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Computer Hardware

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 performance Explain RAM Compare storage technologies Describe computer’s expansion bus

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Computer Hardware

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  1. 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 performance • Explain RAM • Compare storage technologies • Describe computer’s expansion bus • Explain hardware compatibility considerations • Compare and contrast technologies for peripherals Page 57

  2. Section A Chapter 2 Data Representation and Digital Electronics Digital Data Representation: Why are computers digital? • Data representation makes it possible to convert letters, sounds, and images into electrical signals • Digital electronics makes it possible for computer to manipulate simple “on” and “off” signals to perform complex tasks • A digital device works with discrete data or digits, such as 1 and 0 • An analog device works with continuous data such as sound waves Page 58

  3. Section A Chapter 2 Data Representation and Digital Electronics How can a computer represent numbers using bits? • Unlike the decimal system, the binary number system (base 2) uses only two digits 0, and 1. • The following table lists some decimal numbers and their binary equivalent: Page 59

  4. Section A Chapter 2 Data Representation and Digital Electronics How can a computer represent words and letters using bits? • Character data is composed of letters, symbols, and numerals that will not be used in arithmetic operations • ASCII (American Standard Code for Information Interchange) requires only 7 bits for each character • Extended ASCII uses eight bits for each character • EBCDIC (Extended Binary-Coded Decimal Interchange Code) is an alternative 8-bit used by older IBM systems • Unicode uses 16 bits and provide codes for 65,000 characters – a bonus for representing alphabets of multiple languages Page 59-60

  5. Section A Chapter 2 Data Representation and Digital Electronics When a computer works with a series of 1s and 0s, how does it know which code to use? • Most computer files contain a file header • A file header contains the information on the code that was used to represent the file data • It is read by the computer but never appears on the screen Page 61

  6. Section A Chapter 2 Data Representation and Digital Electronics Quantifying Bits and bytes: How can I tell the difference between bits and bytes? • A bit is one binary digit (b) • 0 • A byte is 8 bits (B) • 0010 0100 • A nibble is 4 bits • 0011 Page 61

  7. Section A Chapter 2 Data Representation and Digital Electronics What do the prefixes kilo- mega- and giga- mean? • Kilo- means a 1000, Mega- means million, Giga -means billion, Tera- means trillion, and Exa- means quintillion • Kilobit (Kb) is 1,024 bits • Kilobyte (KB) is 1, 024 bytes • Megabyte(MB) is 1,048,576 bytes Page 61

  8. Section A Chapter 2 Data Representation and Digital Electronics Does a typical computer owner need to mess around inside the system unit? Power supply and fan CD-ROM drive Floppy disk drive Microprocessor build under cooling fan Hard disk drive Cables that transfer data from storage devices to motherboard Expansion cards Main circuit board (motherboard) Page 62

  9. Section A Chapter 2 Data Representation and Digital Electronics What’s a computer chip? • Most electronic components inside a computer are integrated circuits- thin slices of silicon crystal packed with microscopic circuit elements • Wires • Transistors • Capacitors • Resistors Page 62

  10. Section A Chapter 2 Data Representation and Digital Electronics Types of Computer Chips DIP DIMM SEC PGA Page 63

  11. Section A Chapter 2 Data Representation and Digital Electronics How do chips fit together to make a computer? Expansion card Battery that powers the computer’s real-time clock DIMM module containing memory chips Connections for storage device cables Expansion slots hold additional expansion cards, such as a modem or sound card The motherboard houses all essential chips and provides connecting circuitry between them DIP holding a ROM chip Connector for power supply Circuitry that transports data from one component to another SEC-style microprocessor Page 64

  12. A microprocessor is an integrated circuit designed to process instructions CPU on a chip 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. Section B Chapter 2 Microprocessors and Memory Microprocessor Basics: Page 66

  13. Section B Chapter 2 Microprocessors and Memory Where does the microprocessor get its instructions • The microprocessor executes instructions provided by a computer program • The list of instructions that a microprocessor can perform is called its instruction set Page 67

  14. 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 • Word size • Cache – Level 1, Level 2 caches • instruction set size Page 67-68

  15. Section B Chapter 2 Microprocessors and Memory What’s the difference between CISC and RISC? • Computers based on a CPU with a complex instruction set known as CISC (complex instruction set computer) microprocessor • Intel • A RISC (reduced instruction set computer) has limited set of instructions that it can perform quickly • AMD Page 68

  16. Section B Chapter 2 Microprocessors and Memory Can a microprocessor execute more than one instruction at a time? • Computers with a single processor execute instructions serially (one at a time) • Pipelining - technology in which the processor can begin executing the next instruction before it completes the previous instruction • A computer with more than one processor can execute multiple instructions simultaneously, referred to as parallelprocessing Page 68

  17. Section B Chapter 2 Microprocessors and Memory With so many factors to consider, how can I compare microprocessors? • Testing laboratories run a series of tests (benchmarks) to gauge the overall speed of a microprocessor • The results are published on the Web and in computer magazine articles • Benchmarks can be downloaded and run on home systems as well Page 68

