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‫كلية تكنولوجيا العلوم الصحية التطبيقية‬ ‫‪An Introduction to‬‬ ‫‪Computer science‬‬ ‫‪2025‬‬ ‫‪1‬‬  The Introduction Computer technology has transformed our lives for over 50 years. First introduced to alleviate the tedious work of...

‫كلية تكنولوجيا العلوم الصحية التطبيقية‬ ‫‪An Introduction to‬‬ ‫‪Computer science‬‬ ‫‪2025‬‬ ‫‪1‬‬  The Introduction Computer technology has transformed our lives for over 50 years. First introduced to alleviate the tedious work of calculating long data tables for the military, we now find computers recording and processing every aspect of our daily activity. The modern computer is no longer just a numeric calculator; it is a multimedia device that displays images, sound, and video through operating systems and applications that give the user unprecedented control over information. Visionaries such as Alan Turing and Vannevar Bush articulated the direction for such computers, but it was the development of micro- electronics that brought multimedia to our desktops. Powerful computing devices make multimedia applications possible. They capture and convert input from various analog sources, process and store the digital data, and output in ways that empower users to create, distribute, search, and share information as never before. Hardware powers the development and delivery of multimedia. Computer as a revolution left no area of life untouched in the present world. It is of tremendous help in all field of life. Hence, the knowledge of computer is a necessity for existence of everybody in this global village. The invention of computer has transformed our simple manual works to sophisticated life of automated works to meet the global demand for the higher productivity and increased efficiency with high precision. Computer is increasingly becoming compulsory in nearly all fields of studies, not because of anything but its accuracy and versatility in processing data. Many tasks at home or office are being automated rapidly with computer. Thus it is becoming apparent that in whatever discipline or working sector, the computer is now a very vital tool for efficiency improvement and precision of job or task execution. This is designed to meet the prerequisite need of everybody that are interested and wish to know about computers science and computing in general. A computer is an electronic device, operating under the control of instructions stored in its own memory. These instructions tell the machine what to do. The computer is capable of accepting data (input), processing data arithmetically and logically, producing output from the processing, and storing the results for future use. Most computers that sit on a desktop are called Personal Computers (PCs). The "computer" is an ensemble of different machines that you will be using to get your job done. A computer is primarily made of the Central Processing Unit (usually referred to as the computer), the monitor, the keyboard, and the mouse. Other pieces of hardware are commonly referred to as peripherals. 2 In everyday life activities, we process data or encounter cases of data processing. A typical example of data processing is the generation of statement of student result from the marks score in an examination and continuous assessment. It is essential to know that information is as good as the data from which it is derived, and the transformation process which they are subjected to. Meaningless data or inappropriate processing produces wrong information. Thus computer gives you results corresponding to what data you supply and how you process it (i.e. ëgabbage- in, gabbage-outí). Summarily, the intelligent performance of a computer depends on correctness of input data and the intelligence performance of the human being that drives it. USES OF COMPUTERS People use computers in many ways; business, computers are used to track inventories with bar codes and scanners, check the credit status of customers, and transfer funds electronically, homes, tiny computers embedded in the electronic circuitry of most appliances control the indoor temperature, operate home security systems, tell the time, and turn video cassette recorders (VCRs) on and off, automobiles regulate the flow of fuel, thereby increasing gas mileage, they also entertain, creating digitized sound on stereo systems or computer-animated features from a digitally encoded laser disc. Computer programs, or applications, exist to aid every level of education, from programs that teach simple addition or sentence construction to programs that teach advanced calculus. Educators use computers to track grades and communicate with students; with computer-controlled projection units, they can add graphics, sound, and animation to their communications. Computers are used extensively in scientific research to solve mathematical problems, investigate complicated data, or model systems that are too costly or impractical to build, such as testing the air flow around the next generation of aircraft. The military employs computers in sophisticated communications to encode and unscramble messages, and to keep track of personnel and supplies. HISTORY OF COMPUTING Since the creation of man, a significant amount of human activities has been ascribed to organizing and processing information so that it could be more easily presented for easy comprehension. Many devices have been used in the past before the advert of computer. It is then necessary to vividly look into their evolution. Early computing machines: 3 1. Abacus (-2500BC): This is a hand- held device made of beads stung on rods in a frame. The rods correspond to positions of the digits while the beads correspond to the digits. 2. Napierís Bone (2500BC): This was invented by John Napierís (1550 - 1617). This consists of small rods with appropriate markings on them. It is a mechanical aid to computation that consists of nine such rods (called bones) with one for each digit 1 through 9. He also invented logarithms which made possible to do division and multiplication by performing addition and subtraction. 3. Slide Rule (1600AD) by William Oughtred (1575 - 660): He invented it in 1622 but announced it in 1632 this consist of rules on which markings represent logarithms of numbers and also permits calculation involving exponents, trigonometric functions, etc. 4. Pascal mechanical calculator (1600) or Numerical wheel calculator:-Blaise Pascal (1623 -1664) in 1642 invented the first adding machine called Pascaline. The brass rectangular box used eight moveable dials to add and sum up of eight figures long using base 10. It can perform all the four arithmetic operation with previous unheard speed. 5. Leibnitz mechanical multiplier (1600): In 1694 Gottfried Wilhem Von Leibnitz (1646 -1716) improved upon the pascaline by creating a machine that can also multiply using a system of dials and gear. 6 Colmarís Calculator (1820) by Charles Xavier Thomas de Colmar: This presented a more practical approach to computing. 7 Punched-Card machine (Jacquardís loom) (1801): Joseph Marie Jacquard. 