Protect Your PC from Viruses with the McAfee VirusScan! ©2004 SupraSite(tm) all rights reserved.		Welcome to SuprasiteTM Computers & Networks Introduction History Fundamentals Information Environment Digital Technology LAN Networks Other Computer Fundamentals Description ·         Objectives ·         Software ·         Hardware ·         Peripherals ·         Memory Description In this chapter you'll learn about... ·         What is the point of computers in the first place ·         The various components that make up a computer system: Software, Hardware, Peripherals, and Memory ·         How these components are used to help automate office procedures This chapter will give you a broad background on computers - what they are and how they work. Description Why do we use computers in the first place? Because they do things for us. ·         They are relatively easy to use ·         They don't take breaks, vacations, or sick days ·         They work evenings and weekends ·         They're quick and proficient ·         And once programmed correctly, they don't make mistakes Voice Over Computers make excellent assistants! Description {Diagram: Green screen with "OK" blinking} But a computer needs 'programming' to do these things. In the beginning, without an operating system - all the first computers could say was 'OK.' Then they could work on the fly using 'BASIC' computer language, but nothing could be saved without an operating system. So a computer needs software. Software is instructions or programs that enable a computer to perform any task. With programming, each step has to be thought out to the last detail, but once they're done they can be repeated ad infinitum, without mistakes or deviations that humans introduce. Voice Over But they need instructions or 'software' to get them going. Description While humans multitask (perform multiple instructions at the same time), computer programming performs one task at a time in a certain sequence. Let's look at an example of this... Imagine you and a friend are seated having a discussion. The friend asks you for a glass of water. You would ·         Sit up straight ·         Stand up ·         Find a glass ·         Turn on water ·         Turn off water ·         Give your friend the glass of water ·         And all the while you would continue your discussion - still listening and talking to your friend. While a human can walk and talk and perform actions at the same time, a computer can't do both... The computer toggles back and forth between various activities at such an accelerated speed that it gives the appearance of them happening all at the same time. Description There are two main types of software used by all systems. They are as follows: Operating System ·         The “master control” program that supervises all other programs that run on a computer. This type of software may be abbreviated as OS as in DOS (Disk Operating System). Application Software ·         A computer program designed to perform a specific task. Voice Over Operating systems help the computer 'operate' at a basic level. Applications help you use the computer for specific jobs. Description Managing Files on Disk FAT Table {Diagram: FAT concept} Before we move on to where software and files are stored, let's talk about how those files are stored and managed. Every computer has a method for keeping data and instructions organized - like the filing system in your office cabinets. As information is stored on the system it is given a specific place or address on the hard drive. This method is known as the FAT or File Allocation Table. It acts like a table of contents or index for the computer, keeping track of where directory structure and folders are as well as what 'clusters' or physical spaces on the computer disk are used to store which files. RAM (Random Access Memory) is the agent that accesses the files from the FAT and delivers them to their destination. We'll learn more about clusters and RAM when we get to computer hardware, but first let's talk more about managing files. Description Managing Files on Disk {Diagram: silverware lined up in a drawer} As you use a computer and files are saved and erased from the disk, the information stored for a single file can end up scattered across the disk. Think of it like having a complete set of silverware but after a dinner party - the forks and knives are scattered across the table. You have to collect the silverware and put them back in the drawer where they are organized so that you can easily retrieve them next time you throw a party! Once in a while a fork gets thrown out in the trash - this would be like a broken chain. In the case of a computer file, that file with a broken chain may or may not be salvageable. Description Managing Files on Disk - Utilities There are three important utilities (software tools) available within Windows that help to manage files on disk. 1) Scan Disk: Checks for broken chains or files that have been broken up and separated across a disk and need to be reconnected. 