SSD2: Introduction to Computer Systems ISS,WHU

Unit 1. Computer Systems 1.1 Overview of Computer Systems 1.2 Evolution of Computer Systems 1.3 Data Representation in a Computer System

Subsystems of a Computer Subsystems of a Computer Software System Operating System (Unix, Mac OS, Microsoft Windows) Web browser (Netscape, Internet Explorer) Office productivity applications (Microsoft Office, Star Office) Hardware System Keyboard Monitor System unit Network System Internet services ( ) Network connections (modems, network cards) Internet

Hardware System Speakers Printer Mouse Keyboard Monitor System unit

Hardware Components: Peripheral Devices Equipment added to computer to enhance its functionality Modify and expand the basic computer system Examples of peripheral devices: –Keyboard –Monitor –Mouse –Printer –Scanner –Digital Video Camera –Graphic Tablet –Joy Stick

Hardware Components: Storage Devices Optical Disks –CD-ROM –CD-RW –DVD-ROM Magnetic Disks –Floppy disk –Hard disk (removable & fixed)

What is Software? Software is a set of computer instructions or data. Software receives input from the user and processes this input through the computer to produce output. Software directs how the computer interacts with the user. Software specifies how to process the user's data

Software System Two categories: –Operating system software, –Application software Hardware System Application Software Operating System Software Users

Software System Operating system software, also called system software, is the master controller for all activities that take place within a computer –Examples of OS software: Microsoft Windows Unix Mac OS Application software is a set of one or more computer programs that helps a person carry out a task –Examples of application software: Microsoft Word Internet Explorer Macromedia Dreamweaver Adobe Acrobat Reader

Network System A network provides connections among computers to enable computers on a network to share data (e.g. documents), hardware (e.g. printers), and software resources (e.g. application programs). Network users can also send messages to each other. A network must be secured to protect data from unauthorized usage (e.g. using login name and password to gain access to a network). Network connection components: Network Interface Card (NIC) Modem Phone line or cable Internet Service Provider (ISP) Internet

Basic Computer Model All computers perform four basic operations –Input Data –Process Data –Store Data –Output Data

Basic Operations Input data is to feed information which can be supplied by any person, environment or other computer. Processing data is manipulating data by performing calculations, sorting lists of words or numbers, drawing pictures. Storing data is for future retrieval and processing. Memory holds data that is waiting to be processed, and storage areas hold data permanently until the data is deleted. Output data is the result produced by a computer, which includes reports, documents, music, graphs and pictures.

Categories of Computers Computers are classified based on their technology, function, physical size, performance and cost. The categories of computers include: –Personal computers –Handheld computers –Mainframes –Supercomputers

Personal Computer (PC) Designed to meet the computing needs of an individual –Desktop computers –Notebook computers

Handheld Computer Designed to fit into a pocket, run on batteries, and be used while you are holding it Also called a PDA (Personal Digital Assistant) –Send and receive –Use maps and global positioning –Maintain expense account, contacts, to-do lists, memos, etc. –Make voice calls using cellular service A personal digital assistant (PDA) accepts info on a touch-sensitive screen

Mainframe Computer It is a large and expensive computer that is capable of handling requests and passing data simultaneously to many users. Used by governments and large corporations to provide centralized storage and control Processes billions of data per second and includes many units where one directs overall operations, a second one handles communication between users, and third searches for requests given by user.

Supercomputer It is the fastest type of computer. Supercomputers are very expensive and are employed for specialized applications that require immense amounts of mathematical calculations. It is often used for: –Breaking codes –Modeling weather systems –Simulating nuclear explosions –Research simulations Capable of performing over 600 billion floating-point operations per second. Examples: Deep Blue, PARAM 1000, Hitachi's SR2201

Evolution of Computers Needed calculation devices to keep track of accounting for commerce 1200sManual Calculating Devices: the abacus

Evolution of Computers (continued) 1600sMechanical Calculators –Used wheels, gears, and counters –To work a mechanical calculator, the operator enters the numbers for a calculation, and then pulls a lever or turns a wheel to carry out the calculation –Example: the Pascaline invented by Blaise Pascal. It used some principles of the abacus, but used wheels to move counters.

Evolution of Computers (continued) 1800sPunched Cards punched card 1800sPunched Cards punched card –Used holes following a specific pattern to represent the instructions given to the machine or stored data –Different program instructions can be stored on separate punched cards, which can be fed through the computing machine repeatedly. –Once punched, the cards were fed into a card reader that used an array of metal rods to electronically read the data from the cards and tabulate the results. This is called the Hollerith Tabulating Machine –Hollerith incorporated The Tabulating Machine better known today as IBM.

Evolution of Computers (continued) Charles Babbage designed a new general- purpose calculating device, the Analytical Engine, which is the ancestor of modern computers. –It included the essential components of present-day computers, which are input, process, storage, and output of data.

Evolution of Computers (continued) 1940sVacuum Tubes –Used to control the flow of electrons. Since vacuum tubes responded faster than mechanical components, faster computations were possible. But, the tubes consumed a lot of power and burned out quickly. –The first computer prototype using vacuum tubes was ENIAC (Electronic Numerical Integrator and Computer). It was designed to calculate trajectory tables for the U.S. Army during World War II, but it was not completed until three months after the war.

Evolution of Computers (continued) 1950sTransistors –Smaller, cheaper, more reliable, and consumed less power than vacuum tubes. –Could perform 200,000 to 250,000 calculations per second.

