1. 11
Computer Hardware

2. Chapter Objectives
Identify the major types, trends, and uses of microcomputer, midrange, and mainframe computer systems.
Outline the major technologies and uses of computer peripherals for input, output, and storage.
Identify and give examples of the components and functions of a computer system.
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3. Chapter Objectives
Identify the computer systems and peripherals you would acquire or recommend for a business of your choice, and explain the reasons for your selections
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4. Trends in Computer System Capabilities
First
Generation
Second
Third
Fourth
Fifth
Vacuum
Tubes
Solid-State
Integrated
Circuits
LSI, VLSI
Micro-
processors
Greater
Power,
Smaller
Footprint
Trend: Toward Smaller, Faster, More Reliable, and Less Costly
Trend: Toward Easy to Purchase, and Easy to Maintain
What is a computer system? A computer system is an interrelated combination of components performing specialized functions to provide end users with a powerful information-processing tool.
Computers have radically changed from their early beginnings. As the figure indicates, the…
First Generation. First generation computers ( ) used hundreds or thousands of vacuum tubes for their processing and memory circuitry. These were room size computers that generated a great deal of heat requiring large air conditioning and maintenance support.
Second Generation. Second generation computers ( ) used transistors and other solid-state semiconductor devices wired to circuit boards. Magnetic cores were used for memory and removable magnetic disk packs and magnetic tape were used for secondary storage.
Third Generation. Third generation computers ( ) began using integrated circuits consisting of thousands of transistors and other circuit elements etched on tiny chips of silicon allowing for increased memory and processing speeds of several millions of instructions per second (MIPS).
Fourth Generation. Fourth generation computers (1979-present) use large scale integration (LSI) and very large scale integration (VLSI) that cram hundreds of thousands or millions of transistors and other circuit elements on each chip.
Fifth Generation. The next generation of computers should continue the trend toward more power, more speed, smaller size, and longer terms of service. Fifth generation computers may use superconductor circuits or other developing technologies to process and store information
Teaching Tips
This slide corresponds to Figure 3.3 on pp.95 and relates to the material on pp
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5. Computer System Categories
Mainframe
Computers
Midrange
Microcomputers
Traditional categories of computer systems are rapidly diminishing as new technologies begin to merge the major characteristics of computer systems. However, within these parameters, the following are generally true:
Microcomputers. These are the smallest computer systems, ranging in size from handheld personal digital assistants (PDAs) to laptops to desktop personal computers and workstations. Most microcomputers are designed for single-user application but can be linked via telecommunications to network servers.
Midrange. Midrange or minicomputers are larger and more powerful that most microcomputers but smaller and less powerful than most large mainframes. Midrange systems are often used in business and scientific research. They are especially well suited for specialized tasks, usually so as to dedicate computing power to a specific function (such as backroom order processing) without having to share time on an organization's larger mainframe. Of course, many small and medium-sized organizations use such computers for their whole operations.
Mainframes. These are large, powerful computers (often filling an entire room) with very large primary storage capacities (from 64 megabytes to several gigabytes of RAM). This feature helps mainframes process information very quickly (at 10 to 200 millions of instructions per second - MIPS).
Lets take a moment to examine these categories of computer systems.
Teaching Tips
This slide corresponds to Figure 3.2 on pp.94 and relates to the material on pp. 94.
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6. Microcomputer Systems
Handheld Computers
PDA, Information Appliances
Notebook Computers
Desktop Computers
Workstations
Microcomputers are the most important category of computer system for business people and consumer. They range in sizes, features, and functions.
Handheld PCs. These range from personal digital assistants (PDAs) to a host of other devices known as information appliances.
PDAs are designed for convenient mobile computing and can use both touch screens, pen-based handwriting recognition, or keyboards to perform such tasks as receiving and sending , accessing the web, creating schedules and list, and communicating with a remote office or web-server.
Information appliances. A PDA is just one example of a larger category of devices known as information appliances. Such devices include a host of smart gadgets—from cellular phones and pagers to web-based game machines and set-top boxes—that can be used to send and receive and access the web.
