3 Computer Hardware © 2002 McGraw-Hill Companies

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. Identify the computer systems and peripherals you would acquire or recommend for a business of your choice, and explain the reasons for your selections. © 2002 McGraw-Hill Companies

Computer System Categories Mainframe Computers Midrange Microcomputers Traditionally, computer systems are classified as microcomputers, midrange computers, and mainframe computers. However, these distinctions are not so clear as a few years ago. Improvements in technology make microcomputers more powerful than ever and both minis and mainframes have lower and higher end versions. 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. Most microcomputer 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 back room order processing) without having to share time on an organization's larger mainframe. Of course, many small and medium-sized organizations use such computer 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 million instructions per second - MIPS). Teaching Tips This slide corresponds to Figure 3.2 on pp.72 and relates to the material on pp. 71 -72. © 2002 McGraw-Hill Companies

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 (1951-1958) 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 (1959-1963) 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 (19654-1979) 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.73 and relates to the material on pp. 72-73. © 2002 McGraw-Hill Companies

Microcomputer Systems Handheld Computers PDA, Information Appliances Notebook Computers Desktop Computers Workstations Network Server Powerful microcomputer used in small LANs Microcomputers are the most important category of computer systems for businesspeople and consumers. Though usually called a personal computer, or PC, a microcomputer is much more than a small computer for use by an individual. The computing power of microcomputers now exceeds that of the mainframes of previous computer generations at a fraction of their cost. Thus, they have become powerful networked professional workstations for business professionals. PDA - is a hand-held microcomputer device that enable you to manage information such as appointments, to-do lists, and sales contacts, send and receive E-mail, access the Web, and exchange such information with your desktop PC or network server. Information Appliances - Small Web-enabled microcomputer devices with specialized functions, such as hand-held PDAs, TV set-top boxes, game consoles, cellular and PCS phones, wired telephone appliances, and other Web-enabled home appliances. Notebook computer - A computer that is designed for those who want a small portable PC for their work activities. Desktop computer - A computer that is designed to fit on an office desk. Workstation - (1) A computer system designed to support the work of one person. (2) a high-powered computer to support the work of professionals in engineering, science, and other areas that require extensive computing power and graphics capabilities. Network Servers - These powerful microcomputers are used to coordinate telecommunications and resource sharing in small local area networks and Internet and intranet websites. Teaching Tips This slide relates to the material on pp. 73-75. © 2002 McGraw-Hill Companies

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. 74 - 76 © 2002 McGraw-Hill Companies

Computer System Components Central Processing Unit Output Devices Cache Memory Primary Storage Secondary Control Unit ALU Special Purpose Processors Input A computer system is an interrelated combination of components performing specialized basic functions to provide end users with a powerful information processing tool. Key functions include: Input. The input devices of a computer system include keyboards, touch screens, pens, electronic "mice," optical scanners, and other peripheral hardware components that convert electronic 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. A key component of the CPU is the arithmetic-logic unit (ALU), which performs the arithmetic and logic functions required in computer processing. 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 programs 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. Control. The control unit of the CPU interprets computer program instructions and transmits directions to the other components of the computer system. © 2002 McGraw-Hill Companies

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 Touch Devices Handwriting 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 3.15 on p.84 and relates to the material on pp.84-89. © 2002 McGraw-Hill Companies

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. 84-89. Ask students to describe everyday applications of these devices. How are they used in business? © 2002 McGraw-Hill Companies

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 3.21 on p. 90 and relates to the material on p.90-98. © 2002 McGraw-Hill Companies

Common Output Devices Video Output Printed Output CRT LCD Inkjet Laser 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. Video images can serve as input as well as output. TV signals or photographs can be digitized and used by the computer. Video displays are the most common type of computer output. Typical video displays include: Cathode Rate Tube (CRT). Most video displays use a cathode ray tube technology similar to the picture tubes used in home TV sets. Although the clarity of the display is dependent upon the graphic capability of the computer, CRTs are capable of a very high level of clarity. This is especially important for graphics-intensive work needed in research and development and visual presentations. Liquid Crystal Displays (LCDs). LCDs are the same technology used in electronic calculators and digital watches. LCDs can be made small and require very little current to operate, making them ideal for portable devices. Plasma Displays. Plasma displays are generated when electrically charged particles of gas are trapped between glass plates. These displays produce very high quality graphics on a flat service at faster speeds than LCDs. They are much more expensive than LCD output but necessary in portable computers that require very high resolution video output, such as full motion video and full color business presentations. Printed output on paper is still the most common form of output after video displays. Inkjet printers: spray ink onto a page one line at a time. Laser printers: use an electrostatic process similar to a photocopying machine to produce many pages per minute of high-quality output. Teaching Tips This slide relates to the material on pp.90-91. Ask students to describe the advantages and disadvantages of both types of printers. © 2002 McGraw-Hill Companies

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 3.24 on p.92 and relates to the material on pp.91-92. © 2002 McGraw-Hill Companies

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 3.25 on pp. 93 and relates to the material on pp.93-98. © 2002 McGraw-Hill Companies

Characteristics of Magnetic Disks 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. © 2002 McGraw-Hill Companies

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 © 2002 McGraw-Hill Companies

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 . © 2002 McGraw-Hill Companies

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. © 2002 McGraw-Hill Companies