Computer Concepts 7 t h E d i t i o n Chapter 2: Computer Hardware 1

Chapter 2 Computer Hardware Section A: Data Representation and Digital Electronics Computer Concepts 7th Edition Parsons/Oja

Chapter Preview After this chapter, you should be able to: Explain why most computers are digital Describe the role of the ALU List factors that affect performance Explain RAM Compare storage technologies Describe computer’s expansion bus Explain hardware compatibility considerations Chapter 2: Computer Hardware 3

Data Representation: How do computers represent data digitally? Data representation makes it possible to convert letters, sounds, and images into electrical signals Digital electronics makes it possible for computer to manipulate simple “on” and “off” signals to perform complex tasks A digital device works with discrete data or digits, such as 1 and 0 An analog device works with continuous data such as sound waves Chapter 2: Computer Hardware 4

Data Representation: How do computers represent data digitally? Computers are digital primarily because digital technology is simple, dependable, and adaptable Just as a standard light switch is a simpler technology than a dimmer, so is digital when compared to analog Chapter 2: Computer Hardware 5

How can a computer represent numbers? Unlike the decimal system, the binary number system (base 2) uses only two digits 0, and 1 The following table lists some decimal numbers and their binary equivalent: Chapter 2: Computer Hardware 6

How can a computer represent words and letters using bits? Character data is composed of letters, symbols, and numerals that will not be used in arithmetic operations ASCII (American Standard Code for Information Interchange) requires only 7 bits for each character Extended ASCII uses eight bits for each character Chapter 2: Computer Hardware 7

How can a computer represent words and letters using bits? EBCDIC (Extended Binary-Coded Decimal Interchange Code) is an alternative 8-bit used by older IBM systems Unicode uses 16 bits and provides codes for 65,000 characters – a bonus for representing alphabets of multiple languages Used for foreign language support Chapter 2: Computer Hardware 8

How does a computer convert sounds and pictures into codes? Sounds and pictures must be transformed into a format the computer can understand A computer must digitize colors, notes, and instrument sounds into 1s and 0s Chapter 2: Computer Hardware 9

Quantifying Bits and bytes: How can I tell the difference between bits and bytes? A bit is one binary digit (b) A byte is 8 bits (B) 0010 0100 A nibble is 4 bits 0011 Chapter 2: Computer Hardware 10

Quantifying Bits and bytes: How can I tell the difference between bits and bytes? Kilo- means a 1000, Mega- means million, Giga -means billion Kilobit (Kb) is 1,024 bits Kilobyte (KB) is 1, 024 bytes Megabyte (MB) is 1,048,576 bytes Gigabyte (GB) is 1,073,741,824 bytes Chapter 2: Computer Hardware 11

Does a typical computer owner need to mess around inside the system unit? Desktop units are designed with expectation that the home user may add or update the equipment Notebook computers are not designed for users to access all areas. Although users can update certain components Chapter 2: Computer Hardware 12

Does a typical computer owner need to mess around inside the system unit? Chapter 2: Computer Hardware 13

What’s a computer chip? Most electronic components inside a computer are integrated circuits - thin slices of silicon crystal packed with microscopic circuit elements Wires Transistors Capacitors Logic gates Resistors Chapter 2: Computer Hardware 14

What’s a computer chip? Semiconducting materials are used to fabricate a chip Types of chips DIPs DIMMs PGAs SEC cartridge Chapter 2: Computer Hardware 15

What’s a computer chip? Chapter 2: Computer Hardware 16

How do chips fit together to make a computer? The motherboard houses all essential chips and provides connecting circuitry between them Chapter 2: Computer Hardware 17

How do chips fit together to make a computer? Chapter 2: Computer Hardware 18

Chapter 2 Computer Hardware Section B: Microprocessors and Memory Computer Concepts 7th Edition Parsons/Oja

Microprocessor Basics: What exactly is a microprocessor? A microprocessor is an integrated circuit designed to process instructions CPU on a chip Chapter 2: Computer Hardware 20

How does a microprocessor work? The CPU has two parts ALU (arithmetic logic unit) Performs arithmetic operations Performs logical operations Uses registers to hold data being processed The CPU’s control unit directs and coordinates processing Chapter 2: Computer Hardware 21

Can I replace my computer’s microprocessor with a faster one? Technically yes, but most computer owners rarely do Reasons not to upgrade Cost Technical factors – speed Do research before you upgrade your microprocessor Chapter 2: Computer Hardware 22

Random Access Memory: What is RAM? RAM (random access memory) - an area of the computer that temporarily holds data before and after it is processed As you type, characters are held in RAM Chapter 2: Computer Hardware 23

How much RAM does my computer need? RAM is primary storage (main memory) Measured in megabytes (MB) or gigabytes (GB) Today’s computers have between 128 MB and 2 GB of RAM Depends on software you use You can purchase additional RAM A computer can use disk storage to simulate RAM. This is called virtual memory Not as fast as RAM Chapter 2: Computer Hardware 24

