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

Computer Concepts 5th Edition Parsons/Oja Page 57 Chapter 2 Chapter 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 Edition Parsons/Oja Page 58 Section A Chapter 2 Data 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 Edition Parsons/Oja Page 61 Section A Chapter 2 Data 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 Edition Parsons/Oja Page 62 Section A Chapter 2 Computer Hardware Under the hood….

Computer Concepts 5th Edition Parsons/Oja Page 63 Section A Chapter 2  The motherboard houses all essential chips and provides connecting circuitry between them

Computer Concepts 5th Edition Parsons/Oja Page 70 Section B Chapter 2 Microprocessors 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 Edition Parsons/Oja Page 70 Section B Chapter 2 Microprocessors 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  Less capacity than most storage devices  Access time: nanoseconds  Big impact on performance of system

Computer Concepts 5th Edition Parsons/Oja Page 71 Section B Chapter 2 Microprocessors 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 Edition Parsons/Oja Page 67 Section B Chapter 2 Microprocessors and Memory CPU  Gets data and instructions from RAM  Processes data  Sends results to RAM

Computer Concepts 5th Edition Parsons/Oja Page 67 Section B Chapter 2 Microprocessors 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 Edition Parsons/Oja Page Section B Chapter 2 Microprocessors 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 Edition Parsons/Oja Page 72 Section B Chapter 2 Microprocessors 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 Edition Parsons/Oja Page 72 Section B Chapter 2 Microprocessors 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 Edition Parsons/Oja Page 76 Section C Chapter 2 Storage 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 Edition Parsons/Oja Page 77 Section C Chapter 2 Storage 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 Edition Parsons/Oja Page 77 Section C Chapter 2 Storage 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 Edition Parsons/Oja Page 78 Section C Chapter 2 Storage 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 Edition Parsons/Oja Page 79 Section C Chapter 2 Storage 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 Edition Parsons/Oja Page 80 Section C Chapter 2 Storage 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 Edition Parsons/Oja Page Section C Chapter 2 Storage 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 Edition Parsons/Oja Page 81 Section C Chapter 2 Storage 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 Edition Parsons/Oja Page 81 Section C Chapter 2 Storage 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

Computer Concepts 5th Edition Parsons/Oja Page 83 Section C Chapter 2 Storage 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 Edition Parsons/Oja Page 83 Section C Chapter 2 Storage 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 Edition Parsons/Oja Page 84 Section C Chapter 2 Storage 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 Edition Parsons/Oja Page 85 Section C Chapter 2 Storage 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

Computer Concepts 5th Edition Parsons/Oja Page 85 Section C Chapter 2 Storage 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 Edition Parsons/Oja Page 86 Section C Chapter 2 Storage 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

Computer Concepts 5th Edition Parsons/Oja Page 87 Section C Chapter 2 Storage 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 Edition Parsons/Oja Page 87 Section C Chapter 2 Storage 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 Edition Parsons/Oja Page 88 Section D Chapter 2 Input 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 Edition Parsons/Oja Page 92 Section D Chapter 2 Input 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 Edition Parsons/Oja Page 93 Section D Chapter 2 Input 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 Edition Parsons/Oja Page 94 Section D Chapter 2 Input 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 Edition Parsons/Oja Page 94 Section D Chapter 2 Input 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

Computer Concepts 5th Edition Parsons/Oja Page Section D Chapter 2 Input 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 Edition Parsons/Oja Page 95 Section D Chapter 2 Input 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 Edition Parsons/Oja Page 95 Section D Chapter 2 Input 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 Edition Parsons/Oja Page 96 Section D Chapter 2 Input and Output Devices 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