Computer Hardware

1. Data Representation and Digital Electronics Section A CHAPTER 2 Computer Hardware PARSONS/OJA Page 58

2. 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 • 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 Page 57

3. Section A Chapter 2 Data Representation and Digital Electronics Why are computers digital? • 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 Page 58

4. Section A Chapter 2 Data Representation and Digital Electronics How does a computer convert sounds and pictures into codes? • 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 Page 61

5. Section A Chapter 2 Computer Hardware Under the hood…. Page 62

6. Section A Chapter 2 • The motherboard houses all essential chips and provides connecting circuitry between them Page 63

7. Section B Chapter 2 Microprocessors and Memory Random Access Memory: What is RAM? • 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 Page 70

8. 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 • Access time: nanoseconds • Big impact on performance of system Page 70

9. 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 Page 71

10. Section B Chapter 2 Microprocessors and Memory CPU • Gets data and instructions from RAM • Processes data • Sends results to RAM Page 67

11. 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 unitdirects and coordinates processing. Page 67

12. 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 Page 67-68

13. 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 Page 72

14. 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 Page 72

15. 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 Page 76

16. Section C Chapter 2 Storage Devices What’s the difference between magnetic and optical storage technologies? • Magneticstorage - stores data by magnetizing microscopic particles on the disk or tape surface • Read-writehead - mechanism in the disk drive that reads and writes magnetized particles that represent data Page 77

17. 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 Page 77

18. Section C Chapter 2 Storage Devices What’s the difference between magnetic and optical storage technologies? • Optical storagestores 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 Page 78

19. 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? Page 79

20. 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 Superdisk ZIP disk Page 80

21. Section C Chapter 2 Storage Devices What are the advantages and disadvantages of floppy disk technology? • Major advantage – portability • Major disadvantages – • Slow • Limited capacity • You will lose them Page 80-81

22. 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 Page 81

23. 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 Page 81

24. Section C Chapter 2 Storage Devices What’s the downside of hard disk storage? • Headcrash - 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 Page 83

25. 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 • Tapebackup - copy of data on hard disk stored on magnetic tape. Page 83

26. 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 Page 84

27. 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 • It is very durable Page 85

28. 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 Page 85

29. 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 • ideal for games, maps, large databases Page 86

30. 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 Page 87

31. 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 Page 87

32. 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 Page 88

33. 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 Page 92

34. 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. • Dotpitch - a measure of image clarity • smaller dot pitch means a crisper image • Resolution - number of pixels a monitor can display Page 93

35. 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. • Colorcapability • come in color or black and white Page 94

36. Section D Chapter 2 Input and Output Devices What features should I look for in a printer? • Printspeed • measured either by pages per minute (ppm) or characters per second (cps) • color takes longer than black and white • text prints faster than graphics Page 94

37. Section D Chapter 2 Input and Output Devices What features should I look for in a printer? • Printercost • printers for microcomputers range from $100 to $5000 • dutycycle - 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 Page 94-95

38. 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 printeris today’s most popular printing technology. • print head consists of a series of nozzles that sprays ink onto paper • What happens if it rains??? Page 95

39. Section D Chapter 2 Input and Output Devices Is a laser better than an ink jet? • A laserprinter 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 Page 95

40. Section D Chapter 2 Input and Output Devices Why would anyone want a dot matrix printer? • Dotmatrixprinters produce characters and graphics using impact • Cheap, cheap • low quality output • can print multipart carbon forms Page 96