Do all computers use the same type of RAM? No. RAM components vary in speed, technology, and configuration Speed is measured in nanoseconds. 1 nanosecond (ns) is 1 billionth of a second It can also be expressed in MHz (millions of cycles per second) SDRAM (Synchronous Dynamic RAM) RDRAM (Rambus Dynamic RAM) Chapter 2: Computer Hardware 25

Read-Only Memory: How is ROM different from RAM? ROM (read-only memory) is one or more chips containing instructions that help a computer prepare to process tasks ROM is permanent and non-volatile Only way to change the instructions on a ROM chip is to replace the chip Chapter 2: Computer Hardware 26

CMOS memory: Where does a computer store its basic hardware settings? A computer needs a semi-permanent way of keeping boot data, such as the number of hard disk sectors and cylinders CMOS memory - holds data but requires very little power to retain its contents Retains important computer settings after you turn the power off Can run by a battery on the motherboard Housed within the same chip carrier as ROM BIOS Chapter 2: Computer Hardware 27

Where does a computer store its basic hardware settings? Chapter 2: Computer Hardware 28

Chapter 2 Computer Hardware Section C: Storage Devices Computer Concepts 7th Edition Parsons/Oja

Storage Basics: What are the basic components of a data storage system? A storage medium is the disk, tape, CD, DVD, paper or other substance that contains data A storage device, such as a floppy disk drive, a hard drive, zip drive, CD drive, and a DVD drive, is used to store the data Chapter 2: Computer Hardware 30

How does magnetic storage work? Magnetic storage - stores data by magnetizing microscopic particles on the disk or tape surface Read-write head - mechanism in the disk drive that reads and writes magnetized particles that represent data Chapter 2: Computer Hardware 31

How does magnetic storage work? Chapter 2: Computer Hardware 32

How does optical storage work? Optical storage stores data as microscopic light spots (lands) and dark spots (pits) on the disk surface Data recorded on optical media is generally considered to be less susceptible to environmental damage than data recorded on magnetic media Chapter 2: Computer Hardware 33

How does optical storage work? Chapter 2: Computer Hardware 34

Can I add storage devices to my computer? Devices can be added into empty drive bays Chapter 2: Computer Hardware 35

Floppy disk Technology: Why is it called a “floppy disk”? A floppy disk is a round piece of flexible mylar plastic covered with a thin layer of magnetic oxide and sealed inside a protective casing Chapter 2: Computer Hardware 36

How much data can a floppy disk hold? 3 ½ diskettes have capacity of 1.44 MB Other floppy disk types ZIP disks – 100 MB, 250 MB, and 750 MB Superdisks – 120 MB or 240 MB Chapter 2: Computer Hardware 37

Disk density - closeness and size of magnetic particles it stores How can ZIP disks and Superdisks store more data than standard floppy disk? Disk density - closeness and size of magnetic particles it stores Zip disks and Superdisks store data at a higher density than a standard 3 ½ floppy disk Chapter 2: Computer Hardware 38

What are the advantages and disadvantages of floppy disk technology? Major advantage – portability Major disadvantage – not a particularly speedy device and limited storage capacity Today most software vendors use CD-ROM or DVD-ROM disks instead Chapter 2: Computer Hardware 39

How does a hard disk work? Hard disk platter - a flat, rigid disk made of aluminum or glass and coated with magnetic oxide Density far exceeds floppy disk Hard disk - one or more platters and their associated read-write heads. Preferred type of main storage Chapter 2: Computer Hardware 40

How does a hard disk work? Chapter 2: Computer Hardware 41

What’s the downside of hard disk storage? Head crash - when a read-write head runs into a dust particle or other contaminant on the disk Head crash damages some data on disk Triggered by jarring the hard disk while in use Not limited to hard disks Chapter 2: Computer Hardware 42

Tape Storage: What’s the purpose of a tape drive? Tape backup - copy of data on hard disk stored on magnetic tape Relatively inexpensive Not suitable for everyday storage tasks Sequential-access storage medium Chapter 2: Computer Hardware 43

CD and DVD technology: Is there a difference between CD and DVD technology? Holds up to 80 minutes of music or 700 MB of data DVD Holds about 4.7 GB of data Upcoming DVD standards will further increase the storage capacity Chapter 2: Computer Hardware 44

How do CD and DVD drives work? Chapter 2: Computer Hardware 45

How do CD and DVD drives work? Recordable technology uses a laser to change the color in a dye layer sandwiched beneath the clear plastic disk surface Rewritable technology uses “phase change” technology to alter a crystal structure on the disk surface Chapter 2: Computer Hardware 46

Can I use a single drive to work with any CD or DVD media? Chapter 2: Computer Hardware 47

Are rewritable CD or DVD drives an replacement for a hard disk? It is slower than hard disk access; therefore not a suitable replacement yet Chapter 2: Computer Hardware 48

Most movie DVDs are encoded in MPEG-2 data coding format Is my computer DVD drive the same as the one connected to my television set? Not exactly. Movie files are still very large. Television DVD drives include MPEG decoding circuitry Most movie DVDs are encoded in MPEG-2 data coding format Chapter 2: Computer Hardware 49

