Computer Concepts 5th Edition Parsons/Oja Page 58 CHAPTER 2 Data Representation and Digital Electronics Section A PARSONS/OJA Computer Hardware

Computer Concepts 5th EditionParsons/Oja

Page 58

CHAPTER

2

Data Representation and Digital Electronics

Section A

PARSONS/OJA

Computer Hardware


Page 57

Chapter

2Chapter PREVIEW

Computer Hardware

When you complete this chapter, you should be able to: Explain why most computers are digital Describe the role of the ALU List factors that affect CPU performance Explain RAM and ROM Compare storage technologies Describe computer’s expansion bus Explain hardware compatibility considerations Compare and contrast technologies for

peripherals


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Section AChapter

2Data Representation and Digital Electronics

A computer uses a bit (binary digit) as the building block for more complex data representations

By grouping bits together, computers create sequences that represent numbers, letters, pictures, music, and more

Why are computers digital?


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Section AChapter

2Data Representation and Digital Electronics

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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Section AChapter

2Computer Hardware

Under the hood….


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Section AChapter

2

The motherboard houses all essential chips and provides connecting circuitry between them


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Section BChapter

2Microprocessors and Memory

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

Random Access Memory: What is RAM?


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Section BChapter


Why is RAM so important?

Blackboard: constantly creating info then erasing Volatile: requires power to hold data Capacity

Holds data to be processed Holds instructions Holds results until stored Less capacity than most storage devices

Access time: nanoseconds Big impact on performance of system


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Section BChapter


Virtual Memory

Operating system uses portion of hard drive as extension of RAM

Can handle programs which require more RAM Slows performance


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Section BChapter


CPU

Gets data and instructions from RAM Processes data Sends results to RAM


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Section BChapter


CPU

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.


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Section BChapter


Microprocessor Performance Factors: What makes one microprocessor perform better than another?

CPU speed is influenced by several factors: Clock speed – Megahertz, Gigahertz

• Heart beat: how fast can instructions be executed

Cache memory: for frequently used data• Improves CPU performance


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Section BChapter


Read-Only Memory: How does the CPU restart when it can’t store instructions in RAM?

ROM (read-only memory): chips containing instructions ROM is permanent and non-volatile Since RAM is empty when a computer is turned on, ROM

BIOS is used ROM BIOS (basic input/output system) is a set of

instructions that tells computer how to access the disk drives and peripheral devices

Once operating system is loaded, the computer can understand your input, run software and access your data


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Section BChapter


Boot up process:

Power up: power light is on Start boot program: execute instructions in ROM Power-On Self-Test: checks monitor, RAM,

keyboard, disk drives Load operating system into RAM:

Will look in a: drive if it contains disk Check configuration and setup files Ready


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Section CChapter

2Storage Devices

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

A storage device, such as a floppy disk drive, a hard drive, zip drive, and a CD-ROM drive, is used to store the data

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


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Section CChapter

2Storage Devices

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

What’s the difference between magnetic and optical storage technologies?


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Section CChapter

2Storage Devices


Data stored on magnetic media such as floppy disks can be altered by dust, smoke, heat, and mechanical problems.

And magnetic fields… Some experts estimate that the reliable life span

of data stored on magnetic media is about three years


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Section CChapter

2Storage Devices

Optical storage stores data as microscopic light spots (lands) and dark spots (pits) on the disk surface

Data stored on an optical storage device is less susceptible to environmental damage



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Section CChapter

2Storage Devices

Where is the data actually stored on 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

What happens if the metal slide cover is bent?


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Section CChapter

2Storage Devices

What’s the capacity of a floppy disk?

3 ½ diskettes have capacity of 1.44 MB Other floppy disk types

ZIP disks – 100 MB and 250 MB

ZIP disk

Superdisk


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Section CChapter

2Storage Devices

Major advantage – portability

Major disadvantages – Slow Limited capacity You will lose them

What are the advantages and disadvantages of floppy disk technology?


