Computer System Organization

Presentation made by: Ms. Archika Bhatia COMPUTER SYSTEM ORGANISATION

Index Evolution of computers History of computing Basics of computer and its operation: Functional Components and their interconnections Classification of Computers Software Concepts: Types of Software - System Software, Utility Software and Application Software;

EVOLUTION OF COMPUTER The development of the modern day computer was the result of advances in technologies and man's need to quantify. Let us look at some of the important milestones in the evolution of computers .

ABACUS The abacus was invented in 3000 BC in Babylonia. Beads on rods to count and calculate still widely used in Asia!

Slide Rule Slide Rule 1630 based on Napier’s rules for logarithms used until 1970s

PASCAL’S ADDING MACHINE In 1642 AD, Blaise Pascal , a French mathematician invented a calculating machine named as Adding Machine . This machine was capable of doing Addition and Subtraction. This device is known as the First Calculator of the world .

LEIBNITZ’S CALCULATOR In 1671 AD, Gotfried Leibnitz, a German Mathematician improved the Adding machine and made a new machine capable of performing multiplication and division also.

first stored program - metal cards first computer manufacturing still in use today! Jacquard Loom - 1801

BABBAGE’S DIFFERENCE ENGINE Charles Babbage was a British mathematician. In 1822, he designed a machine called Difference Engine . It aimed at calculating mathematical tables. Since the technology was not so advanced at that time this machine could not be made.

BABBAGE’S ANALYTICAL ENGINE In 1833, Charles Babbage designed a machine called Analytical Engine . It had almost all the parts of a modern computer. Unfortunately, this machine could not be built because of lack of technology. His designs remained a concept. His great designs earned him the title of ‘ FATHER OF COMPUTERS‘.

LADY ADA Lord Byron's daughter, Ada, Countess of Lovelace , suggested to Babbage that he use the binary system in his machine. She wrote programs for his analytical engine in 1840, becoming the world's first computer programmer.

HOLLERITH’S TABULATING MACHINE Hollerith, a Mathematician, invented a fast counting machine named Tabulating Machine in 1880. This machine was used by American Department of Census to complete their 1880 census data.

MARK I COMPUTER Howard Aiken of Harvard University in USA joined hands with the company IBM. He developed a computer named Mark I in 1943. It could perform mathematical operations very fast. It could perform one operation per second.

ENIAC The first electronic computer ENIAC was developed in 1946 by a team lead by Professor Eckert and Mauchly at the University of Pennsylvania in USA. Electronic Numerical Integrator and Computer (ENIAC) was very huge and very fast. It could solve 5000 operations per second.

INTEL 8080 PROCESSOR In 1974 the Intel 8080 processor was introduced - it became the basis for the first personal computers.

Definition of Computer Electronic Device Accepts and stores input Manipulates result Outputs results Under direction of stores programs and instructions

Characteristics of Computer Speed Accuracy Diligence : not afflicted to tiredness, monotony, lack of concentration like human beings. Reliability Versatility : can work with different types of data like sound, graphics, audio. Memory

What is Data and Information Data is raw facts ex: India, 200, 4, Cricket, Wicket Information is meaningful and arranged form of data ex: India’s score in Cricket is 200 for 4 wickets.

Hardware refers to physical components that can be seen and touched. E.g. CPU, Memory, I/O devices. HARDWARE SOFTWARE Software is a set of programs that make the Hardware of the computer run. Program is a set of instructions.

FIRMWARE LIVEWARE Firmware is like prewritten program that is permanently stored in read-only memory. BIOS ( Basic Input Output Services ) instructions are an example of firmware. It is the term generally used for the people associated with and benefited from the computer system.

Classification of Computer Systems On the basis of Technology Generations of computers On the basis of Purpose General Purpose, special Purpose computers On The basis of size & Speed Micro, Mini & Super Computers On the basis of how it functions Analog, Digital & Hybrid Computers

Generations of Computer Each generation of computer is characterized by a major technological development that fundamentally changed the way computers operate, resulting in increasingly Technology Based Classification of Computer Systems smaller, cheaper, more powerful more efficient and reliable devices.

