# Chapter 3 Uma Gupta Introduction to Information Systems  2000 by Prentice Hall. 3-1 Computer Hardware.

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Chapter 3 Uma Gupta Introduction to Information Systems  2000 by Prentice Hall. 3-1 Computer Hardware

 2000 by Prentice Hall.3-2 Learning Objectives After studying this chapter, you will be able to:  Discuss the fundamentals of data representation  Describe the five hardware components in a computer system and their main functions  Compare and contrast different types of computers according to size and speed: supercomputers, mainframes, minicomputers, workstations, and microcomputers  Explain the process of buying a personal computer

 2000 by Prentice Hall.3-3 Size and Time Units for Computers Amount of Memory Unit Byte Kilobyte (kB) Megabyte (MB) Gigabyte (GB) Terrabyte 8 bits 1,000 (10 3 ) bytes* 1,000,000 (10 6 ) bytes 1,000,000,000 (10 9 ) bytes 1,000,000,000,000 (10 12 ) bytes * This number is an approximation. The exact value is 1,024 bytes.

 2000 by Prentice Hall.3-4 The Five Computer Components The central processor Secondary storage Input devices Output devices Communication devices

 2000 by Prentice Hall.3-5 The Central Processor  The central processor consists of two parts  The central processing unit (CPU) –Arithmetic-log unit (ALU) –The control unit  Primary storage –Random access memory (RAM) –Read-only memory (ROM) –Cache memory

 2000 by Prentice Hall.3-6 Secondary Storage  There are two main types of secondary storage  Sequential –Magnetic tape  Direct access –Magnetic disks –Redundant array of independent disks (RAID) –CD-ROM –Digital Versatile Disk (DVD)

 2000 by Prentice Hall.3-7 Input Devices  Input devices are the devices through which a computer accepts data  Touch screens  Voice-recognition systems  Optical character reader (OCR)

 2000 by Prentice Hall.3-8 Output Devices  An output device is any device that helps the user to view the output of the computer  Computer screen (video display terminal)  Printers

 2000 by Prentice Hall.3-9 Features of the Three Types of Printers Features Type of Printer Dot MatrixCheapest type of printer. Uses pins to press on a ribbon to make characters. Noisiest type of printer. Higher-quality output than the dot matrix. Uses a nozzle to spray ink onto a page. Produces about 2 to 8 ppm. Can print documents in color. Quieter than a dot matrix printer, but more expensive to operate. Highest-quality output, comparable to magazine output. Quietest printer. Typically the most expensive printer. Produces 4 to 16 ppm or more. Inkjet Laser

 2000 by Prentice Hall.3-10 Communication Devices  Devices that allow users separated by distance and time to exchange documents, files, graphics, and other digital information.

 2000 by Prentice Hall.3-11 Computers That Support Different Work-group Sizes Personal Information Systems Work-group Systems Enterprise-wide Systems PCs Laptops/Notebooks Hand-held Computers Pen-based Computers Midrange or Minicomputers Workstations Supercomputers Mainframes

 2000 by Prentice Hall.3-12 Supercomputers  Some of the fastest and largest computers available today are supercomputers  Supercomputers have two common characteristics  The ability to process instructions in parallel (parallel processing)  The ability to automatically recover from failures (fault tolerance)

 2000 by Prentice Hall.3-13 Mainframes  Mainframes are frequently enterprise-wide systems and are ideal for transaction processing, financial applications, payroll, investment analysis, and other applications that require extensive computations  Many users can simultaneously use the mainframe  One large disadvantage of the mainframe is that it is expensive to purchase, operate, and maintain

 2000 by Prentice Hall.3-14 Midrange,or Minicomputers, and Workstations  Although midrange computers are slower and often have less memory than mainframes, they are workhorses that can deliver excellent “bang for the buck”  Workstations lie somewhere between midrange and personal computers  They can be used by individuals or groups  They are faster and more sophisticated than PCs  They include numerous productivity tools that increase efficiency

 2000 by Prentice Hall.3-15 Network Computers  The network computer, also known as “thin clients” is a simplified version of a personal computer  They are used mainly to access programs that reside on a company’s network or on the Internet  Network computers are well suited for task-oriented jobs, such as data entry, order entry, and assembly line work  Network computers function by downloading all applications from a central computer and obtaining and storing all data back on the central computer  Network computers can offer cost efficiencies, but they rely heavily on network traffic and can cause bottlenecks

 2000 by Prentice Hall.3-16 Microcomputers or Personal Computers (PCs)  The memory size and processing capabilities of microcomputers are less than mainframes and midrange computers  However, hardware technology advances have made the PC a compact and powerful machine  A PC can be configured to meet the specific needs of users

 2000 by Prentice Hall.3-17 Mobile Computers: Laptops, Notebooks, Handheld, and Pen-based  These computers are battery operated so they can be used anytime, anywhere  The portability of notebook and handheld computers has increased the productivity of many employees

 2000 by Prentice Hall.3-18 A Comparison of Types of Mobile Computers Description Type LaptopFits on a user’s lap and is slightly larger than a notebook. Has full PC functionality with a reduced keypad and screen. Has a floppy drive. Has full PC functionality with a reduced keypad and screen and no floppy drive. Smaller than a laptop or notebook computer. Has a built-in monitor that can be operated from the palm of one’s hand so the keyboard and screen are smaller than a laptop. Often, the keyboard requires an electronic pen to input data. Uses an electronic writing pad and a light-sensitive electronic pen to input data. Can download text, photos, and other applications from PCs and transmit data via infrared rays; users input information on the LCD watch face that turns into a small keyboard. Notebook Handheld Pen-based Wrist

 2000 by Prentice Hall.3-19 Six Technical Considerations in Buying a PC Monitors RAM Secondary Storage Clock Speed Processor Expansion Slots

 2000 by Prentice Hall.3-20 Business Guidelines for Hardware Success  Cost Is Only Part of the Story  Many benefits resulting from information systems are intangible and tough to measure –increased productivity –improved decision making –faster customer service  Don’t Compromise on Capacity and Reliability  The motto “If it ain’t broke, don’t fix it” does not apply to hardware capacity and reliability

 2000 by Prentice Hall.3-21 Business Guidelines for Hardware Success (cont.)  Infrastructure, Infrastructure, Infrastructure  Machines no longer work in isolation  All business decisions should consider the technology infrastructure and IS professionals should be prepared to sell its importance to top management  Support Is Crucial  When there is a problem, users expect the problem to be fixed almost immediately  Who will provide support? What is the nature of support? When will the support be provided?

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