chapter 3 uma gupta introduction to information systems 2000 by prentice hall. 3-1 computer...
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2000 by Prentice Hall. 3-1
Chapter 3
Uma GuptaIntroduction to Information Systems
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 MemoryUnit
Byte
Kilobyte (kB)
Megabyte (MB)
Gigabyte (GB)
Terrabyte
8 bits
1,000 (103) bytes*
1,000,000 (106) bytes
1,000,000,000 (109) bytes
1,000,000,000,000 (1012) 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
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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)
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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
FeaturesType of Printer
Dot Matrix Cheapest 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 InformationSystems
Work-group SystemsEnterprise-wide Systems
• PCs• Laptops/Notebooks• Hand-held Computers• Pen-based Computers
• Midrange orMinicomputers
• 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
DescriptionType
Laptop Fits 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
SecondaryStorage
ClockSpeed
Processor
ExpansionSlots
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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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