CHAPTER 2 Section A Data Representation and Digital

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

Chapter 2 Computer Hardware Chapter PREVIEW u 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 5 th Edition Parsons/Oja Page 57

Section A Data Representation and Digital Electronics 2 Chapter Why are computers digital? u A computer uses a bit (binary digit) as the building block for more complex data representations u By grouping bits together, computers create sequences that represent numbers, letters, pictures, music, and more Computer Concepts 5 th Edition Parsons/Oja Page 58

Section A Data Representation and Digital Electronics 2 Chapter How does a computer convert sounds and pictures into codes? u Sounds and pictures must be transformed into a format the computer can understand u A computer must digitize colors, notes, and instrument sounds into 1 s and 0 s Computer Concepts 5 th Edition Parsons/Oja Page 61

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

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

Section B Microprocessors and Memory 2 Chapter Random Access Memory: What is RAM? u 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 Computer Concepts 5 th Edition Parsons/Oja Page 70

Chapter 2 Section B Microprocessors and Memory Why is RAM so important? u Blackboard: constantly creating info then erasing u Volatile: requires power to hold data u Capacity } Holds data to be processed } Holds instructions } Holds results until stored } Less capacity than most storage devices u Access time: nanoseconds u Big impact on performance of system Computer Concepts 5 th Edition Parsons/Oja Page 70

Chapter 2 Section B Microprocessors and Memory Virtual Memory u Operating system uses portion of hard drive as extension of RAM u Can handle programs which require more RAM u Slows performance Computer Concepts 5 th Edition Parsons/Oja Page 71

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

Chapter 2 Section B Microprocessors and Memory CPU u The CPU has two parts u ALU (arithmetic logic unit) } performs arithmetic operations } performs logical operations } uses registers to hold data being processed u The CPU’s control unit directs and coordinates processing. Computer Concepts 5 th Edition Parsons/Oja Page 67

Chapter 2 Section B Microprocessors and Memory Microprocessor Performance Factors: What makes one microprocessor perform better than another? u 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 5 th Edition Parsons/Oja Page 67 -68

Chapter 2 Section B Microprocessors and Memory Read-Only Memory: How does the CPU restart when it can’t store instructions in RAM? u ROM (read-only memory): chips containing instructions u ROM is permanent and non-volatile u Since RAM is empty when a computer is turned on, ROM BIOS is used u ROM BIOS (basic input/output system) is a set of instructions that tells computer how to access the disk drives and peripheral devices u Once operating system is loaded, the computer can understand your input, run software and access your data Computer Concepts 5 th Edition Parsons/Oja Page 72

Chapter 2 Section B Microprocessors and Memory Boot up process: u Power up: power light is on u Start boot program: execute instructions in ROM u Power-On Self-Test: checks monitor, RAM, keyboard, disk drives u Load operating system into RAM: } Will look in a: drive if it contains disk u Check configuration and setup files u Ready Computer Concepts 5 th Edition Parsons/Oja Page 72

Chapter Section C Storage Devices 2 Storage Basics: What are the basic components of a data storage system? u 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 u A storage medium is the disk, tape, CD, DVD, paper or other substance that contains data Computer Concepts 5 th Edition Parsons/Oja Page 76

Section C Storage Devices 2 Chapter What’s the difference between magnetic and optical storage technologies? u Magnetic storage - stores data by magnetizing microscopic particles on the disk or tape surface u Read-write head - mechanism in the disk drive that reads and writes magnetized particles that represent data Computer Concepts 5 th Edition Parsons/Oja Page 77

Chapter Section C Storage Devices 2 What’s the difference between magnetic and optical storage technologies? u Data stored on magnetic media such as floppy disks can be altered by dust, smoke, heat, and mechanical problems. u And magnetic fields… u Some experts estimate that the reliable life span of data stored on magnetic media is about three years Computer Concepts 5 th Edition Parsons/Oja Page 77

Section C Storage Devices 2 Chapter What’s the difference between magnetic and optical storage technologies? u Optical storage stores data as microscopic light spots (lands) and dark spots (pits) on the disk surface u Data stored on an optical storage device is less susceptible to environmental damage Computer Concepts 5 th Edition Parsons/Oja Page 78

Chapter Section C Storage Devices 2 Where is the data actually stored on a floppy disk? u 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 u What happens if the metal slide cover is bent? Computer Concepts 5 th Edition Parsons/Oja Page 79

Section C Storage Devices Chapter 2 What’s the capacity of a floppy disk? u 3 ½ diskettes have capacity of 1. 44 MB u Other floppy disk types } ZIP disks – 100 MB and 250 MB Superdisk ZIP disk Computer Concepts 5 th Edition Parsons/Oja Page 80

Section C Storage Devices 2 Chapter What are the advantages and disadvantages of floppy disk technology? u Major advantage – portability u Major disadvantages – } Slow } Limited capacity } You will lose them Computer Concepts 5 th Edition Parsons/Oja Page 80 -81