8 Mechanical computer: Charles Gabbage (1792-1871) Father of the computer. Difference engine powered by steam and large as locomotive the machine has a stored program and could perform calculations and print the result automatically. We also have Analytical engine credited to him. 9 Hermann Hollerith (1860-1929)  Hollerithís system punch-card reader machine:-for counting census result in 1890 in US.  formed tabulating machine company in 1896(TMC)  Automatic Tabulating Machine (ATM)-1900  TMC was renamed to International Business Machines Corporation (IBM) in 1924 after series of mergers. In summary, the history of computing began with an analog machine. In 1623 German scientist Wilhelm Schikard invented a machine that could add, and with the aid of logarithm tables, multiply and divide. Since then the development has pass through a lot of stages such as the invention of punched cards to program patterns to create woven fabrics by Joseph-Marie Jacquard a French inventor in 19th century. Another early mechanical computer was the Difference Engine, designed in the early 1820s by British 4 mathematician and scientist Charles Babbage. In the 1930s American mathematician Howard Aiken developed the Mark I calculating machine, which was built by IBM. This electronic calculating machine used relays and electromagnetic components to replace mechanical components. To be sincere, the world has left the era of hearing stories about computer. We are now in the world of what you can use it for to serve its desired purposes. Categories of Computers Industry experts typically classify computers in seven categories: personal computers (desktop), mobile computers and mobile devices, game consoles, servers, mainframes, supercomput- ers, and embedded computers. A computer’s size, speed, processing power, and price deter- mine the category it best fits. Due to rapidly changing technology, however, the distinction among categories is not always clear-cut. This trend of computers and devices with technolo- gies that overlap, called convergence, leads to computer manufacturers continually releasing newer models that include similar functionality and features. For example, newer cell phones often include media player, camera, and Web browsing capabilities. As devices converge, users need fewer devices for the functionality that they require. When consumers replace outdated computers and devices, they should dispose of them properly. Figure 1-14 summarizes the seven categories of computers. The following pages discuss computers and devices that fall in each category. Number of Simultaneously Category Physical Size Connected Users General Price Range Personal computers Fits on a desk Usually one (can be more Several hundred to several (desktop) if networked) thousand dollars Mobile computers and Fits on your lap or in your Usually one Less than a hundred dollars mobile devices hand to several thousand dollars Game consoles Small box or handheld One to several Several hundred dollars or device less Servers Small cabinet Two to thousands Several hundred to a million dollars Mainframes Partial room to a full room Hundreds to thousands $300,000 to several million of equipment dollars Supercomputers Full room of equipment Hundreds to thousands $500,000 to several billion dollars Embedded computers Miniature Usually one Embedded in the price of the product This table summarizes some of the differences among the categories of computers. These should be considered general guidelines only because of rapid changes in technology. 5  The term, PC-compatible, refers to any personal Personal Computers computer based on the original IBM personal computer design. A personal computer is a computer that can perform all of its Companies such as Dell, HP, and Toshiba sell input, processing, output, and storage activities by itself. A PC-compatible computers. PC and personal computer contains a processor, memory, and PC-compatible computers usually use a one or more input, output, and storage devices. Personal Windows operating system. Apple computers computers also often contain a communications device. usually use a Macintosh operating system (Mac Two popular architectures of personal computers are the PC OS). (Figure 1-15) and the Two types of personal computers are desktop computers and notebook computers. Figure 1-2 PC and PC-compatible computers usually use a Figure 1-3 Apple computers, such as the iMac, Windows operating system. usually use a Macintosh operating system. 6  Mobile Computers and Are PCs or Apple computers more popular? Mobile Devices A mobile computer is a personal computer you have been rising consistently during the past few years. In fact, Apple com- can carry from place to place. Similarly, a mobile device is a computing device small enough to hold in your hand. The most popular type of mobile computer is the www.cengagebrain.com, navigate to the Chapter 1 FAQ resource for this book, notebook computer. The following sections and then click Personal Computer Sales. discuss the notebook computer and widely used mobile devices. Desktop Computers A desktop computer is designed so that the system unit, input devices, output devices, Notebook Computers and any other devices fit entirely on or under a desk or table (Figures 1-15 and 1-16 on A notebook computer, also called a laptop the previous page). In many models, the system unit is a tall and narrow tower, which computer, is a portable, personal computer often can sit on the floor vertically — if desktop space is limited. designed to fit on your lap. Notebook computers Some desktop computers function as a server on a network. Others, such as a gaming are thin and lightweight, yet they can be as pow- desktop computer and home theater PC, target a specific audience. The gaming desktop erful as the average desktop computer. A netbook, computer offers high-quality audio, video, and graphics with opti- mal performance for which is a type of notebook computer, is smaller, sophisticated single-user and networked or Internet multiplayer games. A home theater PC lighter, and often not as powerful as a traditional (HTPC) combines the features of a high-definition video/audio entertainment system with a notebook computer. Most netbooks cost less than desktop computer that is designed to be connected to a television and includes a Blu-ray traditional notebook computers, usually only a few Disc, digital video recorder, and digital cable tele- vision connectivity. These high-end hundred dollars. An ultra-thin is another type of computers cost more than the basic desktop computer. notebook computer that is lightweight and usually Another expensive, powerful desktop computer is the workstation, which is geared for less than one-inch thick. Some notebook computers work that requires intense calculations and graphics capa- bilities. An architect uses a have touch screens, allowing you to interact with workstation to design buildings and homes. A graphic artist uses a workstation to the device by touching the screen, usually with the create computer-animated tip of a finger. special effects for full-length motion pictures and video games. On a typical notebook computer, the keyboard is on top of the system unit, and the monitor attaches to the system unit with hinges (Figure 1-17). These computers weigh on average from 2.5 to more than 10 pounds (depending on configuration), which allows users to transport the computers from place to place. Most notebook computers can operate on batteries or a power supply or both. display keyboard hinge optical disc drive Figure 1-4 On a typical notebook computer, the keyboard is on top of the system unit, and the display attaches to the system unit with hinges. 7 Tablet PCs Resembling a letter-sized slate, to exchange information between the computer the Tablet PC, or tablet computer, is a spe- cial type of and the mobile device. notebook computer that you can interact with by touching the Some mobile devices are Internet-enabled, screen with your finger or a digital pen. A digital pen looks like meaning they can connect to the Internet a small ink pen but uses pressure instead of ink. Users write or wirelessly. With an Internet-enabled device, draw on a Tablet PC by pressing a finger or digital pen on the users can chat, send e-mail and instant mes- screen, and issue instructions by tapping on the screen. One sages, and access the Web. Because of their design of Tablet PC, called a convertible tablet, has an attached reduced size, the screens on mobile devices are keyboard. Another design, which does not include a small, but usually are in color. keyboard, is called Popular types of mobile devices are smart a slate tablet (Figure 1-18) and provides other means for phones and PDAs, e-book readers, handheld typing. Some Tablet PCs also sup- port voice input so that computers, portable media players, and digital users can speak into the computer. cameras. Tablet PCs are useful especially for taking notes in lectures, at meetings, conferences, and other forums where the standard Smart Phones and PDAs Offering the notebook computer is not practical. convenience of one-handed operation, a smart phone (Figure 1-19) is an Internet-enabled phone that usually also provides personal information management functions such as a calendar, an appointment book, an address book, a calculator, and a notepad. In addition to basic phone capa- bilities, a smart phone allows you to send and receive e- mail messages and access the Web — usually for an additional fee. Some smart phones communicate wirelessly with other devices or computers. Many also function as a portable media player and include built-in digital cameras so that you can share photos or videos with others as soon as you capture the Figure 1-5 The iPad is a widely used slate tablet. image. Many smart phones also offer a variety of Mobile Devices application software Mobile devices, which are small enough to carry in a such as word processing, pocket, usually do not have disk drives. Instead, these spreadsheet, and games, devices store programs and data permanently on special and the capability of memory inside the system unit or on small storage conducting live video conferences. Many smart phones have keypads that con- tain both numbers and letters so that you can media such as memory cards. You often can connect a mobile use the same keypad to Figure 6 Some smart phones have touch screens; device to a personal computer dial phone numbers others have mini keyboards. 