Chapter 4: File Management, Virus Protection, and Backup

Chapter 2: Computer Hardware 1111Chapter 4: File Management, Virus Protection, and Backup

1Chapter 1: Computer, Internet, Web, and E-Mail Basics

Chapter 2: Computer Hardware 2

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

Chapter 2 Preview


After this chapter, you should be able to:– Explain the factors that might help a

shopper decide whether to purchase a CRT, LCD, or plasma monitor

– Compare and contrast the technologies and applications for printers

– Describe computer’s expansion bus

– Explain hardware compatibility considerations

Chapter 2 Preview


Chapter 2 Outline

• Section A– Data Representation and Digital

Electronics

• Section B– Microprocessors and Memory

• Section C– Storage Devices

• Section D– Input and Output Devices

Computer Concepts 8th EditionParsons/Oja

Chapter 2Computer Hardware

Section A: Data Representation and Digital Electronics


• Data representation makes it possible to convert letters, sounds, and images into a form computers can use for processing

• A digital device works with discrete data, such as the digits 1 and 0

• An analog device works with continuous data

Data Representation: How do computers represent data digitally?

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• Computers are digital

• Just as a standard light switch is a simpler technology than a dimmer, so is digital when compared to analog

Data Representation: How do computers represent data digitally?

digital analog

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• The binary number system (base 2) uses only two digits 0, and 1

• The following table lists some decimal numbers and their binary equivalent:

How does a computer represent numbers?

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• Character data is composed of letters, symbols, and numerals that are not used in arithmetic operations

• ASCII requires only 7 bits for each character

• Extended ASCII uses 8 bits to represent each character

How can a computer represent words and letters using bits?

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• EBCDIC is an alternative 8-bit used by older IBM systems

• Unicode uses 16 bits and provides codes for 65,000 characters – Used for foreign language support

How can a computer represent words and letters using bits?

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• 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

How does a computer convert sounds and pictures into codes?

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• A bit is one binary digit (b)– 0

• A byte is 8 bits (B)– 0010 0100

Quantifying Bits and Bytes: How can I tell the difference between bits and bytes?

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• 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

Quantifying Bits and Bytes: How can I tell the difference between bits and bytes?

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How does a computer store and transport all these bits?

• Bits take the form of electrical pulses that can travel over circuits

• This is almost the same way as electricity flows over a wire when you turn on a light switch

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• Desktop units are designed with expectation that the home user may add or update the equipment

• Small desktop and notebook computers are not designed for users to access all areas

What’s inside the system unit?

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What’s inside the system unit?

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• Most electronic components inside a computer are integrated circuits– Thin slices of silicon crystal packed with

microscopic circuit elements

What’s a computer chip?

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• Semiconducting materials are used to fabricate a chip

• Types of chips:– DIPs– DIMMs– PGAs– SEC cartridge


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• The system board houses all essential chips and provides connecting circuitry between them

How do chips fit together to make a computer?

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How do chips fit together to make a computer?

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Section B: Microprocessors and Memory


• An integrated circuit designed to process instructions– CPU on a chip

Microprocessor Basics:What exactly is a microprocessor?

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• 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

How does a microprocessor work?

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• Technically yes, but most computer owners rarely do

• Reasons not to upgrade– Cost– Technical factors – speed

• Do research before you upgrade your microprocessor

Can I replace my computer’s microprocessor with a faster one?

Page 71


• A temporary holding area for data, application program instructions, and the operating system– As you type, characters are held in RAM

Random Access Memory: What is RAM?

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• 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

How much RAM does my computer need?

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• 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)

Do all computers use the same type of RAM?

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• Type of memory circuitry that holds the computer’s startup routine

• Permanent and non-volatile

• Only way to change the instructions on a ROM chip is to replace the chip

Read-Only Memory: How is ROM different from RAM?

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• A computer needs a semi-permanent way of keeping boot data

• 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 system board

CMOS Memory: Where does a computer store its basic hardware settings?

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Where does a computer store its basic hardware settings?

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How do I get the best computer for my money?

• Different buyers have different needs

• Assess your budget and think about how you plan to use your computer

• Look at ads and visit online computer stores

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Section C: Storage Devices


• A storage medium is the disk, tape, CD, DVD, paper or other substance that contains data

• A storage device is the mechanical apparatus that records and retrieves data from a storage medium

Storage Basics: What are the basic components of a data storage system?

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• 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

How does magnetic storage work?

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How does magnetic storage work?

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• Stores data as microscopic light spots (lands) and dark spots (pits) on the disk surface

• Less susceptible to environmental damage than data recorded on magnetic media

How does optical storage work?