Chapter Section C Storage Devices 2 Can I protect the data on a floppy disk? u 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 5 th Edition Parsons/Oja Page 81

Chapter Section C Storage Devices 2 Hard Disk Technology: advantages of hard disk drives u It provides lots of storage capacity u It provides faster access to files than floppy disk drives u It is economical Computer Concepts 5 th Edition Parsons/Oja Page 81

Chapter Section C Storage Devices 2 What’s the downside of hard disk storage? u 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 5 th Edition Parsons/Oja Page 83

Chapter Section C Storage Devices 2 Tape Storage: What’s the purpose of a tape drive? u Requires sequential access u Inconvenient and slow u Data is arranged as essentially a long sequence of bits that begin at one end of the tape and stretches to the other u Tape backup - copy of data on hard disk stored on magnetic tape. Computer Concepts 5 th Edition Parsons/Oja Page 83

Chapter Section C Storage Devices 2 CD technology: Why would I want a CD-ROM drive in addition to a hard disk drive? u 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 5 th Edition Parsons/Oja Page 84

Chapter Section C Storage Devices 2 What’s the capacity and speed of a CD? u A single CD-ROM holds up to 650 MB } Equals 500 floppies } Three to four zip disks u It is very durable Computer Concepts 5 th Edition Parsons/Oja Page 85

Chapter Section C Storage Devices 2 Can I create my own CDs? u CD-R } stands for compact disc-recordable } allows you to create your own CDs by recording on a CD-R disk } Speed u 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 u Can be read by standard CD-ROM or DVD drive Computer Concepts 5 th Edition Parsons/Oja Page 85

Chapter Section C Storage Devices 2 DVD Technology: How is DVD different from CD technology? u 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) u 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 5 th Edition Parsons/Oja Page 86

Chapter Section C Storage Devices 2 Are CDs and DVDs interchangeable? u CD-ROM drives can not play DVDs u DVDs can play CD-ROM, most CD-R and most CD-RW disks Computer Concepts 5 th Edition Parsons/Oja Page 87

Chapter Section C Storage Devices 2 Is there a DVD equivalent to CD-RW? u DVD+RW } uses phase change technology } cannot be used on DVD-RAM u DVD-RAM } uses a blend of technologies to record data } cannot be used on DVD+RW u Both DVD+RW and DVD-RAM can be read on DVD-ROM drives u There is also DVD-R Computer Concepts 5 th Edition Parsons/Oja Page 87

Chapter Section D Input and Output Devices 2 Expansion slots, cards and ports: How does a computer get data from RAM to a peripheral device? u Data Bus carries data from one component to another } For example, RAM to CPU Computer Concepts 5 th Edition Parsons/Oja Page 88

Chapter Section D Input and Output Devices 2 Why do some peripheral devices include a disk or CD? u Some devices require software, called a device driver u The device driver sets up communication between your computer and the device u Today’s PCs include Plug and Play (Pn. P) that automatically takes care of these technical details Computer Concepts 5 th Edition Parsons/Oja Page 92

Chapter Section D Input and Output Devices 2 Which display device produces the best image? u Screen size is the measurement in inches from one corner of the screen diagonally across to the opposite corner. u Dot pitch - a measure of image clarity } smaller dot pitch means a crisper image u Resolution - number of pixels a monitor can display Computer Concepts 5 th Edition Parsons/Oja Page 93

Chapter Section D Input and Output Devices 2 Printers: What features should I look for in a printer? u Resolution } printer resolution is measured in dpi (dots per inch), the number of dots it can print per linear inch. u Color capability } come in color or black and white Computer Concepts 5 th Edition Parsons/Oja Page 94

Chapter Section D Input and Output Devices 2 What features should I look for in a printer? u 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 5 th Edition Parsons/Oja Page 94

Chapter Section D Input and Output Devices 2 What features should I look for in a printer? u 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 u 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 u Warranty } cover mechanical problems Computer Concepts 5 th Edition Parsons/Oja Page 94 -95

Chapter Section D Input and Output Devices 2 What’s the difference between an ink jet printer and a solid ink printer? u An ink jet printer is today’s most popular printing technology. } print head consists of a series of nozzles that sprays ink onto paper u What happens if it rains? ? ? Computer Concepts 5 th Edition Parsons/Oja Page 95

Chapter Section D Input and Output Devices 2 Is a laser better than an ink jet? u A laser printer uses the same technology as a photocopier to paint dots of light on a lightsensitive drum. } higher quality than ink jet } more expensive to buy than ink jet } less expensive to operate than ink jet Computer Concepts 5 th Edition Parsons/Oja Page 95

Chapter Section D Input and Output Devices 2 Why would anyone want a dot matrix printer? u Dot matrix printers produce characters and graphics using impact } Cheap, cheap } low quality output } can print multipart carbon forms Computer Concepts 5 th Edition Parsons/Oja Page 96