Evolution of Computers (continued) 1960sIntegrated Circuits –Thin slice of silicon packed with microscopic circuit elements such as wire, transistors, capacitors, and resistors. –Enabled the equivalent of thousands of vacuum tubes or transistors to be packed onto a single miniature chip about the size of your fingernail –Reduces the physical size, weight, and power requirements for devices such as computers

Evolution of Computers (continued) 1970s to PresentMicroprocessor –Combined components of a computer on a microchip –Can be manufactured and then programmed for various purposes

Evolution of Computers (continued) Pace of Processor Advancement

Applications of Computer Systems In Education –Multimedia-Facilitated Learning –Simulation-Based Education –Intelligent Machine-Based Training –Interactive Learning In Business –Supply Chain Management –Project Management –Customer Relationship Management –Sales and Marketing Using Electronic Commerce –Manufacturing Research

Applications of Computer Systems In Entertainment –Movies –Video Games –Music –Digital Photography –Travel –Wearable Computer Systems Developing new applications of computer systems: –Research at Carnegie Mellon University –Research at Massachusetts Institute of Technology Media Lab

Computer Industry Computer industry encompasses those companies that manufacture handheld computers, personal computers, high- end workstations, servers, mainframes, and supercomputers Information technology industry (or IT industry), is typically used to refer to the companies that develop, produce, sell, or support computers, software, and computer-related products IT companies include: –Equipment manufacturers –Chipmakers –Software publishers –Service companies –Retailers

Computer Industry (continued) The 1990s spawned a group of Internet- based companies that came to be called dot coms, from the companies domain names, which inevitably ended with.com and many of the companies even incorporated.com into their official company names Amazon.com was one of the first Internet- based companies

Computer Industry (continued) Governments and private businesses have discovered that they can become much more efficient with a liberal application of computers and other information technologies As businesses globalize, they encounter new competitors with technological advantages Bottom line: if your business competitors turn to technology, so must you

Careers in Computing A systems analyst investigates the requirements of a business or organization, its employees, and its customers in order to plan and implement new or improved computer services A security specialist analyzes a computer systems vulnerability to threats from viruses, worms, unauthorized access, and physical damage A computer programmer designs, codes, and tests computer programs A quality assurance specialist participates in alpha and beta test cycles of software A database administrator analyzes a companys data to determine the most effective way to collect and store it

Careers in Computing (continued) A network specialist/administrator plans, installs, and maintains one or more local area networks A computer operator typically works with minicomputers, mainframes, and supercomputers A computer engineer designs and tests new hardware products, such as computer chips, circuit boards, computers, and peripheral devices A technical support specialist provides phone or online help to customers of computer companies and software publishers

Careers in Computing (continued) A technical writer creates documentation for large programming projects, and writes the online or printed user manuals that accompany computers, peripheral devices, and software A computer salesperson, or sales rep, sells computers A Web site designer creates, tests, posts, and modifies Web pages A manufacturing technician participates in the fabrication of computer chips, circuit boards, system units, or peripheral devices

Careers in Computing (continued) The U.S. Bureau of Labor Statistics (BLS) projects that the number of jobs in the computer industry will substantially increase between now and 2008 According to the BLS, the largest increases in available jobs will be for database administrators, computer support specialists, and computer engineers Over the next few years, economic trends may cause significant changes in the job market A daily look at in-demand tech skills can be viewed at:

IT Salaries in the U.S. Source:

1.3 Data Representation in a Computer System Bits and Bytes Number Systems

1.3.1 Bits and Bytes Recall computers are made up of electrical components Data can be represented electronically with electrical components being on or off. On and off states can be represented using digits 0s and 1s. For example: –0: Off state –1: On state Thus, data can be represented digitally using digits 0 and 1. 0 and 1 are called binary digits. Each binary digit is called a bit. Eight Bitsequal to one byte.

Data Representation Using Binary Digits A piece of data, such as an alphabet letter, may be represented using a sequence of binary digits- 0's and 1's. There are several types of codes used to represent character data. Extended ASCII (America Standard Code for Information Interchange) code, the alphabet letter "a" can be represented using a series of eight binary digits, " "

Extended ASCII code uses eight bits (or one byte) to represent input characters.

data representing All data, including audio, visual, and program instruction data can be represented and stored using a sequence of binary digits, or a sequence of bytes.

A file is a collection of data. In some files, the bits of data directly encode individual letters, numbers, and punctuation symbols that make up words and sentences. In other files such as an image file, the bits of data need to be computed in order for them to transform to images that we can interpret.

A file is a collection of data. Most applications encode information in specialized ways that are not readable by humans. such as Microsoft Word or PowerPoint even though Microsoft Word is often used to edit text, a Word document cannot be properly displayed by a simple text editor like Notepad because the document includes information in a format specific to Microsoft Word. Therefore, it must be opened by Microsoft Word to be read. Some files have a header section that indicates which format was used to encode the data in order to allow the computer to reassemble the binary data back into the human-readable form of the document.

Increasing Need for Bytes Decade1970s1980s1990s2000s Order of magnitude in Storage capacity ThousandsMillionsBillionsTrillions PrefixKilo (10 3 ) Mega (10 6 ) Giga (10 9 ) Tera (10 12 ) AbbreviationKMGT

In terms of storage, more is betterwhich more information in the form of both data and programs that act on that data can be stored. Corresponding to the growth in storage capacity, memory capacity is also increasing. Moreover, memory technologies are getting smaller, lighter, and faster, for about the same price.

1.3.2 Number Systems Decimal: base 10 (digits 0-9) Binary: base 2 (digits 0-1) Hexadecimal: base16 (digits 0-9 and A-F) –Each hexadecimal digit represents four binary places. –Hex digit can be used as shorthand for binary notation One Hex digit four bits One byte = 8 bits two Hex digits