Notebook computers. Are small portable computers that support mobile workers.
Desktop Computers. Are designed to fit on an office desk and are used to support a wide range of activities for both work and home. They range in speed and size from MHz and all-in-one units, to free standing tower units.
Workstations. Are more powerful desktops that are used to support applications with heavy mathematical computing, and graphical display demands. Consequently they are used to support such applications as computer aided design (CAD), and multimedia application development.
Teaching Tips
This slide relates to the material on pp
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7. Network Computers and Terminals
Network Computer (Thin Client)
NetPC
Network Terminal
Benefits
Lower purchase cost
Easier maintenance
Easier software distribution and licensing
Computer platform standardization
Reduced end user support requirements
Improved manageability
Network computers and terminals are emerging as the serious business-computing platform.
Network Computers. Network computers (NC) are a microcomputer category designed primarily for use with the Internet and corporate Intranets by clerical workers, operational employees, and knowledge workers. NCs are low cost, sealed networked microcomputers with no or minimal disk storage. As a result they depend on Internet and Intranet servers for their operating system and web-browser, Java-enabled application software, and data access and storage.
NC benefits include:
Lower purchase cost
Easier maintenance
Easier software distribution and licensing
Computer platform standardization
Reduced end user support requirements
Improved manageability
Teaching Tip: Ask students what other benefits they believe Networked Computers will provide business. Keep in mind that studies show that the common worker uses their PC for many non-work related activities.
There are two types of Network Computers:
NCs or Thin Clients. These devices generally have no hard disk. They rely on network servers to provide the operating system and application software. They typically use a web browser and can process Java-enabled software.
NetPC. These devices work like a PC with its own software. It may have a hard drive but no floppy drive or CD-ROM. The operating system and applications are managed centrally by network servers.
Still another device becoming more popular is the network terminal, or window terminal.
Network Terminals. Like all terminals, these devices rely on a host processor (server) to perform processing. Hence they have no disk storage.
They typically use multiuser versions of windows 2000, Linux, or unit as the operating system.
Teaching Tips
This slide relates to the material on pp
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8. Client Server Networking
Systems
Servers
Host Systems/
Superservers
Midrange computers have become popular as powerful network servers included in corporate Intranets and Extranets and in client server networks.
A network is a system of microcomputers and servers linked together with telecommunications hardware and software.
Telecommunications. Telecommunications is the use of networks of interconnected computers and peripheral devices to process and exchange data and information. Hardware such as modems allow computers at distant locations to share information over telephone lines. Network operating systems are software programs that control resource sharing and communications flow among computers and peripherals on a local area network (LAN).
Networked computers draw additional computing power from the other computers on the network, which can include other microcomputers, minicomputers, and mainframes. This capability is known as distributed processing.
Distributed Processing. This is the ability to spread the processing requirements for a particular task around the network to take advantage of unused processing capacity.
Client server architectures, which are used frequently in businesses have the following components:
Client. A client on a network is typically a microcomputer that serves an end user for most of her or his processing needs. Programs for the client and extra processing capacity are provided as needed by the network.
Server. A server is a host or central computer that is dedicated to managing the logistics of routing data, information, and processing capacity among the clients on the system. In small networks, the server might be a single PC. On larger networks, the server can be a minicomputer or a mainframe. In very large organizations, several networks might be served, each by their own minicomputer, which in turn, is linked to the host mainframe.
Teaching Tips
This slide relates to the material on pp. 100.
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9. Computer System Components
Central Processing Unit
Output
Devices
Cache
Memory
Primary
Storage
Secondary
Control
Unit
ALU
Special
Purpose
Processors
Input
A typical computer system has the following components:
Input. The input devices of a computer system include keyboards, touch screens, pens, electronic "mice," optical scanners, and other peripheral hardware components that convert data into electronic machine-readable form. Input may be direct entry (by the end user) or through telecommunications links.