Solid State Storage: When would I use solid state storage? Portable, provides fast access to data and uses very little power Widely used in digital cameras, MP3 music players, notebook computers, PDAs, and cell phones You can use solid state storage as you would a floppy disk USB flash drive CompactFlash card MMC SecureDigital SmartMedia Chapter 2: Computer Hardware 50

Chapter 2 Computer Hardware Section D: Input and Output Devices Computer Concepts 7th Edition Parsons/Oja

Basic Input Devices: What devices can I use to get data into a computer? Chapter 2: Computer Hardware 52

What are my options for display devices? CRT (cathode ray tube) uses gun-like mechanisms to direct beams of electrons toward the screen and activate individual dots of color that form an image LCD (liquid crystal display) produces an image by manipulating light within a layer of crystal cells LCDs are clearer, have low radiation emission, are portable, and compact LCDs are also more expensive than CRTs Chapter 2: Computer Hardware 53

What are my options for display devices? Plasma screen technology creates an on-screen image by illuminating miniature colored fluorescent lights arrayed in a panel-like screen Lightweight, compact, and more expensive than CRT monitors Chapter 2: Computer Hardware 54

How does an ink jet printer work? Nozzle-like print head that sprays ink onto paper to form characters and graphics Most ink jet printers use CMYK color Chapter 2: Computer Hardware 55

How do laser printers compare to ink jet printers? A laser printer uses the same technology as a photocopier to paint dots of light on a light-sensitive drum Higher quality than ink jet More expensive to buy than ink jet Less expensive to operate than ink jet Chapter 2: Computer Hardware 56

Is a laser better than an ink jet? Chapter 2: Computer Hardware 57

What is a dot matrix printer? Dot matrix printers produce characters and graphics by using a grid of fine wires Introduced in 1970s Low quality output Used for “back-office” applications that demand low operating cost and dependability Can print multipart carbon forms Chapter 2: Computer Hardware 58

Why would anyone want a dot matrix printer? Chapter 2: Computer Hardware 59

What other printer technologies are available? Thermal transfer printer Uses page-sized ribbons coated with wax Print head consists of heating elements to melt the wax Dye sublimation printer Similar to wax, but page-sized ribbon contains dye Print heads diffuse the dye Chapter 2: Computer Hardware 60

Printers: What features should I look for in a printer? Resolution Printer resolution is measured in dpi (dots per inch), the number of dots it can print per linear inch Come in color or black and white Chapter 2: Computer Hardware 61

What features should I look for in a printer? Print speed Measured either by pages per minute (ppm) or characters per second (cps) Color takes longer than black and white Text prints faster than graphics Ten pages per minute (black and white) = typical speed for today’s jet and laser printers Chapter 2: Computer Hardware 62

What features should I look for in a printer? Duty cycle - indication of the number of pages a printer can be expected to print per month Indicates maintenance costs Operating costs Printers require ongoing costs including ribbons, ink cartridges, and toner Per copy cost is the cost of printing a page with an average amount of text, graphics, and color Memory A computer sends data for a printout to the printer along with a set of instructions on how to print the data Chapter 2: Computer Hardware 63

Installing Peripheral Devices: Is it difficult to install a new peripheral device? Internal devices Tools required Screwdriver Directions Before installing Unplug the computer Ground yourself Installing Follow the directions Chapter 2: Computer Hardware 64

What is an expansion slot? Expansion slot - long, narrow socket on the motherboard into which you can plug an expansion card Graphics card (for connecting monitor) Modem (for transmitting data over phone or cable lines) Sound card (for connecting speakers) Expansion card - small circuit board that provides computer with ability to control storage, input or output device Most computers have 4 - 8 expansion slots Chapter 2: Computer Hardware 65

What is an expansion slot? Chapter 2: Computer Hardware 66

What are the major types of expansion slots? ISA (Industry Standard Architecture) Used today only for some modems and other relatively slow devices PCI (Peripheral Component Interconnect) Offers fast transfer speeds and a 32-bit or 64-bit data bus AGP (Accelerated Graphics Port) Provides a high-speed data pathway primarily used for graphics cards Chapter 2: Computer Hardware 67

Do notebook computers also contain expansion slots? Most notebook computers are equipped with a special type of external slot called a PCMCIA slot (personal computer memory card international association) Typically a notebook only has one slot, but the slot can hold more than one PC card (PCMCIA expansion cards) Chapter 2: Computer Hardware 68

What is an expansion port? To connect a peripheral device to an expansion card, you plug a cable from the device into the expansion port Expansion port - any connector that passes data in and out of a computer or peripheral device Chapter 2: Computer Hardware 69

What is an expansion port? Chapter 2: Computer Hardware 70

How do I know which port to use? Serial DB-9 Parallel DB-25M USB SCSI C-50F IEEE 13394 VGA HDB-15 Chapter 2: Computer Hardware 71

Conclusion You should now be able to: Explain why most computers are digital Describe the role of the ALU List factors that affect performance Explain RAM Compare storage technologies Describe computer’s expansion bus Explain hardware compatibility considerations Chapter 2: Computer Hardware 72