2) Disk Defrag: Allows you to go in and re-organize files in a more compact manner. Disk Defrag connects the element within a 'chain' and ties files back together across disk. 3) Format C: Takes all of the magnetic particles on disk and points them all in the same direction. It is a fairly destructive process used only when initially formatting a disk into partitions or in emergencies for unrecoverable viruses. Description Software needs machinery on which to run. That machinery is called hardware. Hardware is any physical part of the computer including the electronics, case, keyboard and monitor and other 'peripheral' accessories. Let's  look at what's inside a computer... <Click NEXT sets off the following in the Diagram> {Animate: zoom into and reveal inside of box} Voice Over The physical pieces that make up a computer are called hardware. Description Motherboard This is the motherboard. It is the main circuit board and everything is connected to it. It's also called a 'BUS.' The motherboard includes a set of wires or conductors that hook everything together and carry signals between parts of a computer system or between parts of a network. It may be helpful to think of it as a highway where the bits of information go flying around within the computer. The main CPU chip sits on the motherboard. <Click NEXT sets off the following in the diagram> {Animate: CPU highlights and zoom into it } Voice Over The motherboard is the most important piece of hardware. It is the heart of the computer. Central Processing Unit (CPU) The CPU or Central Processing Unit, which sits on the motherboard, is the main computer chip that interprets and executes instructions. It may also be referred to as the processor or microprocessor. When you think of CPU, remember 2 words. It is the BRAINS of operation and it is where SPEED comes from. Click on different parts to see what they do... <Click on any part of the CPU and a pop-up box listed on 0312 appears> ·         BIU: ·         Code Cache: ·         Data Cache: ·         Branch Predictor Unit: ·         Instruction Prefetch Buffer and Decode Unit : ·         Floating Point Unit: ·         Execution Unit and ALU: After you are done exploring Click next to learn about the Hard Drive. Voice Over The CPU sits on the motherboard and is the brains of the system. Description BIU: ·         The Bus Interface Unit (BIU) is the doorway in and out of the whole CPU. It sends code instructions and data from the computer along two different paths, one to the code cache and one to the data cache. Code Cache: ·         Cache is a 'holding pen' for information. Code Cache holds as many instructions as can fit at the same time. Data Cache: ·         Cache is a 'holding pen' for information. Data Cache loads as much data as can fit at the same time that code/instructions will work off of. Branch Predictor Unit: ·         While instructions are waiting in the Code Cache, the Branch Predictor Unit decides how the next steps in programming should be treated. It 'predicts' whether instructions need to travel down the same path and where they will go to get processed. Instruction Prefetch Buffer and Decode Unit : ·         The Instruction Prefetch Buffer retrieves or 'fetches' code from the Branch Predictor Unit and translates or 'decodes' it so that the ALU can understand it. Floating Point Unit: ·         Performs calculations on 'floating point' numbers (such as decimal fractions) that need special processing. Execution Unit and ALU: ·         Within the Execution Unit are the ALUs or Arithmetic Logic Units where actual processing 'arithmetic' goes on. The ALU makes decisions about where instructions or information are sent, i.e. from RAM to the hard drive or from CDROM to memory, etc. Before Pentiums there was one ALU per CPU. Pentiums have 2 ALUs and Pentium IIs and beyond have more. As computers become more sophisticated, the need to direct traffic increases exponentially. Back in the 1940s, the ENIAC ran 70 instructions per second. Now computers are approaching a billion instructions per second. Description Hard Disk The hard disk is a permanent storage device which stores information. The hard disk is literally a hard metal circular plate that stores information magnetically. Voice Over The hard disk is where files are stored. Description Hard Disk {Animation: Hard disk flies out of computer - all else disappears and concentric circles are highlighted} The hard disk is a metal plate divided up like a pizza into sectors and concentric circles called tracks. The tracks are read from the outside in. The point where a track and sector meet is called a cluster. Files are written as chains across the disk. A Read/Write head floats over tracks and reads the information there. Description Hard Disk {Animation: Magnetic particles are highlighted and shift from 1 to 0 positions} Information stored on the disk is made of '1' and '0' bits represented by magnetic particles arranged one way or another. As the read/write head passes over the disk, it sees either a 1 or a 0 by the way the magnetic pole of a particle is pointed (positive or negative). The concept of bits will be explained further in this chapter under "Memory". Description Floppy Disk {Diagram: Interior of computer - floppy drive is highlighted - all else is grayed out.} A floppy disk is a storage device (usually temporary) which stores information. A 'floppy' is literally a thin soft plastic plate that stores information magnetically. Voice Over Floppies allow you to store files outside of the computer. Description Floppy Disk Like all other computer technology, floppy disks have evolved and shrunk from early computer days... {Diagram: floppy}                {Diagram: floppy}                {Diagram: floppy}                {Diagram: floppy}                10" and 12"                           5"                                            3.5"                                         3.5" 2.88 MB early IBM                              360 kb single side 1.44 MB common                available, not common Because a floppy disk is fragile and easily damaged when exposed, a slider protects the disk over the read/write area. Description Random Access Memory (RAM) { Diagram: Interior of computer - RAM is highlighted - all else is grayed out.