Processing. The central processing unit (CPU) is the main processing component of a computer system. The CPU is divided into two major components: the arithmetic-logic unit (ALU), which performs the arithmetic and logic functions required in computer processing, and the control unit, which interprets computer program instructions and transmits directions to the other components of the computer system. The CPU also contains circuitry for devices such as registers and cache memory, used for high speed temporary storage of data and instructions.
Output. Output devices convert the electronic information produced by the computer system (binary or digital information) into human-intelligible form for presentation to end users. Output devices include video display units, printers, audio response units, and other peripheral hardware components specialized in this function.
Storage. Storage devices store data and program instructions needed for processing. A computer's primary storage or memory is used to hold key information needed to run the computer while secondary storage (such as magnetic disks and tape units) hold larger parts of programs used less frequently and the content files created by end users.
Teaching Tips
This slide corresponds to Figure 3.13 on p. 105 and relates to the material on pp
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10. Input Technology Trends
First
Generation
Second
Third
Fourth
Fifth
Punched
Cards
Paper Tape
Key to Tape/
Disk
Keyboard Data Entry
Pointing Devices
Optical Scanning
Voice Recognition
Speech and
Touch Devices
Handwriting
Recognition
Trend: Towards Direct Input Devices that Are More Natural
and Easy to Use
This figure emphasizes that there has been a major trend toward the increased use of input technologies that provide a more natural user interface for computer users. You can now enter data and commands directly and easily into a computer system through pointing devices like electronic mice and touch pads, and technologies like optical scanning, handwriting recognition, and voice recognition. These developments have made it unnecessary to always record data on paper source documents (such as sales order forms, for example), and then keyboard the data into a computer in an additional data entry step. Further improvements in voice recognition and other technologies should enable an even more natural user interface in the future.
Teaching Tips
This slide corresponds to Figure 3.17 on p. 109 and relates to the material on pp
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11. Common Input Devices Keyboard Pointing Devices Pen Based Computing
Speech Recognition
Optical Scanning
Magnetic Ink Character Recognition
Smart Cards
Digital Cameras
Let’s take a moment to review some of the more popular means and devices used for capturing input.
Keyboards. Are the most widely used devices for entering data and text.
Pointing Devices. Are widely used with operating systems that have a graphical user interface. They include a range of devices:
Electronic mouse
Trackball
Pointing stick-- a small button-like device centered on a row above the keyboard in some notebook PCs.
Touchpads-- rectangular touch-sensitive surface usually below the keyboard, found in notebook PCs
Touch screens-- devices that allow you to use a computer by touching the face of its video display screen.
Pen-based Computing Devices. Are used in many handheld computers. These computers use special software to recognize and digitize handwriting and drawings using a stylus.
Speech Recognition Systems. Use software to digitize, analyze, and classify your speech and its sound patterns. Recognized words are then passed to your application software.
Optical Scanning. Are devices that read text or graphics and convert them into digital input. There are various types of optical scanning devices including:
Desktop Scanners-- used with PCs to capture images
Optical Character Recognition (OCR)-- reads special OCR characters and codes on documents
Magnetic Ink Character Recognition (MICR). Used by the banking industry to read checks. Uses special ink and a special reader to read bank and customer identification data written on the bottom of the check.
Magnetic Stripe. Uses a magnetic stripe on the back of cards to store up to 200 bytes of data. Data is read using a magnetic stripe reader.
Smart Cards. Embeds a microprocessor chip with several kilobytes of memory.
Digital Cameras. Enables you to capture and store still photos or full motion video in digital form.
Teaching Tips
This slide relates to the material on pp
Ask students to describe everyday applications of these devices. How are they used in business?
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12. Output Technology Trends
First
Generation
Second
Third
Fourth
Fifth
Punched
Cards
Printed Reports
and Documents
Video Displays
Audio Responses
Voice Responses
Hyperlinked
Multimedia
Documents
Trend: Towards Output Methods that Communicate Naturally,
Quickly, and Clearly
This figure shows you the trends in output media and methods that have developed over the generations of computing. As you can see, video displays and printed documents have been, and still are, the most common forms of output from computer systems. But other natural and attractive output technologies such as voice response systems and multimedia output are increasingly found along with video displays in business applications.