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Section CChapter

2Storage Devices

Can I protect the data on a floppy disk?

The write-protect window allows you to protect data by making it read-only when it is open, but to modify the storage data, it must be closed


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Section CChapter

2Storage Devices

Hard Disk Technology: advantages of hard disk drives

It provides lots of storage capacity It provides faster access to files than floppy disk

drives It is economical


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Section CChapter

2Storage Devices

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


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Section CChapter

2Storage Devices

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

Requires sequential access Inconvenient and slow Data is arranged as essentially a long sequence

of bits that begin at one end of the tape and stretches to the other

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


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Section CChapter

2Storage Devices

CD technology: Why would I want a CD-ROM drive in addition to a hard disk drive?

CD-ROM stands for Compact Disc Read-Only Memory data stamped on when manufactured coated with clear plastic, durable estimated life exceeds 500 years inexpensive to manufacture ideal for distribution of large files


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Section CChapter

2Storage Devices

What’s the capacity and speed of a CD?

A single CD-ROM holds up to 650 MB Equals 500 floppies Three to four zip disks

It is very durable


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Section CChapter

2Storage Devices

Can I create my own CDs?

CD-R stands for compact disc-recordable allows you to create your own CDs by

recording on a CD-R disk Speed

Recording is done on a CD-R drive uses a laser to change the reflectivity of a dye

layer on a blank CD-R disk Can be read by standard CD-ROM or DVD drive


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Section CChapter

2Storage Devices

DVD Technology: How is DVD different from CD technology?

DVD (digital video disc or digital versatile disc) variation of CD technology designed to provide enough storage capacity for a full

length movie will replace video tape (experts believe)

DVD-ROM disk (sometimes used for DVD-Video) stamped with data when manufactured cannot change or add data stores 4.7 GB

• Thousands of floppy disks• Eight CD-ROM

ideal for games, maps, large databases


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Section CChapter

2Storage Devices

Are CDs and DVDs interchangeable?

CD-ROM drives can not play DVDs DVDs can play CD-ROM, most CD-R and most

CD-RW disks


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Section CChapter

2Storage Devices

Is there a DVD equivalent to CD-RW?

DVD+RW uses phase change technology cannot be used on DVD-RAM

DVD-RAM uses a blend of technologies to record data cannot be used on DVD+RW

Both DVD+RW and DVD-RAM can be read on DVD-ROM drives

There is also DVD-R


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Section DChapter

2Input and Output Devices

Expansion slots, cards and ports: How does a computer get data from RAM to a peripheral device?

Data Bus carries data from one component to another For example, RAM to CPU


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Section DChapter


Why do some peripheral devices include a disk or CD?

Some devices require software, called a device driver

The device driver sets up communication between your computer and the device

Today’s PCs include Plug and Play (PnP) that automatically takes care of these technical details


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Section DChapter


Which display device produces the best image?

Screen size is the measurement in inches from one corner of the screen diagonally across to the opposite corner.

Dot pitch - a measure of image clarity smaller dot pitch means a crisper image

Resolution - number of pixels a monitor can display


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Section DChapter


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.

Color capability come in color or black and white


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Section DChapter


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


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Section DChapter


What features should I look for in a printer?

Printer cost printers for microcomputers range from $100 to $5000 duty cycle - indication of the number of pages a printer

can be expected to print per month Per-copy cost

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

Warranty cover mechanical problems


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Section DChapter


What’s the difference between an ink jet printer and a solid ink printer?

An ink jet printer is today’s most popular printing technology. print head consists of a series of nozzles that

sprays ink onto paper What happens if it rains???


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Section DChapter


Is a laser better than an ink jet?

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


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Section DChapter


Why would anyone want a dot matrix printer?

Dot matrix printers produce characters and graphics using impact Cheap, cheap low quality output can print multipart carbon forms

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Computer Concepts 5th Edition Parsons/Oja Page 58 CHAPTER 2 Data Representation and Digital Electronics Section A PARSONS/OJA Computer Hardware