} As you will learn in the next memory section, information needs to be converted to 1s and 0s so that it can be acted upon by the processor. So programs and data are sent from the hard disk to a place where they can be converted and worked with. Random Access Memory (RAM) is the electronic memory of a computer which is used to temporarily hold programs and information. As we learned about the FAT (File Allocation Table), all files have address and RAM is like the post office retrieving and delivering programs and data to and from the CPU. Information in RAM is erased as soon as the power is turned off. Voice Over RAM allows the computer space to think and work out problems. Description Random Access Memory (RAM) {Diagram: SIMM chip} There are two types of RAM chips placed on the motherboard. ·         SIMM: Single Inline Memory Modules ·         DIMM: Dual Inline Memory Modules, which have electronics on the reverse side as well...   And just an F.Y.I.... NEVER call the hard drive - memory, and NEVER call memory - storage. Voice Over Remember that the hard drive is NOT memory...  and that memory is NOT storage. Navigation Bar Options Home Help Terms Quiz Feedback Quit Menu Previous Summary Next 0000 0003 1300 1400 email Exit 0300 0318 0399 0320 0320 Chapter Title Computer Fundamentals Screen Title Hardware Screen Shot Description CDROM {Diagram: Interior of computer - CDROM drive is highlighted - all else is grayed out.} CDROM is short for Compact Disc - Read Only Memory. A CDROM is another medium for information storage. It is not magnetic like hard and floppy disks; it is optical. Voice Over CDROMs are another storage medium. Description CDROM {Animation: CDROM flies out of computer - all else disappears and spiral and sectors are highlighted} A CDROM is written in a giant spiral starting in middle and tracking out (opposite of a phonograph) and is divided into sectors (more like clusters). Description CDROM {Animation: CDROM turns to side so bumps and pits may be highlighted} Instead of rearranging magnetic particles on a disk one way or another, bumps (land) representing 1s and holes (pits) representing 0s are burned into a plastic disc.  A laser scans over this surface. Description Peripheral {Diagram Whole computer system} {Animate: peripherals popping up} A peripheral is any piece of hardware attached to the computer. It may refer to items attached to the outside of a computer such as a ·         Printer ·         Scanner ·         External modem Voice Over Peripherals are all the 'extras' that you hook up to your computer. Description Peripheral {Diagram: Interior of computer} {Animate: Peripherals popping up} ...Or peripherals may be additional boards put in expansion slots on the motherboard (or bus), such as a ·         NIC (Network Interface Card) ·         Video accelerator ·         SCSII board for scanner ·         Sound card ·         Internal modem Voice Over First we'll look at how external peripherals are connected to a computer Description Ports In order to connect external devices to a computer, the device needs to be connected to a 'port' in the computer. Standard ports are: ·         VGA - monitor ·         Keyboard ·         Mouse ·         Parallel port - printers (like the Ricoh AFICIO 450!) scanners, zip drive ·         Serial port - modem Other types of ports include game ports and the USB port. For now, let's look at the differences between Serial and Parallel ports. Voice Over External peripherals get connected to the computer through a port. Description Ports The basic difference between parallel and serial ports is how they send information. {Diagram: both ports side by side} Serial Port                                                                   Parallel Port Sends data one bit at a time in series.                                               Sends data down the wire side by side. <Link to 0327>                                                                                      <Link to 0328>                                                                 Click on a port to learn more. Description Ports The basic difference between parallel and serial ports is how they send information. {Diagram: both ports side by side} Serial Port <HIGHLIGHTED>                                  Parallel Port Sends data one bit at a time in series.                                               Sends data down the wire side by side.                                                                                                                 <Link to 0328>                                                                 Click on a port to learn more. {Diagram: cable} A standard Serial Port is also known as RS232C specification and consists of a 9 pin shell female on the computer port end and a 25 pin male on the peripheral end. {Diagram: Series of 1s and 0s} With a Serial Port, 1s and 0s go down the line one at a time 'serially' - one after another. The maximum distance for connecting one of these cables is 50 feet, but more than 25 feet is not recommended. Description Ports The basic difference between parallel and serial ports is how they send information. {Diagram: both ports side by side} Serial Port                                                                   Parallel Port <HIGHLIGHTED> Sends data one bit at a time in series.                                               