TIME PERIOD : 1940's-1950's TECHNOLOGY USED : Vacuum Tubes SIZE AND SPEED : Huge, taking up entire rooms, Slow speed LANGUAGE USED : Machine language COST : System and working cost very high. OTHER FEATURES : Used a great deal of electricity. Generated a lot of heat. Input was based on punched cards and paper tape, and output was displayed on printouts. EXAMPLE : UNIVAC and ENIAC Structure of a Vaccum Tube UNIVAC ENIAC FIRST GENERATION

SECOND GENERATION TIME PERIOD : 1950's- 1960's TECHNOLOGY USED : Transistors SIZE AND SPEED : Lesser size and increased speed LANGUAGE USED : Assembly language and languages like COBOL and FORTRAN COST : Cost decreased OTHER FEATURES : More efficient and reliable. Though the transistors still generated a great deal of heat that subjected the computer to damage, it was a vast improvement over the vacuum tube. Second-generation computers still relied on punched cards for input and printouts for output. EXAMPLE : UNIVAC 1108, IBM 1401, CDC 1604 UNIVAC 1108 IBM 1401 TRANSISITORS

THIRD GENERATION TIME PERIOD : late 1960's-1970's TECHNOLOGY USED : Integrated Circuit SIZE AND SPEED : Size Lesser and speed further increased LANGUAGE USED : Operating System was developed. COST : Cost decreased further OTHER FEATURES : Instead of punched cards and printouts, users interacted with third generation computers through keyboards and monitors and interfaced with an operating system , which allowed the device to run many different applications at one time with a central program that monitored the memory. Computers for the first time became accessible to a mass audience because they were smaller and cheaper than their predecessors. EXAMPLE : IBM-360 series, Honeywell Model 316, Honeywell – 6000 series, CDC – 1700. IBM 360/50

FOURTH GENERATION TIME PERIOD : 1970's-today TECHNOLOGY USED : Microprocessor SIZE AND SPEED : Reduced size and tremendous speed LANGUAGE USED : High Level Languages like PASCAL, COBOL, C, C++, JAVA COST : Reduced Cost OTHER FEATURES : Microprocessors also moved out of the realm of desktop computers and into many areas of life as more and more everyday products began to use microprocessors. As these small computers became more powerful, they could be linked together to form networks, which eventually led to the development of the Internet. Fourth generation computers also saw the development of GUIs, the mouse and handheld devices. EXAMPLE : Intel 4004, Apple Macintosh The Macintosh 128K , the first Macintosh, was the first commercially successful personal computer to use images, rather than text, to communicate. Intel 4004D microprocessor

FIFTH GENERATION TIME PERIOD : 1990's -today TECHNOLOGY USED : Microprocessor SIZE AND SPEED : Reduced size and tremendous speed LANGUAGE USED : Based on Artificial intelligence COST : Reduced Cost OTHER FEATURES : Fifth generation computing devices, based on artificial intelligence, are still in development, though there are some applications, such as voice recognition, that are being used today. The goal of fifth-generation computing is to develop devices that respond to natural language input and are capable of learning and self-organization. EXAMPLE : Parallel Inference Machine Note Artificial Intelligence is the branch of computer science concerned with making computers behave like humans. Voice Recognition is the field of computer science that deals with designing computer systems that can recognize spoken words.

The current classifications of computers place them into four categories: Super Computers, Mainframes, Minicomputers, Microcomputers (Personal Computers) Size and Speed Based Classification of Computer Systems

SUPER COMPUTER The fastest type of computer. Supercomputers are very expensive and are employed for specialized applications that require immense amounts of mathematical calculations. For example, weather forecasting requires a supercomputer. Other uses of supercomputers include animated graphics, , nuclear energy research, and petroleum exploration. Characteristics Powerful Expensive Dedicated to one purpose - weather, satellites, military Used by large governments or very large companies Can be used by thousands of people at the same time Very large - fill rooms

Sixteen racks of IBM's Blue Gene/L supercomputer can perform 70.7 trillion calculations per second, making it the fastest machine known so far.