8  and enter messages. Others have a built-in mini E-Book Readers An e-book reader (short keyboard on the front of the phone or a key- board for electronic book reader), or e-reader, is a that slides in and out from behind the phone. Some handheld device that is used primarily for read- have touch screens, where you press objects on the ing e-books (Figure 1-20). An e-book, or digi- tal screen to make selections and enter text through an book, is an electronic version of a printed book, on-screen keyboard. Others include a stylus, which readable on computers and other digital devices. is similar to a digital pen but smaller and has less In addition to books, users typically can purchase. functionality. and read other forms of digital media such as Instead of calling someone’s smart phone or cell newspapers and magazines. phone, users often send messages to others by Most e-book readers have a touch screen and are pressing buttons on their phone’s keypad, keys on Internet-enabled. These devices usually are smaller the mini keyboard, or images on an on- screen than tablet computers but larger than smart phones. keyboard. Types of messages users send with smart phones include text messages, instant messages, picture messages, and video messages. A text message is a short note, typically fewer than 300 characters, sent to or from a smart phone or other mobile device. An instant message is a real-time Internet communication, where you exchange messages with other connected users. A picture message is a photo or other image, sometimes along with sound and text, sent to or from a smart phone or other mobile device. A phone that can send picture messages often is called a camera phone. A video message is a short video clip, usually about 30 seconds, sent to or from a smart phone or other mobile device. A phone that can send video messages often is called a Figure 1-7 An e-book reader. video phone. A PDA (personal digital assistant), which often looks Handheld Computers A handheld like a smart phone, provides personal information computer, sometimes referred to as an management functions such as a calendar, an Ultra-Mobile PC (UMPC ), is a computer small appointment book, an address book, a calculator, enough to fit in one hand. Many handheld and a notepad. A PDA differs from a smart phone in computers communicate wirelessly with other that it usually does not provide phone capabilities devices or computers and also include a digital and may not be Internet- enabled, support voice pen or stylus for input. input, have a built-in camera, or function as a Some handheld computers have miniature or portable media player. specialized keyboards. Many handheld As smart phones and PDAs continue a trend of computers are industry-specific and serve the convergence, it is becoming increasingly dif- ficult needs of mobile employees, such as meter to differentiate between the two devices. This has readers and parcel delivery people (Figure 1- led some manufacturers to refer to PDAs and smart 21), whose jobs require them to move from phones simply as handhelds. place to place. 9 Some portable media players are Internet- enabled so that you can access Web sites and send e-mail messages directly from the device. Many offer personal information management functions such as a calendar and address book, and include a variety of games and other appli- cation software. Portable media players usually include a set of earbuds, which are small speakers that rest inside each ear canal. Some portable media players have a touch screen, while others have a touch-sensitive pad that you operate with a thumb or finger, to navigate through digital media, adjust volume, and customize settings. Digital Cameras A digital camera is a device that allows users to take pictures and store the photographed images digitally, instead of on traditional film (Figure 1-23). While many digital cameras look like a traditional camera, some are built into smart phones and other mobile devices. Portable Media Players Although digital cameras usually have some A portable media player is a mobile device on which you amount of internal storage to hold images, most can store, organize, and play digital media (Figure 1-22). For users store images on small storage media such as example, you can listen to music; watch videos, movies, and memory cards. Digital cameras typically allow users television shows; and view photos on the device’s screen. to review, and sometimes modify, images while they With most, you download the digital media from a computer are in the camera. Some digital cam- eras connect to to the portable media player or to media that you insert in or communicate wirelessly with a computer or the device. printer, allowing users to print or view images directly from the printer. Some memory cards can connect to a network wire- lessly, so that you can transfer photos directly from the memory card in the camera to the Internet without requiring a computer. Often users prefer to download images from the digital camera to the computer. Or, you can remove the storage media such as a memory card from the digital camera and insert it in a card reader in or attached to the computer. Figure 1-8 The iPod, shown here, is a popular portable media player. Figure 1-9 With a digital camera, users can view photographed images immediately through a small screen on the camera to see if the picture is worth keeping.. 10 Servers A server controls access to the hardware, software, and other resources on a network and provides a centralized storage area for programs, data, and information (Figure 1-25). Servers can support from two to several thousand connected computers at the same time. In many cases, one server accesses data, infor- mation, and programs on another server. In other cases, people use personal computers or terminals to access data, information, and pro- grams on a server. A terminal is a device with a monitor, keyboard, and memory. Mainframes A mainframe is a large, expensive, powerful computer that can handle hundreds or thou- sands of connected users simultaneously (Figure 1-26). Mainframes store tremendous amounts of data, instructions, and information. Most major corporations use mainframes for business activi- ties. With mainframes, enterprises are able to bill millions of customers, prepare payroll for thousands of employees, and manage thousands of items in inventory. One study reported that mainframes process more than 83 percent of transactions around the world. Mainframes also can act as servers in a network environment. Servers and other mainframes can access data and information from a mainframe. People also can access programs on the main- frame using terminals or personal computers. Supercomputers A supercomputer is the fastest, most powerful computer — and the most expensive (Figure 1-27). The fastest supercomputers are capable of processing more than one quadrillion instruc- tions in a single second. With weights that exceed 100 tons, these computers can store more than 20,000 times the data and information of an average desktop computer. Applications requiring complex, sophisticated mathematical calculations use supercomputers. Large-scale simulations and applications in medi- cine, aerospace, automotive design, online bank- ing, weather forecasting, nuclear energy research, and petroleum exploration use a supercomputer. 