Sends data down the wire side by side. <Link to 0327>                                                                                                                                                      Click on a port to learn more.                                                                                                                 {Diagram: cable} A standard Parallel Port is also known as a "Centronics" cable.  It has a 25 pin on the computer end and a 36 slot connector on the other end with clips. {Diagram: Parallel 1s and 0s} A parallel port sends information in a single direction. It transmits 8 bits (a byte) through 8 wires at a time or 8 times faster. The maximum distance for connecting these cables is up to 25 feet, but more than 15 feet is not recommended. And for scanners, the cable should be no more than 6 feet. There is also an IEEE (International Electrical and Electronics Engineers) 1284 compliant parallel cable with 16 wires allowing bi-directional signal flow with 8 wires going each direction. This is a better grade of cable with better shielding used on Ricoh products. Description Expansion Cards {Diagram: Interior of computer with expansion cards highlighted} In order to connect peripherals a special 'card' that helps the computer 'expand' its capabilities is sometimes required. Different motherboards require different types of cards. The two most commonly accepted are the 8 bit bus and later the 16 bit bus. Cards made for older 8 bit slots have backwards compatibility and can fit into 16 bit slots. Description Expansion Cards and the Motherboard {Diagram: Interior of computer with expansion slots highlighted} Additional functionality has been introduced to motherboard/peripheral connectivity since Industry Standard Architecture (ISA) in 1981. Intel introduced EISA (Extended Industry Standard Architecture) in 1988, but it wasn't accepted due to its expense. In 1992, the local bus was created and enabled faster processing by hooking up wires more directly to the main processor. One of these local buses was the VISA (Video Industry Standard Architecture) bus which added an extra slot for video information. And later, the PCI (Peripheral Component Interconnect/interface) bus allowed more devices to be hooked up and offered more flexibility by running  32 bits at a faster clock speed. So now, most new motherboards are a combination of PCI and ISA. The more recent development is the USB (Universal Serial Bus) port. This port works like a SCSII board and allows peripherals to be daisy-chained together: i.e., the mouse plugs into the keyboard, the keyboard plugs into the computer, etc. It fits into a normal expansion slot, yet functions like a little 'network hub.' Voice Over Industry Standard Architecture or ISA was introduced in 1981 and is still used today. Description Other Peripherals {Diagram: whole computer system with peripherals and modem, scanner and printer highlighted} A modem used to be an optional peripheral, but with the widespread acceptance of the Internet in everyday business, a modem is now a standard device. A modem is a common communication device that allows computers to send information to each other over telephone lines. MODEM stands for  MODulated/DEModulated referring to the audible signals that transmit the information. The audible 'snow' or static is really the sound of 1s and 0s going up and down in frequency and is called 'frequency shift keying.' A scanner is a piece of hardware that translates what it “sees” into a picture format that the computer can use. And a printer, of course, outputs on paper what has been created on the screen of your computer. Other Sound Frequency shift keying static. Description So we have talked about memory and bits of information flying around inside your computer. But just how does memory 'operate?'  It is all done with electronic mathematics! Computers deal with 2 things, and 2 things only, and they are 1s and 0s, otherwise known as binary code. Voice Over Computers deal with 2 things, and 2 things only, and they are 1s and 0s, otherwise known as binary code. Description Bits and Bytes A bit is like a light switch - it can be turned on or off - it can be a 1 or a 0. Bit (b) = 1 or 0 A Byte is one character of information made up of eight bits. Byte (B) = 8 bits = 1 character Think of it as a row of 8 light switches. --- As an aside, the term bit mapping came from the word bit, and refers to a matrix of pixels which in early bitmaps were originally either on (black) or off (white). Voice Over A 1 or 0 bit is the most fundamental element in computer code. Description Additional terms to know are: Kilobyte (KB) = 1,024 bytes Megabyte (MB) = approx. 1 million bytes Gigabyte (GB) = approx. 1 billion bytes Terabyte (TB) = approx. 1 trillion bytes   Since computers all revolve around this system, let's take a closer look at Binary Code. Description To understand how this system works, let's go back to high school Algebra. Remember something called the 'BASE TEN numbering system?' It's a fancy name for how we express numbers in our everyday lives.  