MAINFRAME In the early days of computing, mainframes were huge computers that could fill an entire room or even a whole floor. As the size of computers has decreased while the power has increased, the term mainframe has fallen out of use in favor of enterprise server. You'll still hear the term used, particularly in large companies to describe the huge machines processing millions of transactions every day. Characteristics: Expensive Powerful and fast Is not limited to one job Used by business and small government organizations The main difference between a supercomputer and a mainframe is that a supercomputer channels all its power into executing a few programs as fast as possible, whereas a mainframe uses its power to execute many programs simultaneously.

MINICOMPUTER Another term rarely used anymore, minicomputers fall in between microcomputers (PCs) and mainframes (enterprise servers). Minicomputers are normally referred to as mid-range servers now. Characteristics: Smaller than mainframe Can do several jobs at once Can be used by many people at one time Used by small companies

PERSONAL COMPUTER The term microcomputer, also known as personal computer (PC), or a computer that depends on a microprocessor. A microcomputer contains a central processing unit (CPU) on a microchip (the microprocessor), a memory system (read-only memory and random access memory), placed on a motherboard. Example: desktop, notebook, laptop, handheld devices. Charcteristics: developed in 1980 designed for single user not very powerful or expensive found in homes

The current classifications of computers place them into four categories: Analog Computer Digital Computer Hybrid Computers Classification of Computers of On the basis of How It Functions

Operate on continuous data, like measuring temp. changes Faster Accuracy of an analog computer is restricted to the accuracy with which physical quantities can be sensed and displayed. Specific Purpose computers Digital Computers Analog Computers Classification of Computers of On the basis of How It Functions Digital computers work on discrete data. digital computer can process data with greater accuracy We generally use digital computers for business and scientific data processing. Digital Computers

Hybrid computers are computers that comprise features of analog computers and digital computers . The digital component normally serves as the controller and provides logical operations , while the analog component normally serves as a solver of differential equations . Hybrid Computers

General Purpose Computers Special Purpose Computers Purpose Based Classification of Computer Systems The First Real Computers: 1939: Konrad Zuse completed the first programmable, general-purpose digital computer Special-purpose computer: Dedicated computers that perform specific tasks Controlling the temperature and humidity Monitoring your heart rate Monitoring your house security system

Types of Software Software ( Set of programs that govern the operations of computer ) System Software ( Software that controls internal computer operations ) Application Software ( Set of programs to carry out operations for a specified application ) Operating System ( Software which acts as an interface between user and the hardware ) Language Processor ( Software which converts HLL progran into machine language ) Packages ( General utility software ) Utilities ( perform house keeping ) Customized Software ( Tailor made software according to user’s needs )

UTILITY SOFTWARE Anti Virus e.g., Norton, File Management tools Compression tools Disk Management tools ( Disk Cleanup, Disk Fragmentor, Backup)

APPLICATION SOFTWARE Word Processor Presentation tools Spreadsheet Package Database Management System Business Software ( ex: School Management System, Inventory Management System, Payroll System, Financial Accounting, Hotel Management, Reservation System)

Language Processors Assembler: This language processor converts the program written in Assembly language into machine language. Compiler: This converts HLL program into machine language in one go . After the compiler is not needed. It is removed from the memory.Therefore, better memory utilization . Interpreter: This converts HLL program into machine language by converting and executing it line by line . It must be present In memory every time program is executed. Therefore, unnecessary usage of memory . There are three types of Language Processors:

Generations of Computer Languages Low Level Language Fifth Generation Fourth Generation Third Generation (High Level Language) Second Generation (Assembly Language) First Generation (Machine Language)

Need For Operating System To make computer system convenient to use To use computer hardware in an efficient manner It decides How to do? What to do? When to do?