11 Chapter One: The Essentials Chapter Objectives:  Learn the difference between hardware and software  Discover the various types of computers and their roles  See what’s on the front, back, and inside of a computer  Learn about the various ports on a computer  Understand what determines a computer’s performance  See what you should look for when buying a computer Computers are useful: they help us write letters, find information on the Internet, and even create our own music CDs. Some people love computers—they speak a different language that includes nonsensical words like IP address and gigabytes. But most of us are somewhat clueless when it comes to computers. We know how to turn our computer on, how to surf the Internet (maybe), and how to write a quick letter on a word processor. But that’s about it—we have to ask our kids or friends for help when something goes wrong, which is all the time. This guide takes some of the mystery out of computers. In this chapter we’ll take a good hard look at a computer from the front, back, and yes, even inside. You’ll understand what all those confusing ports on the back of the computer are for and why it’s important for your computer to have a fast CPU. Best of all, we’ll explain all of this in simple terms, so you won’t need an engineering degree to understand everything. Ready to tackle your computer? Great—turn the page and let’s get started… 12  Lesson 1-1: Hardware, Software, and Information Technology (IT) Figure 1-11 A typical computer setup Figure 1-12 Microsoft Word is an example of a software application. Figure 1-1 Your desk probably contains a jumble of equipment commonly known as a computer. But what is all that stuff? What does a computer do? Unlike many other tools or appliances that have limited purposes, a computer can do any number of things:  Write letters  Browse the Internet  Send e-mail messages to people around the world  Play games  Help you balance your budget …and that’s just the beginning of what you can do with a computer! 13  Two basic components make up a computer: hardware and software. You simply can’t have one without the other. All computer parts that you can physically see or touch are called hardware. Hardware includes the computer’s monitor, case, keyboard, mouse, and printer. Computer programs that tell hardware how to operate are called software. You may have used software such as Microsoft Excel or Corel WordPerfect in the past. So breathe a giant sigh of relief—you don’t have to know how to program a computer to use one. A computer programmer has already done the work for you by writing the program (software). All you have to do is tell the software what you’re trying to do, and the software then directs the work of the hardware. Figure 1-1 shows an example of a typical computer setup and its components, but don’t Your computer setup worry if your setup is different. More than likely, you have all the parts that you need, and may differ from the one shown in Figure those parts are properly connected. In any case, Table 1-1: Parts of a Computer, provides 1-1. For example, you more details about each individual component. might have a computer IT, short for Information Technology, is the broad subject related to computers and case that is tall and managing and processing information, especially within large organizations. Many large skinny (tower case) or companies have departments full of computer experts called IT departments. a flat screen monitor. Table 1-1: Parts of a Computer Component Description Case or System The main computer box, technically known as the system unit, is the most Unit important part of a computer. It contains the guts and brains of the computer— something we‘ll talk about later. The system unit contains a lot of holes or ports where you plug in the rest of the computer system. Monitor The monitor resembles a television set, and is where the computer displays information. Keyboard The keyboard is the thing you type on to tell your computer what to do. Mouse Like the keyboard, the mouse is another input device that you use to communicate with your computer. Speakers Most computers can make sounds, just like a stereo system. In fact, you can even listen to audio CD‘s on most computers or watch DVDs. Printer A printer is where a computer writes down information or output, onto paper, or a hardcopy. 14  Lesson 1-2: Computer Overview Figure 1-13 How a computer works. Figure 1-14 Comparing a TV to a PC. Input Process/Storage Output The computer processes data, The computer communicates You communicate with the makes calculations, directs its results to you via an output computer via an input device the work of the hardware, and device such as a monitor, a such as a mouse, a keyboard, stores your files. printer, or speakers. or a joystick. Input The remote control talks to the TV; the mouse and the keyboard talk to the computer. Process/Storage The cable box deciphers which channel you want to watch; the CPU translates your instructions (via software) to the hardware. Output Computers are not really as complicated as they initially seem. You just have to learn the basic functions of the various parts, and then you can separate them into three categories:  Input Any device that lets you talk to the computer (such as a mouse or keyboard).  Process/Storage Main functions of a computer, which happen inside the computer case. Not surprisingly, the Central Processing Unit (CPU) does all the processing; the storage function is handled by any number of drives (hard, floppy, Zip, tape-backup, CD/DVD-ROM) or disks (compact discs or floppy diskettes).  Output Any device that lets the computer talk to you (such as a monitor or speakers). If you're having trouble understanding this input/output stuff, think of your home television (TV) set. Televisions and computers are similar in several ways:  The remote control is comparable to the mouse (or any other input device such as a mouse or joystick). A remote control  The cable box (while not nearly as powerful as a computer) is similar to a computer in communicates with a that it can process information (such as deciphering which channel you want to watch) television much like a and, if programmable, store information (such as when to show the film using a built-in mouse communicates timer). with a computer.  The TV displays the channel much like a monitor displays information. 15  There are several different types of computer systems out there. Here's a very brief description of the most common ones… Table 1-2: Types of Computers Computer Description A mainframe is a big, powerful, expensive computer that can support many users at the same time. Large businesses and organizations use mainframes. Capacity: Enormous - the capacity of several hundred or even thousands of PCs Speed: Very fast - much, much faster than a PC Mainframe Cost: Very, very expensive - can usually only be afforded by large organizations Users: Only used by large businesses and organizations A PC is a personal computer, originally designed by IBM way back in 1981. Many different companies make PCs, but all of them are IBM-compatible. What this means, according to Bill Gates, is that they will all run Microsoft Windows. Capacity: Average hard disk size is 20 GB to 80 GB Speed: Fast. Average speed is from 1 GHz to 3 GHz PC Cost: Fairly inexpensive - under $1,000 - and getting cheaper every day! Users: Just about everyone uses a PC! Homes, offices, schools… Developed by Apple, a Macintosh is a computer, but it is NOT a PC. Macs have a different operating system and use their own software and hardware. Capacity: Average hard disk size is 20 GB to 80 GB Speed: Fast. Average speed is from 500 MHz to 2 GHz Cost: Fairly inexpensive, but usually more than an equivalent PC Mac Users: Just about everyone, especially in the education and design fields A network is a group of computers that are connected so that they can share equipment and information. Most people on a network use workstations, which are simply PCs that are connected to the network. A server is a central computer where users on the network can save their files and information. Capacity: (Workstation) Same as a PC, only needs an inexpensive network card (Server) Greater than a PC, often more than 100 GE Speed: (Workstation) Same as a PC Networked (Server) Generally