We use 10 different symbols (0,1,2,3,4,5,6,7,8,9) to express any given number and put them in specific columns to express how much they represent. 107 106 105 104 103 102 101 100 10,000,000 1,000,000 100,000 10,000 1,000 100 10 1 When we say the number 2975, it means 2 thousands, 9 hundreds, 7 tens, and 5 ones. Voice Over We use Base 10 numbering in our everyday lives Description Computers use something called 'BASE TWO numbering system.' It uses only 2 different symbols to express any given number. It also puts those numbers in specific columns to express how much they represent. 27 26 25 24 23 22 21 20 128 64 32 16 8 4 2 1 A lineup of 8 symbols or bits in a row is a byte. And in this one byte, 256 combinations are possible. Voice Over Computers use a Base 2  or 'Binary' numbering system. Description To express the number 273 in base two or binary code, the computer performs the following calculations: 219-128= 91                                                                           so 128 is on 91-64= 27                                                                               so 64 is on you can't subtract 32 from 27                                           so 32 is off 27- 16=11                                                                               so 16 is on 11- 8=3                                                                                   so 8 is on you can't subtract 4 from 3                                               so 4 is off 3-2=1                                                                                      so 2 is on 1-1=0                                                                                      so 1 is on This may be better understood in the following chart: 27 26 25 24 23 22 21 20 128 64 32 16 8 4 2 1 1 1 0 1 1 0 1 1 So the number 273 is expressed as 11011011 in binary code. Description Binary Code Exercise Try to put the number '192' in binary code 27 26 25 24 23 22 21 20 128 64 32 16 8 4 2 1 <Input> <Input> <Input> <Input> <Input> <Input> <Input> <Input> Description Exercise: Response The number 192 is expressed as 11000000 in binary code. 27 26 25 24 23 22 21 20 128 64 32 16 8 4 2 1 <Input> <Input> <Input> <Input> <Input> <Input> <Input> <Input> 1 1 0 0 0 0 0 0 How did you do? Description Now let's look at how characters are represented as numbers. The computer requires at least: ·         52 different combinations to represent the alphabet - upper and lower case ·         10 combinations for numbers ·         Roughly 30 combinations for special characters The most common way to represent these characters is called ASCII (American Standard Code for Information Interchange). There is an ASCII lookup table for every character set. In addition, certain IBM mainframes used EBCDIC (Extended Binary Coded Decimal Interchange Code), but we will focus on ASCII, because it is the most common character set. Voice Over All the characters in the alphabet can be expressed in Binary Code. Description {Diagram: ASCII chart} ASCII code represents up to 128 different discrete characters. Above is what an ASCII code chart looks like. Voice Over ASCII is a code that all computers understand. Description ASCII to Binary Code Exercise If K in the lookup table equals the number 75, how would you express K in binary code? 27 26 25 24 23 22 21 20 128 64 32 16 8 4 2 1 <Input> <Input> <Input> <Input> <Input> <Input> <Input> <Input> Description Exercise response: K is represented as 01001011 in binary code. 27 26 25 24 23 22 21 20 128 64 32 16 8 4 2 1 <Input> <Input> <Input> <Input> <Input> <Input> <Input> <Input> 0 1 0 0 1 0 1 1 How did you do? Description Motherboard Clock Speed {Diagram: Clock speed} {Animate: gate opening and closing} Binary code is transmitted through transistors on the motherboard. Transistors have gates that allow electrical current to flow through at a certain pulse rate. How fast or slow a computer works or how fast or slow the transistors can send a 1 or 0 through is called the motherboard clock speed. Clock speed is measured in megahertz or millions of ticks per second. Description Motherboard Clock Speed Imagine that the transistors are set up like freeway lanes that allow binary code traffic to flow through them. The clock speed regulates the speed limit across those lanes. So, if you have 8 lanes of traffic running at 8 MHz speed limit, it means 8 lanes times 8 million instructions per second which equals 64 Mb per second. As you increase the lanes of traffic, you increase the speed at which the computer can perform calculations. 16 lanes running at 8 MHz speed limit means 16 lanes times 8 million instructions per second which equals 128 Mb per second. 16 lanes running at 33 MHz speed limit means 16 lanes times roughly 32.5 million instructions per second  which equals 520 Mb per second. Description Personal computers and workstations are used in modern offices to: ·         Originate ·         Assemble ·         Modify ·         Edit ·         Distribute Business Information formats: ·         Text ·         Graphic ·         Numerical ·         Multimedia (Imaging, Video, Audio) Most of which will ultimately result in the production and distribution of paper hard copy. Voice Over Now you should have a basic understanding about how computers are put together. ? ?
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