Functions of Operating System Processor Management Keep track of processor Decide which job should use the processor Allocate Processor Deallocate Processor File Management Keep track of files Decide which job should use the file and for what purpose Allocate the file for use Deallocate file after use

Functions of Operating System Device Management Keep track of devices Decide which job should use the processor Allocate Processor Deallocate Processor Memory Management Keep track of processor Decide which job should use the processor Allocate Processor Deallocate Processor

Types of Operating System Interactive (GUI) Time Sharing Real Time Distributed

FIRST GENERATION : Machine language i.e. language of 0 and 1 SECOND GENERATION : Assembly language Similar to English Uses mnemonics codes THIRD GENERATION : High Level Language Very close to English E.g. C, C++, Java, VB FOURTH GENERATION : Languages for accessing databases FIFTH GENERATION : Uses a visual or graphical development interface to create source language that is usually compiled with a 3GL or 4GL language compiler Used mainly in artificial intelligence research E.g. Prolog , OPS5 , and Mercury

B ASIC C OMPONENTS of C OMPUTER S YSTEMS Secondary Memory (Block Diagram)

Input/Output B ASIC C OMPONENTS of C OMPUTER S YSTEMS Secondary Memory

INPUT UNIT Accepts data from outside world. Converts data into binary form acceptable to the machine. Send data in binary form to computer for further processing.

INPUT DEVICES SCANNER LIGHT PEN

Terminal Simpler than a PC Designed strictly for input and output Has keyboard and screen Does not have a processor Connected to computer with telecommunication line Allows user to key data directly into computer Input/Output Page 28 B ASIC C OMPONENTS of C OMPUTER S YSTEMS

Common input methods: Magnetic ink character recognition (MICR) – used to process bank checks Optical character recognition (OCR) – directly scans typed, printed, or handwritten material Imaging – inputs digital form of documents and photos Bar code labeling – scans bar codes on packages or products, and reads into computer Input/Output Page 29 B ASIC C OMPONENTS of C OMPUTER S YSTEMS

Common output methods: Print – output to paper using various types of printers Computer output microfilm (COM) – microfilm generated for archive copies in small space Voice response units – computer recognizes input, generates verbal response messages Input/Output Page 29 B ASIC C OMPONENTS of C OMPUTER S YSTEMS

Input/Output Page 29 Multimedia – relatively new term for computer input and output in the form of text, graphics, sound, still images, animations, and/or video Of interest … B ASIC C OMPONENTS of C OMPUTER S YSTEMS

Computer Memory B ASIC C OMPONENTS of C OMPUTER S YSTEMS Secondary Memory

Memory All data flows to and from memory Divided into cells : Each has a unique address Memory cell types: Byte – stores one character of data Word – stores two or more characters of data Computer Memory Page 31 B ASIC C OMPONENTS of C OMPUTER S YSTEMS

Each memory cell is a set of circuits Each circuit is on or off (represented by 1 or 0) Each circuit corresponds to a bit (binary digit) Most computers – 8 bits (circuits) represents a character ( byte ) 2 common bit coding schemes used today: ASCII EBCDIC Bits and Coding Schemes Page 32 B ASIC C OMPONENTS of C OMPUTER S YSTEMS

Bits and Coding Schemes Page 32 Figure 2.4 Computer Coding Schemes . . . . . . . . . . . . . . . . . .

Arithmetic/Logical Unit B ASIC C OMPONENTS of C OMPUTER S YSTEMS Secondary Memory

Consists of VLSI circuits on a silicon chip Carries out: arithmetic – add, subtract, multiply, divide … logical operations – comparing two numbers Arithmetic/Logical Unit Page 33 B ASIC C OMPONENTS of C OMPUTER S YSTEMS

Computer Files (Secondary Memory) B ASIC C OMPONENTS of C OMPUTER S YSTEMS Secondary Memory

B ASIC C OMPONENTS OF C OMPUTER S YSTEMS When power is off, everything stored in Main memory is lost Computer files are used to store data for long term File storage devices (Secondary Memory) : Magnetic tape drives, disk drives, floppy drives Optical CD or DVD drives Computer Files (Secondary Memory) Page 33

Types of DASD Fixed (hard) drives BASIC COMPONENTS OF COMPUTER SYSTEMS Computer Files Page 34 Figure 2.7 Diagram of a Magnetic Disk Drive

Types of DASD Removable: Floppy drives Zip drives Newest: portable DASD for PCs – keychain drive BASIC COMPONENTS OF COMPUTER SYSTEMS Computer Files (Secondary Memory)

Computer System Organization

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