faster than a PC, may use multiple CPUs Computer Cost:(Workstation) Same as a PC (Server) More expensive than a PC but not as costly as a mainframe Users: (Workstation) People in a networked office or organization (Server) Generally a network administrator or engineer A laptop, or notebook, is a lighter and more portable version of a PC or Mac that can run on batteries. Capacity: Average hard disk size is 10 GB to 40 GB Speed: Fast, but slightly less than a PC. Average speed is from 700 MHz to 2 GHz Laptop Cost: Fairly inexpensive, but more than an equivalent PC Users: People on the move, especially business people and students A PDA (Personal Data Assistant) is a handheld computer that is generally used to keep track of appointments and addresses. Capacity: Much smaller than a PC - 8 MB to 64 MB of storage space Speed: Much slower than a PC - 8 MHz to 266 MHz Palmtop/PDA Cost: Expensive when compared to the capacities of a PC Users: Business people and others who need to be organized 16  Lesson 1-3: The Front of a Computer and Peripheral Devices Figure 1-15 The front of a computer case. Scanner Monitor Printer Speakers CD-ROM or System unit DVD player Floppy drive Mouse The system unit or computer case is that plastic box that sits under your monitor or desk and is covered with slots, buttons, and lights. Computer cases come in several shapes and sizes. Older computers often have the horizontal desktop case, which has gradually been replaced by the vertical tower case. Manufacturers are now phasing out the tallest towers because the compact size of the smallest tower, known as a mini-tower, is attractive to consumers. Everything outside of and connected to the system unit is called peripherals. You can add dozens of peripherals and accessories to make it more useful and fun. Common peripherals include printers, scanners, external hard drives, CD-ROM drives, and digital cameras. Many peripherals are considered to be input devices, because they allow you to talk to your computer by inputting information. Other peripherals are output devices, because they let your computer talk back to you. One more thing: all peripherals are considered to be part of a computer’s hardware. Table 1-3: What’s on the Front or Outside of a Computer Case? Item Description System Unit or A plastic or metal case with slots, buttons, and lights in the front and holes Computer Case in the back. This is the most important part of a computer because it contains the Central Processing Unit (CPU). The system unit directs the computer, performs calculations, and stores information. Floppy Drive Reads and writes to 3½-inch floppy disks. A floppy disk can store about 1.5 MB of information—about as much as a novel. 17  Item Description Hard Drive The computer‘s main, long-term storing device. Unlike floppy disks and (Not shown) CD-ROMs, you typically cannot remove a hard disk. CD-ROM or DVD Drive CD-ROMs and DVDs for your computer can store lots of information and look exactly like CDs for your stereo and DVDs for your home DVD player. In fact, you can listen to audio CDs on a CD-ROM drive and even watch DVD movies on a DVD drive. The only real difference between a CD-ROM and a DVD is how much information they can store. A CD-ROM can store at least 700 MB (megabytes) of information, while a DVD can store much more—up to 4.7 GB (gigabytes) or 9.4 GB on a dual-layer DVD. Most CD-ROMs and DVD are read-only, meaning you can‘t write information to them. You can buy special CD-ROM and DVD drives that can write or burn information to special CD-R, CD-RW, DVD-R, and DVD- RW discs. Zip Drive A special type of disk drive that can read and write to Zip disks. A Zip disk (Not shown) is a lot like a floppy disk, although they are faster and can store more information—from 100 to 250MB (megabytes). Tape Backup A device that you can use to store backups, or copies, of the information (Not shown) on a computer‘s hard drive. Keyboard The keyboard is the thing you type on to tell your computer what to do. Input Devices Mouse Like the keyboard, the mouse is another input device that you use to communicate with your computer. Scanner Scanners work like photocopiers, except the image is translated into a digital image in your computer rather than copied onto paper. Monitor The monitor resembles a television set, and is where the computer Output Devices displays information. Speakers If visible, your computer speakers are similar to those on a stereo system (or at least a cheap stereo system). They allow your computer to play sounds. Printer A printer is where a computer writes down information or output, onto paper, or a hardcopy. 18  Lesson 1-4: The Inside of a Computer Power supply Central Processing Unit (CPU) ROM-BIOS Figure 1-16 The side view of the guts CD-ROM or of a tower case DVD-ROM drive Floppy disk Ports drive Hard disk drive (HDD) Expansion cards Expansion slots Motherboard Figure 1-6 Random-access memory (RAM) Now that you know what’s on the outside, let’s crank open that mysterious computer case and look inside. But no tools required—we’ve done all the work for you. Just compare Figure 1-6 with Table 1-4: What’s Inside a Computer Case? to see what’s important. Everything plugs into a Table 1-4: What’s Inside a Computer Case? computer’s Item Description motherboard. Motherboard The main piece of circuitry in a computer. Everything connects to or is wired to the motherboard. Central Processing The computer‘s brain or heart, the CPU is a computer‘s main chip. The CPU Unit (CPU) is really nothing more than an incredibly fast and powerful calculator. Random Access A computer‘s temporary storage place, where it gets its work done. For Memory (RAM) example, when you use a word processor to type a letter, the letter is stored in the computer‘s memory. ROM-BIOS A computer‘s ROM-BIOS (stands for Read Only Memory – Basic Input/Output System) is a special chip with instructions for the computer to communicate with other hardware parts. Expansion Slot An expansion slot lets you add more features and capabilities to a computer by plugging in expansion cards. 19  Item Description Expansion Card A card that allows you to expand your computer‘s capabilities, such as a modem card, a network card, a video card, or a sound card. PCMCIA Cards Notebook computers are too small to use expansion cards, so they use special credit-card sized PCMCIA cards instead. You plug in a PCMCIA card, or PC Card, into a notebook computer to give it more features and capabilities. Nobody‘s getting tested on this, but PCMCIA stands for Personal Computer Memory Card International Association. Lesson 1-5: The Back of a Computer (Ports) Figure 1-17 On/Off switch The back of a computer case. Keyboard port Mouse port USB ports Ethernet connector Serial port (COM1) Parallel port (printer) Line-out jack Serial port (speakers/headphone) (COM2) Line-in jack Joystick port Microphone jack Phone jack Wall jack Video (monitor) Expansion spaces When you look at the back of a computer, you may feel a bit overwhelmed by all the slots and holes. Fortunately, manufacturers have added some fairly standard icons and color coding to help you identify what should be plugged into your computer and where. Before long, you’ll recognize those icons and colors, and the configuration won’t seem so mysterious. It’s rather like hooking up cable and a DVD player to the back of your television—unless you’re one of those people who just wait for the cable guy to take care of that heinous task. In any case, this lesson will review each item piece by piece so you won’t get completely lost. You may feel a bit Before we begin, let’s define a couple of terms. The first thing you’ll notice is that the back of overwhelmed the first your computer has lots of holes. Those holes are called (depending on who you ask) jacks, time you look at the ports, or connectors. You may notice that some of the connectors have holes, but some have back of a computer. what look like stickpins (which are aptly named pins). The ones that have holes are called female connectors; the ones that have pins are called male connectors. Let’s leave it at that. 20 Table 1-5: Port Icon Description What’s on the The keyboard and mouse jacks look identical on most Back of a PCs, so look for colors and icons to help you with Computer plugging in these devices. Case? Keyboard & Mouse Some mice and keyboards use USB ports. Older mice may use a serial port. Serial (or COM) ports are a very versatile type of port. Some of the things you can plug into a serial port include: Serial or COM a mouse, modem, scanner, or digital camera. Most computers have two serial ports: COM1 and COM2. You plug your printer into the parallel, or printer, port. Parallel or Printer Many newer printers may use a USB port. Designed to replace older Serial and Parallel ports, the USB (Universal Serial Bus) can connect computers with a number of devices, such as printers, keyboards, mice, scanners, digital cameras, PDAs, and more. Better yet, the USB port supports plug-and-play, so you can simply plug in a USB device and start using it. USB USB 1 ports can transfer information at a speed up to 12 Mbps (Megabytes per Second). Newer USB 2 ports can transfer information at a speed up to 480 Mbps. Most computers come with two USB ports. You plug your monitor into the video port. Video or Monitor Plug in your speakers or headphone into the Line Out Line Out / jack. The Line In jack allows you to listen to your computer Line In using a stereo system. You can plug a microphone into this jack to record sounds on your computer. Microphone If you have a joystick, musical (MIDI) keyboard, or other Joystick or Game gaming device, this is where you plug it in. The phone or modem jack is where you plug your computer into a phone line. Phone or Modem You can connect your computer to a network by plugging Network or Ethernet in an Ethernet cable in this port. An SCSI port is one of the fastest ways to connect a hard SCSI drive, CD-ROM drive, or other device to a computer. A FireWire (IEEE 1394 or i.LINK) port lets you connect such devices as hard disks and digital camcorders to a Firewire computer. A FireWire port can transfer information at a speed up to 400 Mbps (Megabytes per Second). 21  Lesson 1-6: System Bus and Expansion Cards Figure 1-18 Expansion cards plug directly into a computer‘s motherboard. Figure 1-19 Most computers have around six expansion slots. Expansion slots Highway System Bus  The number of lanes determines  The bus width determines how how many cars can use the much information can flow highway at once along the bus at a time  The speed limit determines how  The bus speed determines fast cars can drive on the how fast information can travel highway You’re furious! You just bought an expensive digital camcorder only to find out that it can’t connect to your computer because your computer apparently doesn’t have a Firewire port. Don’t worry—you can easily add a Firewire port to the computer by buying an expansion card. Expansion cards allow you to add more gizmos and capabilities to a computer. You can also use expansion cards to replace a component of a computer that breaks, like a modem. Expansion cards plug into expansion slots on a computer’s motherboard. A computer talks to its expansion cards—and everything else on the motherboard—through its bus. A computer’s bus is an electronic pathway that carries information between devices in Expansion cards plug a computer. Two factors determine how information flows through the bus: the bus width and directly into the the bus speed. motherboard.  Bus Width The bus width determines how many ―lanes‖ there are on a computer’s electronic highway. Actually, the bus width isn’t measured in lanes, but in bits. The wider the bus, the more information can travel across it at the same time.  Bus Speed The bus speed determines how fast information can travel through the bus. The higher the bus speed, the faster information can travel through it. Bus speed is measured in MHz. 22  As if this weren’t confusing enough there are several bus types out there. They include:  ISA The Industry Standard Architecture (ISA) is the original, slowest, and oldest type of bus. The ISA bus has a width of 16 bits and a speed of 8 MHz. The ISA bus is going the way of dinosaurs and is no longer found on new computers.  PCI The Peripheral Component Interconnect (PCI) bus is the main bus found in computers. The PCI bus can have a width of 32 or 64 bits. The PCI bus supports Plug and Play, which lets you add new devices to a computer without a complicated installation process. PCI Express is the next generation of PCI. PCI Express uses PIC programming concepts and communications standards, but is based on a much faster serial communications system.  AGP An Accelerated Graphics Port (AGP) is a blazingly fast bus that is currently only used for video cards. The AGP port has a width of 64 bits and supports Plug and Play. So what kind of expansion cards are out there? Here are some of the more common expansion cards that you may come across… Table 1-6: Common Types of Expansion Cards Expansion Card Description A modem allows computers to exchange information through ordinary telephone lines. Almost all computers already come with built-in modems, so Modem you would probably only want to add a modem expansion card if the original modem in a computer breaks. A network interface card (NIC) is an expansion card that connects a computer to other computers on a network. Network A video card or adapter is what generates the images and text displayed on a monitor. Computers come with a built-in video card, but some people like to upgrade their original video card with faster, more powerful video cards. Video or Graphics A sound card lets a computer play and record sounds, just like a home stereo system. Sound You can use expansion cards to add additional ports to a computer, such as the newer Firewire or USB 2 ports. Additional Port(s) 23  Lesson 1-7: Memory Cache Figure 1-10 An illustration of how a RAM Hard Disk computer searches for Cache Cache information in a memory cache. 1. The computer looks 2. When the computer 3. If the computer 4. If the computer still for data in the does not find what Figure 1-11 internal cache first. it‘s looking for in can‘t find what it can‘t find what it This is the fastest the internal cache, An illustration of how a way the computer it next looks in the needs in the needs, it looks at police officer looks for a can get information. external cache. internal or external the slow as gun in a ―weapons cache.‖ Figure 1-10 1. Hopefully the officer 2. If the officer can‘t 3. If the officer can‘t 4. If the officer still has his revolver in find his revolver in his hand, ready for his hand, he next find his revolver in can‘t find his action. reaches down to its holster, he next revolver, his last his holster for the Figure 1-11 gun. runs back to see if stop is a gun store. he left it in the A memory cache increases a computer’s performance by storing the most recently used data. There are two types of cache:  Internal Cache (also called primary or L1 cache) When the computer needs data it first looks in the internal cache. The internal cache is inside the CPU and is the fastest possible way for the computer to get information. The internal cache can normally only contain a very small amount of information.  External Cache (also called secondary or L2 cache) If the computer doesn’t find the data in the internal cache, it then looks in the external cache. The external cache is slower than the internal cache, but much faster than the normal RAM memory. The external cache normally holds much more information than the internal cache, but still not as much as the main memory (RAM). 24  Lesson 1-8: Computer Performance Figure 1-12 There are lots of factors that determine a computer‘s speed. Most of them are listed in Table 1-7: Factors that Affect Computer Performance. Wondering why your neighbor’s computer is so much faster than your computer? There are a number of reasons why a computer may run faster or slower. You learn about each of them by reading Table 1-7: Factors that Affect Computer Performance. A much simpler reason that your neighbor’s computer is faster than your computer is probably because it’s newer. Table 1-7: Factors that Affect Computer Performance Factor Description Arguably the single most important factor that determines a computer‘s performance is the speed of its CPU. The speed of the CPU is measured in megahertz (MHz) and gigahertz (GHz). The faster the CPU, the faster the CPU Speed computer. The first PC in 1981 ran at 4.77 MHz, while today‘s computers can run at speeds exceeding 3,000 MHz, or 3 GHz. The amount of RAM, or memory, is another very important factor in a computer‘s performance. Generally, the more RAM a computer has the better its performance. However, you usually won‘t see much of an improvement Amount of RAM after 1 GB of RAM. Video cards have their own processor and memory, just like the computer does. The faster the processor and the more memory a video card has, the faster it can draw images on the monitor. Video card performance is especially Type of Video Card important if you‘re interested in playing newer, 3D computer games. 