computer hardware
DESCRIPTION
Data Representation and Digital Electronics. Section A. CHAPTER 2. Computer Hardware. PARSONS/OJA. Page 58. Chapter 2. Computer Hardware. Chapter PREVIEW. When you complete this chapter, you should be able to: Explain why most computers are digital Describe the role of the ALU - PowerPoint PPT PresentationTRANSCRIPT
Computer Concepts 5th EditionParsons/Oja
Page 58
CHAPTER
2
Data Representation and Digital Electronics
Section A
PARSONS/OJA
Computer Hardware
Computer Concepts 5th EditionParsons/Oja
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
Computer Concepts 5th EditionParsons/Oja
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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?
Computer Concepts 5th EditionParsons/Oja
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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?
Computer Concepts 5th EditionParsons/Oja
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Section AChapter
2Computer Hardware
Under the hood….
Computer Concepts 5th EditionParsons/Oja
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Section AChapter
2
The motherboard houses all essential chips and provides connecting circuitry between them
Computer Concepts 5th EditionParsons/Oja
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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?
Computer Concepts 5th EditionParsons/Oja
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Section BChapter
2Microprocessors and Memory
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
Access time: nanoseconds Big impact on performance of system
Computer Concepts 5th EditionParsons/Oja
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Section BChapter
2Microprocessors and Memory
Virtual Memory
Operating system uses portion of hard drive as extension of RAM
Can handle programs which require more RAM Slows performance
Computer Concepts 5th EditionParsons/Oja
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Section BChapter
2Microprocessors and Memory
CPU
Gets data and instructions from RAM Processes data Sends results to RAM
Computer Concepts 5th EditionParsons/Oja
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Section BChapter
2Microprocessors and Memory
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.
Computer Concepts 5th EditionParsons/Oja
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Section BChapter
2Microprocessors and Memory
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
Computer Concepts 5th EditionParsons/Oja
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Section BChapter
2Microprocessors and Memory
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
Computer Concepts 5th EditionParsons/Oja
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Section BChapter
2Microprocessors and Memory
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
Computer Concepts 5th EditionParsons/Oja
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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
Computer Concepts 5th EditionParsons/Oja
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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?
Computer Concepts 5th EditionParsons/Oja
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Section CChapter
2Storage Devices
What’s the difference between magnetic and optical storage technologies?
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
Computer Concepts 5th EditionParsons/Oja
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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
What’s the difference between magnetic and optical storage technologies?
Computer Concepts 5th EditionParsons/Oja
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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?
Computer Concepts 5th EditionParsons/Oja
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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
Computer Concepts 5th EditionParsons/Oja
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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?
Computer Concepts 5th EditionParsons/Oja
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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
Computer Concepts 5th EditionParsons/Oja
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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
Computer Concepts 5th EditionParsons/Oja
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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.
Computer Concepts 5th EditionParsons/Oja
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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
Computer Concepts 5th EditionParsons/Oja
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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
It is very durable
Computer Concepts 5th EditionParsons/Oja
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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
Computer Concepts 5th EditionParsons/Oja
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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 ideal for games, maps, large databases
Computer Concepts 5th EditionParsons/Oja
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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
Computer Concepts 5th EditionParsons/Oja
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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
Computer Concepts 5th EditionParsons/Oja
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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
Computer Concepts 5th EditionParsons/Oja
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Section DChapter
2Input and Output Devices
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
Computer Concepts 5th EditionParsons/Oja
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Section DChapter
2Input and Output Devices
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
Computer Concepts 5th EditionParsons/Oja
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Section DChapter
2Input and Output Devices
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
Computer Concepts 5th EditionParsons/Oja
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Section DChapter
2Input and Output Devices
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
2Input and Output Devices
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
Computer Concepts 5th EditionParsons/Oja
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Section DChapter
2Input and Output Devices
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???
Computer Concepts 5th EditionParsons/Oja
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Section DChapter
2Input and Output Devices
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
Computer Concepts 5th EditionParsons/Oja
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Section DChapter
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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