For example, you have probably experienced the voice and audio output generated by speech and audio microprocessors in a variety of consumer products. Voice messaging software enables PCs and servers in voice mail and messaging systems to interact with you through voice responses. And of course, multimedia output is common on web sites of the Internet and corporate intranets.
Teaching Tips
This slide corresponds to Figure 3.23 on p. 114 and relates to the material on p.114.
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13. Common Output Devices Video Output Printed Output CRT LCD Inkjet Laser
Computers provide information to users in a variety of forms.
Video displays. Is the most common form of computer output. Most desktop computers use a cathode ray tube (CRT) video display. Another type of display is called liquid crystal display (LCD). These are used mostly in portable and handheld computers, although LCD for PC desktops is growing in popularity. LCDs require less electricity and provide a thin flat display.
Printed Output. Printed output is the next most popular form of computer output. Most personal computers rely on either inkjet printers or laser printers.
Teaching Tips
This slide relates to the material on pp
Ask students to describe the advantages and disadvantages of both types of printers.
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14. Storage Trends First Generation Second Third Fourth Fifth Magnetic
Drum
Core
LSI
Semiconductor
Memory Chips
VLSI
Trend: Towards Large Capacities Using Smaller Microelectronic Circuits
Trend: Towards Massive Capacities Using Magnetic and Optical Media
Magnetic Tape
Magnetic Drum
Magnetic Disk
Optical Disk
Primary
Storage
Secondary
Data and information must be stored until needed using a variety of storage methods. For example, many people and organizations still rely on paper documents stored in filing cabinets as a major form of storage media. However, you and other computer users are more likely to depend on the memory circuits and secondary storage devices of computer systems to meet your storage requirements.
Figure 3.26 illustrates major trends in primary and secondary storage methods. Progress in very-large-scale integration (VLSI), which packs millions of memory circuit elements on tiny semiconductor memory chips, is responsible for continuing increases in the main-memory capacity of computers. Secondary storage capacities are also expected to escalate into the billions and trillions of characters, due primarily to the use of optical media.
Teaching Tips
This slide corresponds to Figure 3.26 on p.117 and relates to the material on pp
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15. Primary & Secondary Storage Media
Semiconductor
Memory
Magnetic
Disks
Floppy Disk
Hard Disk, RAID
Magnetic Tape
Optical Disks
CD-ROM, CD-R
CD-RW
DVD
Access Speed Increases
Storage Capacity Decreases
Cost per Bit Increases
Direct
Access
Sequential
Secondary Storage
Primary
Storage
Data and information need to be stored after input, during processing, and before output. The figure on the slide illustrates the speed, capacity, and cost relationships of several alternative primary and secondary storage media. High speed storage media cost more per byte and provide lower total capacities. Conversely, large-media storage is less expensive but slower. Storage media also differ in how they are accessed by the computer:
Direct Access. Primary storage media such as semiconductor memory chips and secondary storage devices like magnetic disks and optical disks have direct access. This means that any element of data can be directly stored and retrieved by the CPU by selecting and using any of the locations on the storage media. Each location is unique and is available to the CPU independently of other stored elements.
Sequential Access. Sequential access storage media such as magnetic tape do not have unique storage addresses. Instead, data must be stored and retrieved using a sequential or serial process. Locating an individual item of data requires searching from the beginning of the sequence procedure through all of the data elements that proceed it in the sequence.
Semiconductor Memory. The primary storage of your computer is composed of microelectronic semiconductor memory chips. This includes specialized memory like external cache memory and flash memory. There are tow types of semiconductor memory:
Random Access Memory (RAM). Volatile memory that can be sensed (read) and changed written).
Read Only Memory (ROM). Nonvolatile memory that are used for permanent storage.