25  Factor Description A hard drive‘s average access time is how fast it can find information. Average access time is measured in milliseconds (ms), or 1/1000 of a second. The lower the access speed, the faster the hard drive. Most newer computers have an average access time of 8 to 15 ms. Another factor that determines hard drive performance is how fast it spins, in Hard Drive Speed revolutions per minute (rpms). Faster IDE hard drives may have speeds as fast as 7,200 rpm, while high-end SCSI hard drives have speeds of 15,000 rpm. Not only do you need a fast hard drive, you have to make sure that is has plenty of free storage space. Microsoft Windows uses this hard disk space to create a cache on the hard drive where it stores temporary information. Free Hard Disk Space Normally a computer stores a file in the same location on a hard drive. Over time, a hard drive can become fragmented, and instead of storing a file in the same location it begins storing parts of it all over. When the computer needs to read a fragmented file, it must read several different parts of the hard drive Hard Disk instead of just one. Defragmenting a hard drive puts the fragmented files back Fragmentation together in one place. You should defragment your computer‘s hard drive about once a month. Microsoft Windows can multitask, or run more than one program or task at a time—probably no different than your job. And, just like your job, the more programs or tasks you throw at Windows, the longer it takes to complete each Multitasking one, and hence a drop in computer performance. Considerations Lesson 1-9: Buying a Desktop Computer Figure 1-13 What should you look for when you‘re buying a new computer? That depends on what you want it to do. Table 1-8: Desktop Computer Buyer’s Guide lists some of the more important factors and features to be aware of when buying a new computer. Just make sure the information listed isn‘t too out of date! 26  Nothing’s worse than going to the computer store and listening to a know-it-all salesperson tell you to buy the most expensive computer in the store because the Radon graphics accelerator with 128 megabytes of RAM is something he thinks you’re definitely going to need. Instead of listening to a nerdy computer salesperson, who may be on commission or a sales quota, call one of your computer-geek friends or relatives, tell them how you’re going to use your computer, and ask what they would recommend. If a computer-geek friend isn’t readily available, Table 1-8: Desktop Computer Buyer’s Guide will give you a good idea of what you should look for when you buy a new computer. Just remember that computer technology changes about as quickly as the latest fashions (every six months), so this information will probably be out of date shortly after you read it. Table 1-8: Desktop Computer Buyer’s Guide Factor Budget Middle of the Road High End, Gaming Duron or Celeron at Pentium 4 at 2GHz, Pentium 4 at 3GHz, 2GHz Athlon at 1.7 GHz Athlon at 2.1GHz CPU 256MB 512MB 1GB RAM 15-inch or 17-inch CRT 17-inch CRT or 19-inch CRT or 15-inch flat panel/LCD 17-inch flat panel/LCD Monitor 27  Factor Budget Middle of the Road High End, Gaming 32MB 64MB to 128MB 128MB or more Video Memory 40GB to 60GB 80GB 120GB or more Hard Drive CD-ROM Drive CD-RW Drive DVD+-R/RW & CD-R/RW Drive CD or DVD Drive USB 1.0 USB 2.0 USB 2.0, Firewire Ports Ethernet, 56K modem Ethernet, 56K modem Included Devices Lesson 1-10: Buying a Notebook Computer Figure 1-14 What should you look for when you‘re buying a new computer? That depends on what you want it to do. Table 1-9: Notebook Buyer’s Guide lists some of the more important factors and features to be aware of when buying a new computer. Just make sure the information listed isn‘t too out of date! Deciding on which notebook to buy is even more confusing than buying a desktop computer. That’s because there is much more variance in features and prices between various notebooks. Notebook computers can’t be upgraded as easily as desktop computers, so your decision is 28 pretty much final. Table 1-9: Notebook Buyer’s Guide will give you a good idea of what you should look for when you buy a new notebook computer. Just remember that notebook technology changes incredibly fast, so don’t use Table 1-9: Notebook Buyer’s Guide after December 2003. Some other important factors to consider when buying a notebook include:  Size Generally speaking, while convenient and cool looking, smaller notebooks aren’t as powerful or fast as larger notebook computers. If you travel frequently and need to lug your notebook around with you, you might want to consider a smaller notebook. If your notebook doesn’t move around much you’re probably better off with a larger notebook.  Battery Life A notebook’s battery life can range any where from 2 to 7 hours. Some notebooks can even accept a second battery for extra long life. Battery life probably isn’t much of an issue if you only use your notebook when it’s plugged into the wall.  Warrantee Notebook computers are notorious for breaking down. What’s worse, they’re not very easy to open and they have their own unique notebook parts, so they’re much harder and more expensive to repair than their desktop counterparts. Most of us hate the old three- year extended warrantee sales pitch, but if you’re buying a notebook computer the cost of the extra warranty is probably worth it. 29   Included Devices and Features Notebook computers usually have several devices and gizmos built-in—often more than a desktop computer! A modem and Ethernet port are usually a standard part of most notebooks today. Some notebooks also have memory card readers (especially useful if you have a digital camera or PDA), Firewire ports, and even wireless networking, known as WiFi. If you’re comparing various notebook models, make sure that you know what devices are or aren’t included. Table 1-9: Notebook Buyer’s Guide Factor Budget Middle of the Road High End Duron, Celeron, Duron, Celeron, Pentium 4 at 2GHz or Pentium 3 , or Athlon at Pentium 3 or 4, or better CPU 700MHz or better Athlon at 1GHz or better 256MB 256MB 512MB RAM 16MB 32MB to 64MB 32MB to 64MB Video Memory 20GB 30GB 60GB Hard Drive CD-ROM Drive CD-RW Drive DVD & CD-R/RW Drive CD or DVD Drive USB 1.0 USB 2.0 USB 2.0, Firewire Ports 56K modem Ethernet, possibly WiFi Ethernet, WiFi (wireless (wireless networking) networking), 56K 56K modem modem, Bluetooth (a next-generation wireless port) Included Devices 30  Lesson 1-11: Upgrading a Computer Figure 1-15 Computer upgrades can get expensive! There‘s a fine line between when it‘s more cost effective to upgrade an older computer, or to simply buy a new computer altogether. Figure 1-16 Most computer upgrades require that you, or better yet someone who actually knows about computers, opens up the computer case. When you upgrade a computer, you usually replace older components with newer components to improve the computer’s performance. You can also upgrade a computer by adding additional components, such as more memory or a second hard drive. Upgrading a computer to improve its performance is often cheaper than buying a new computer. For most upgrades you will need someone with a lot of computer experience to do the upgrade for you. It’s often difficult to determine which is better—upgrading an old computer or simply buying a new computer. If you’re an average computer user, plan on buying a new computer every four or five years (sorry—someone has to break this news to you). By then, the cost of a new computer will be less expensive than any effective upgrades you do. So what can you do to upgrade a computer? The following table lists some of the more common upgrades. 