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How does optical storage work?

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How does solid state storage work?• Stores data in a non-volatile, erasable, low-

power chip

• Some solid state storage requires a device called a card reader to transfer data to or from a computer

• Provides faster access to data than magnetic or optical storage technology because it includes no moving parts

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• Devices can be added into empty drive bays

Can I add storage devices to my computer?

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• 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

What is floppy disk technology?

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• HD DS 3½” diskettes have capacity of 1.44 MB

• Zip disks come in 100 MB, 250 MB, and 750 MB versions

How much data can a HD DS disk and a Zip disk hold?

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• Major advantage – portability• Major disadvantage – not a particularly

speedy device and limited storage capacity

• Slowly being replaced by solid state technology

• Today most software vendors use CD-ROM or DVD-ROM disks instead

What are the advantages and disadvantages of HD DS floppy disks?

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• Disk density - closeness and size of magnetic particles on the disk’s surface

• Zip disks store data at a higher density than a standard 3½” floppy disk

How can ZIP disks store more data than standard floppy disk?

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• Hard disk platter - a flat, rigid disk made of aluminum or glass and coated with magnetic iron oxide particles– Density far exceeds floppy disk

• Hard disk - one or more platters and their associated read-write heads– Preferred type of main storage

• Miniature hard drives store 20 to 40 GB

How does a hard disk work?

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How does a hard disk work?

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• 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

What’s the downside of hard disk storage?

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• Tape backup - copy of data on hard disk stored on magnetic tape

• Relatively inexpensive

• Primarily used on business computers

• Not suitable for everyday storage tasks

• Sequential-access storage medium

Tape Storage: What’s the purpose of a tape drive?

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• CD– Holds up to 80 minutes of music or 700

MB of data

• DVD– Holds about 4.7 GB of data– A double layer DVD has two recordable

layers on the same side and can store 8.5 GB of data

CD and DVD technology: Is there a difference between CD and DVD technology?

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How do CD and DVD drives work?

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• 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

How do CD and DVD drives work?

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Can I use a single drive to work with any CD or DVD media?

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• It is slower than hard disk access

• Not yet a suitable replacement

Are rewritable CD or DVD drives an acceptable replacement for a hard disk?

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• Not exactly– Movie files are still very large– Television DVD drives include MPEG

decoding circuitry

Is my computer DVD drive the same as the one connected to my TV?

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• Portable, provides fast access to data and uses very little power– USB flash drive– CompactFlash card– MMC– SecureDigital– SmartMedia

Solid State Storage: When would I use solid state storage?

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Section D: Input and Output Devices


Basic Input Devices: What devices can I use to get data into a computer?

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• CRT (cathode ray tube)

• LCD (liquid crystal display) – LCDs are clearer, have low radiation

emission, are portable, and compact– LCDs are also more expensive than CRTs

What are my options for display devices?

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What are my options for display devices?

• Plasma screen technology– Lightweight, compact, and more expensive

than CRT monitors

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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

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• A laser printer paints 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

How do laser printers compare to ink jet printers?

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How do laser printers compare to ink jet printers?

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• 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

What is a dot matrix printer?

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What is a dot matrix printer?

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• 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

What other printer technologies are available?

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• Resolution– Measured in dpi (dots per inch)

• 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

Printers: What features should I look for in a printer?

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• 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

What features should I look for in a printer?

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• Duplex capability– A printer with duplex capability can print on both

sides of the paper

• Memory– A computer sends data for a printout to the

printer along with a set of instructions on how to print the data

What features should I look for in a printer?

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• Internal devices– Tools required

• Screwdriver• Directions

– Before installing• Unplug the computer• Ground yourself

– Installing• Follow the directions

Installing Peripheral Devices: Is it difficult to install a new peripheral device?

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• Expansion slot - long, narrow socket on the system board into which you can plug an expansion card

• Expansion card - small circuit board that provides computer with ability to control storage, input or output device

What’s an expansion slot?

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• 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

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• Equipped with a special type of external slot called a PCMCIA slot

• Typically a notebook only has one slot, but the slot can hold more than one PC card (PCMCIA expansion cards)

Do notebook computers contain expansion slots?

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• Used to connect a peripheral device

• Expansion port - any connector that passes data in and out of a computer or peripheral device

What is an expansion port?

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What is an expansion port?

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How do I know which cable to use? Serial

DB-9

ParallelDB-25M

USB

SCSIC-50F

IEEE 13394

VGAHDB-15

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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

Conclusion

Chapter 4: File Management, Virus Protection, and Backup

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