Magnetic Disk. The most common form of secondary storage consists of metal or plastic disks covered with an iron oxide recording material. Data are recorded on tracks in the form of magnetized spots to form binary digits. Electromagnetic read/write heads, positioned by access arms are used to read and write data. The two most popular forms of magnetic disks are floppy disks and hard disks.
Redundant Arrays of Independent Disks (RAID). Are disk arrays of interconnected microcomputer hard disks to provide many gigabytes of online storage.
Magnetic Tape. Sequential access secondary storage that uses read/write heads within magnetic tape drives to read and write data in the form of magnetized spots on the iron oxide plastic coating of plastic tape. Magnetic tape devices include tape reels and cartridges in mainframes and midrange systems, and small cassettes or cartridges for PCs. Magnetic tape is most often used for archival storage and backup.
Optical Disk Storage. Are a popular storage medium for image processing that records data by using a laser to burn pits in a plastic disk and reads data by using a laser to read the binary codes formed by those pits. There are several different types of optical disks.
Compact Disk-Read Only Memory (CD-ROM)-- each disk can store more than 600MB.
Compact Disk Recordable (CD-R)-- Enables users to record their own data once on a CD, and read the data indefinitely.
Compact Disk Rewriteable (CD-RW)-- Enables users to record and erase (rewrite) data.
Digital Video Disk (DVD)-- each disk can store from 3.0 to 8.5 GB of data on each side of a compact disk. It is expected that DVD will replace CD-ROM and CD-RW technologies.
Teaching Tips
This slide corresponds to Figure 3.27 on pp. 117 and relates to the material on pp
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16. Characteristics of Magnetic Disks
This slide corresponds to Figure 4.36 on pp. 158 and relates to the material on pp
Cylinders
Access
Mechanism
Arms
Read/Write
Heads
Disks
Tracks: Concentric circles
for storing data as magnetized
bits.
Sectors:
Portions of a track
Track
Magnetic disks are the most common form of secondary storage for modern computer systems. Magnetic disks are thin metal or plastic disks that are coated on both sides with an iron oxide recording material. Several disks can be mounted together vertically to increase storage capacity. Electromagnetic read/write heads are positioned by access arms between the slightly separated disks to read and write data on concentric, circular tracks (the unique addresses for each data element). The most popular forms of magnetic disks include:
Floppy Disks. Also called magnetic diskettes, these consist of polyester film disks covered with an iron oxide compound. A single disk is mounted and rotates freely inside a protective flexible or hard plastic jacket. Floppies are extremely portable, a 3.5" disk fitting into a shirt pocket.
Hard Disk Drives. The "hard drive" combines several magnetic disks, access arms, and read/write heads into a sealed module. This allows higher speeds, greater data-recording densities, and closer tolerances within a sealed, more stable environment.
RAID. RAID stands for redundant arrays of inexpensive disks. They combine from 6 to over 100 small hard disk drives and their microprocessors into a single unit. RAIDs provide large capacities with high speed access via parallel multiple paths from many disks. They are also fault tolerant in that more than one copy of the data exists. If a track, sector, or disks fails, backup is possible from one of the redundant disks.
Teaching Tip: RAIDs are kind of a high-tech/low-tech inexpensive solution to large storage capacity needs.
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17. Chapter Summary
A computer system is a system of information processing components that perform input, processing, output, storage and control functions.
The hardware components in a computer include input and output devices, a central processing unit (CPU), and primary and secondary storage.
There are three major categories of computers: microcomputers, midrange computers and mainframe computers
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18. Chapter Summary (cont)
Microcomputers are used as personal computers, but are also interconnected in a variety of telecommunications networks.
Midrange computers are increasingly being used as powerful network servers and for many multi-user business data processing and scientific applications.
Mainframe computers are larger and more powerful and are used to handle information processing needs for large organizations .
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19. Chapter Summary (cont)
Peripheral devices used for input and output come in a variety shape and sizes. Future trends are towards devices that communicate naturally and are quick and easier to use.
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