31 Table 1-10: Typical Things to Upgrade on a Computer Upgrade Description Increasing the amount of memory in a computer is probably the most effective and inexpensive upgrades you can make. More memory can significantly increase the performance of your computer. 512MB to 1GB of memory is all you Memory (RAM) should ever need—for the next year or so anyway. The hard drives in newer computers have become so huge that you may never need to buy another one. If you do somehow run out of room on your hard drive, you can buy a second one, since most computer can handle two internal hard drives. Hard Disk It‘s often better to buy a whole new computer than to upgrade the CPU and CPU and motherboard. That way you get all new components all once—which is a lot Motherboard cheaper than buying them all individually. There are an endless variety of devices that you can add to a computer. You can add CD-ROM, DVD, and Zip drives, graphics cards, tape backups, and more. Add Devices and Peripherals 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54  Chapter Two: Understanding Hardware Chapter Objectives:  Prerequisites  A desire to learn about  Understand what a CPU does computers.  Learn how memory is measured  Learn about input devices: mouse, keyboard, and digital cameras  Learn about output devices: monitor, graphics, and printers  isLearn Hardware about part any physical storage devices: of a computer thathard drives, you can see or CD-ROMs, and monitor, CD- touch. A computer’s ROM or DVD DVDsdrive, mouse, keyboard, and printer are all different types of hardware. This chapter takes a closer look at the physical parts that constitute a computer. This chapter is broken up into several sections, since there are several different categories of hardware devices. First we’ll examine processing devices, such as computer’s CPU and memory. You’ll finally understand what those technical sounding words megahertz and gigabyte mean. From there we’ll move on to input devices, such as the keyboard and mouse and output devices, such as the monitor and printer. The last part of this chapter discusses storage devices, such as hard drives and CD-ROM drives. That’s a lot of material to cover, so let’s get started! 55 56 57 58 59 60 61 62 63  Execution of more than one instruction through different processors 64 65 66  A detailed Definition of the Microprocessor The microprocessor is a programmable device that takes in numbers, performs on them arithmetic or logical operations according to the program stored in memory and then produces other numbers as a result. Lets expand each of the underlined words: – Programmable device: The microprocessor can perform different sets of operations on the data it receives depending on the sequence of instructions supplied in the given program. By changing the program, the microprocessor manipulates the data in different ways. – Instructions: Each microprocessor is designed to execute a specific group of operations. This group of operations is called an instruction set. This instruction set defines what the microprocessor can and cannot do. – Takes in: The data that the microprocessor manipulates must come from somewhere. It comes from what is called “input devices”. These are devices that bring data into the system from the outside world. These represent devices such as a keyboard, a mouse, switches, and the like. 67 – Numbers: The microprocessor has a very narrow view on life. It only understands binary numbers. A binary digit is called a bit (which comes from binary digit). The microprocessor recognizes and processes a group of bits together. This group of bits is called a “word”. The number of bits in a Microprocessor’s word, is a measure of its “abilities”. – Words, Bytes, etc. The earliest microprocessor (the Intel 8088 and Motorola’s 6800) recognized 8-bit words. – They processed information 8-bits at a time. That’s why they are called “8-bit processors”. They can handle large numbers, but in order to process these numbers, they broke them into 8-bit pieces and processed each group of 8-bits separately. Later microprocessors (8086 and 68000) were designed with 16-bit words. – A group of 8-bits were referred to as a “half-word” or “byte”. 68 – A group of 4 bits is called a “nibble”. – Also, 32 bit groups were given the name “long word”. Today, all processors manipulate at least 32 bits at a time and there exists microprocessors that can process 64, 80, 128 bits Arithmetic and Logic Operations: Every microprocessor has arithmetic operations such as add and subtract as part of its instruction set. – Most microprocessors will have operations such as multiply and divide. – Some of the newer ones will have complex operations such as square root. In addition, microprocessors have logic operations as well. Such as AND, OR, XOR, shift left, shift right, etc. Again, the number and types of operations define the microprocessor’s instruction set and depends on the specific microprocessor. 69 – Stored in memory : First, what is memory? – Memory is the location where information is kept while not in current use. – Memory is a collection of storage devices. Usually, each storage device holds one bit. Also, in most kinds of memory, these storage devices are grouped into groups of 8. These 8 storage locations can only be accessed together. So, one can only read or write in terms of bytes to and form memory. – Memory is usually measured by the number of bytes it can hold. It is measured in Kilos, Megas and lately Gigas. A Kilo in computer language is 2 10 =1024. So, a KB (KiloByte) is 1024 bytes. Mega is 1024 Kilos and Giga is 1024 Mega. When a program is entered into a computer, it is stored in memory. Then as the microprocessor starts to execute the instructions, it brings the instructions from memory one at a time. Memory is also used to hold the data. – The microprocessor reads (brings in) the data from memory when it needs it and writes (stores) the results into memory when it is done. – Produces: For the user to see the result of the execution of the program, the results 70  must be presented in a human readable form. The results must be presented on an output device. This can be the monitor, a paper from the printer, a simple LED or many other forms. A Microprocessor-based system From the above description, we can draw the following block diagram to represent a microprocessor-based system: Input Output Memory 71  Inside The Microprocessor Internally, the microprocessor is made up of 3 main units. – The Arithmetic/Logic Unit (ALU) – The Control Unit. – An array of registers for holding data while it is being manipulated. Organization of a microprocessor- based system Let’s expand the picture a bit. ALU Register I/O Array Input / Output Control System Bus Memory ROM RAM 72  Lesson 2-1: Central Processing Unit (CPU) Figure 2-1 The Intel Pentium 4 is the fastest and most recent CPU available. Figure 2-2 The CPU can get hot! Most CPUs have a built-in fan to keep them from Central burning out. Processing Unit (CPU) Inside the computer case, hidden amongst all the wiring and gizmos, is a particularly important part of the computer known as the central processing unit (or CPU, for short). The CPU is also known as the computer chip (because that’s what it is) or the microprocessor (or processor, for short). Some say the CPU is the brain of the computer while others describe it as the heart. In any case, it’s the thing that makes your computer a computer. The CPU does all the work: It calculates, it processes, it keeps things running smoothly. You might think of it as a talented stage manager. A CPU’s speed is When it does its behind-the-scenes job well, you don’t notice it; you simply enjoy the measured in performance. megahertz (MHz) or Originally, CPUs were given wildly inventive names like Chip. Okay, maybe not. The names gigahertz (GHz). were actually based on numbers like 8088. The next few names in the series—the 286, the 386, and the 486—were actually just shortened names for 80286, 80386, and 80486. Then, what would have been the 586 was dubbed the Pentium. After that, the names became rather mysterious: Pentium Pro and Pentium MMX. Finally, the names returned to a semi-ordered numbering system (albeit a mix of Roman and Arabic numerals): Pentium 2, Pentium 3, and Pentium 4. And that’s where we are at the moment. Both the Pentium 3 and the Pentium 4 are