’sfunctionality.
◮ Some of the major categories of utilities include:
◮ File defragmentation
◮ Data compression
◮ Backup
◮ Antivirus
◮ Screensavers

Outline
Computer System
Software
Operating System
3 Hardware
4 Computers Today
4
CSE 101: Introduction to Computer

Basic Services
◮ The operating system manages all the other programs
that run on the PC.
◮ Theoperatingsystemprovidesservicestoprogramsand
the user, including file management, memory
management, and printing.
◮ To provide services to programs, the OS makes system
calls requesting other hardware and software resources
to perform tasks.

Sharing Information
◮ Some operating systems, such as Windows, enable
programs to shareinformation.
◮ You can create data in one program and use it again in
other programs without re-creating it.
◮ Windows provides the clipboard, a special area that stores
data cut or copied from one document, so it can be re-used
elsewhere.

Multi-tasking
◮ Multitasking is the capabilityof running multiple processes
simultaneously.
◮ A multitasking OS enables running multiple programs at
the sametime.
◮ There are two types of multitasking: cooperative and
preemptive.

Outline
Computer System
Software
Operating System
3 Hardware
4 Computers Today
4CSE 101: Introduction to Computer Science

What is Application Software?
Application software is the programs that designed for end-
users, such as word processors, database systems, and
spreadsheet programs.
ApplicationSoftwarecanbedividedintwomajorclasses.
◮ General Application Program
◮ Specific Application Program

General Application Program
General purpose application program is a type of software that
can be used for a variety of tasks. For example, word
processors can be used for drafting anything; drafting an
assignment or drafting a book or drafting a business deal.
SomeoftheGeneralApplicationProgramsare,
◮ Software Suite - MS Office
◮ Web Browser - Chrome, Firefox
◮ DesktopPublishing-Pagemaker,Publisher
◮ Database Management System -Oracle,MSAccess

Specific Application Program
Purpose-built customized software programs are called Specific
Application Program. Some of the Specific Application Program are:
◮ Accounting Software of a bank
◮ Sales Management ofa shop
◮ E-commerce of an online-shop
◮ Inventory Control for a warehouse
◮ Pay-roll System of a company
◮ TicketReservationofatransportationcompany

The Parts of Computer System: Hardware
A computer hardware consists of many different parts. They
are divided in two different groups.
◮ Internal Hardware
◮ ExternalHardware

The Parts of Computer System: Hardware
Internal Hardware: An Internal Hardware means hardware
that surrounded by the computer's casing.
External Hardware: By external hardware, we mean all
the computer device that we can see from outside.

Looking inside the machine
A computer hardware devices are categorized as follows:
◮ CPU
◮ Processor
◮ Memory
◮ StorageDevice
◮ (I/O) Device
◮ InputDevice
◮ Output Device

How computers process data?
Computer processes data in a coordinated manner with the
help of hardware and software. Data processing takes place in
the PC's Central Processing Unit (CPU). The system's
memory also plays a crucial role in processing data.
Both the CPU and memory are attached to the system's
motherboard, which connects all the computer's devices
together, enabling them to communicate.

The two main parts of a CPU are the Control Unit and the
Arithmetic Logic Unit (ALU)

How Computer Process Data? - The Control Unit
What is the Control Unit?
ControlUnitcoordinatesallthejobsrunninginacomputer.
Control Unit performs the following things.
◮ The Control Unit is a part of CPU which directs the flow
of data through the CPU,and to and from other devices.
◮ The Control Unit stores the CPU’s instructions for all the
tasks the CPU can perform.

How Computer Process Data? - The Arithmetic Logic Unit
What is Arithmetic Logic Unit?
Arithmetic Logic Unit manipulates data based on the given
operation instructions. ALU can perform the following things.
◮ The actual manipulation of data takes place in the ALU.
◮ The ALU can perform arithmetic and logic operations.
◮ The following operation ALU can perform
Arithmetic Operations Logical Operations
+ addition =; 6= equal to, not equal to
subtraction > greater than
multiplication greater than equal to
division < less than
^ raise by power less than equal to

How Computer Process Data? - Machine Cycle
Machine Cycle
◮ The CPU follows a set of steps, called a machine cycle, for
eachinstructionitcarriesout.
◮ The machine cycle includes two smaller cycles:
◮ Instruction Cycle: theCPU“fetches”acommand ordata
frommemoryand “decodes”itforthe processing.
◮ Execution Cycle: the CPU carries out the instruction, and may
storethe instruction’sresultinmemory.

Looking inside the machine: Memory
Memory
◮ The smallest usable unit of measure for memory is the byte.
◮ Computersworkwith largerchunks of data, measured in
multiple bytes, as shown below:
◮ 1 byte = 8 bits
◮ 1 kilobyte (KB) = 210 bytes = 1,024 bytes
◮ 1 megabyte (MB) = 220
bytes = 1,048,576 bytes
◮ 1 gigabyte (GB) = 230
bytes = 1,073,741,824 bytes
◮ 1terabyte(TB) = 240 bytes=1,099,511,627,776 bytes
◮ 1 petabyte (PB) = 250 bytes = 1,125,899,906,842,624 bytes
◮ 1 exabyte (EB) = 260 bytes = 1,152,921,504,606,846,976
bytes
Muhammad

Computers Today
Today’s computers can be classified as follows.
◮ Supercomputers
◮ Mainframe Computers
◮ Minicomputers
◮ Workstations
◮ Microcomputers,orPersonal Computers

Computers Today
Computers Today - Supercomputer
Supercomputers are typically one-of-a-kind custom designed
computer having ultra super speed of data processing capability.
The term supercomputer itself is rather fluid, and today's
supercomputer tends to become tomorrow's normal computer

Computers Today - Supercomputer
Common Uses of Super Computer
Researchers, scientists, major universities, military agencies are
the main users of supercomputers. Supercomputers are used for:
◮ Highly complex calculation-Intensive tasks such as
problems involving quantum mechanical physics,
weather forecasting, climate research etc.
◮ Conducting complex simulations, such as detonation of
nuclear weapons, research into nuclear fusion, DNA
sequence matching, cryptanalysis etc.

Computers Today - Mainframe Computer
Mainframe computers are computers used primarily by large
organizations for critical applications, bulk data processing
such as census, industry and consumer statistics, enterprise
resource planning, and transaction processing.

Computers Today - Mainframe Computer
The characteristics of Mainframe computers are:
The characteristics of Mainframe computers are:
◮ Mainframe computers can support hundreds or thousands of
users, handling massive amounts of input, output, and storage.
◮ Mainframecomputersareusedinlargeorganizationswhere
many users need access to shared data and programs.
◮ Nearly all mainframes have the ability to run multiple operating
systems and thereby operate not as a single computer but as a
number of virtual machines.

Computers Today - Minicomputer
Minicomputers are smaller than mainframes but larger
than microcomputers.
◮ Minicomputers usually have multiple terminals.
◮ Minicomputers may be used as Network servers and
Internet servers.

Computers Today - Workstations
Workstations are powerful single-user computers.
◮ Workstations are used for tasks that require a great deal
of number-crunching power, such as product design and
computer animation.
◮ Workstations are also often used as network and web
servers.

Computers Today - Microcomputers
Microcomputers are more commonly known as personal computers.
The term PC" is applied to IBM-PCs or compatible computers.
◮ Full-size desktop computers are the most common type of
PC.
◮ Notebook (laptop) computers are used by people who
need the power of a desktop system, but also portability.

Thank You!

Computer system and it class 1

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