  18. Section B Chapter 2 Microprocessors and Memory Which microprocessor is best formy computer? • AMD and Intel are comparable • Pentium 4 • Itanium • Celeron • Athlon • Opteron • Duron • The microprocessor that’s best for you depends upon your budget and the type of work and play you plan to do Page 69

  19. 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 Page 70

  20. Section B Chapter 2 Microprocessors and Memory How does RAM differ from disk storage? Page 71

  21. Section B Chapter 2 Microprocessors and Memory How much RAM does my computer need? • RAM is primary storage (main memory) • Measured in megabytes (MB) or gigabytes (GB) • Today’s computers have between 128 MB and 2 GB of RAM • Depends on software you use • You can purchase additional RAM • A computer can use disk storage to simulate RAM. This is called virtual memory • Not as fast as RAM Page 71

  22. Section B Chapter 2 Microprocessors and Memory Do all computers use the same type of RAM? • No. RAM components vary in speed, technology, and configuration • Speed is measured in nanoseconds. 1 nanosecond (ns) is 1 billionth of a second • It can also be expressed in MHz (millions of cycles per second) • SDRAM (Synchronous Dynamic RAM) • RDRAM (Rambus Dynamic RAM) Page 72

  23. Section B Chapter 2 Microprocessors and Memory Do all computers use the same type of RAM? • RAM is usually configured as a series of DIPs soldered onto a small circuit board called a DIMM (dual in-line memory module), RIMM (Rambus in-line memory module), or SO-RIMM (small outline RIMM) • DIMMs contain SDRAM, RIMMs and SO-RIMMs contain RDRAM SDRAM chip Page 72

  24. Section B Chapter 2 Microprocessors and Memory Read-Only Memory: How is ROM different from RAM? • ROM (read-only memory) is one or more chips containing instructions that help a computer prepare to process tasks • ROM is permanent and non-volatile • Only way to change the instructions on a ROM chip is to replace the chip Page 72

  25. Section B Chapter 2 Microprocessors and Memory If a computer has RAM, why does it need ROM too? • 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

  26. Section B Chapter 2 Microprocessors and Memory CMOS memory: Where does a computer store its basic hardware settings? • A computer needs a semi-permanent way of keeping boot data, such as the number of hard disk sectors and cylinders • CMOSmemory - holds data but requires very little power to retain its contents • Retains important computer settings after you turn the power off • Can run by a battery on the motherboard • Housed within the same chip carrier as ROM BIOS Page 73

  27. Section B Chapter 2 Microprocessors and Memory Where does a computer store its basic hardware settings? Page 73

  28. 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

  29. 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

  30. 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

  31. Section C Chapter 2 Storage Devices What’s the difference between magnetic and optical storage technologies? • 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 more susceptible to environmental damage CD-ROM: PITS Page 78

  32. Section C Chapter 2 Storage Devices Can I add storage devices to my computer? • Devices can be added into empty drive bays An empty 5 1/4” drive bay located on the front of a desktop computer An empty 3 1/2” drive bay An empty drive bay located on the side of a notebook computer Click to start Page 78

  33. Section C Chapter 2 Storage Devices Which storage technology is best? • Versatility • Can access data from different media • Durability • Less susceptible to damage • Storage capacity - maximum amount of data that can be stored on a storage medium • Speed-measured by access time and data transfer rate • Access time- average time it takes a computer to locate data and read it • millisecond = one-thousandth of a second • Random access- ability of a device to jump directly to the track or sector holding the data • floppy disk, hard drive, CD, DVD, zip disks Page 79

  34. 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, 250 MB, and 750 MB • Superdisks – 120 MB or 240 MB Superdisk ZIP disk Page 80

  35. Section C Chapter 2 Storage Devices How does a hard disk work? • Hard disk platter- a flat, rigid disk made of aluminum or glass and coated with magnetic oxide • Density far exceeds floppy disk • Harddisk - one or more platters and their associated read-write heads. • Preferred type of main storage Page 81

  36. Section C Chapter 2 Storage Devices What’s all this business about Ultra ATA, EIDE, SCSI, and DMA? • A hard drive mechanism includes a circuit board called a controller that positions the disk and read-write heads to locate data • Popular drives • Ultra ATA (AT attachment) • EIDE (enhanced integrated drive electronics) • SCSI (small computer system interface) • Data Transfer: • DMA (direct memory access) technology allows a computer to transfer data directly from a drive into RAM without intervention from the processor • UDMA (ultra DMA) is a faster version of DMA technology Page 82

  37. 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 • Not limited to hard disks Page 83

  38. Section C Chapter 2 Storage Devices Can I use a second hard disk drive as a backup? • Removableharddisk - hard disks that can be inserted and removed from drive • Increase storage capacity • Provides security for data • RAID- (redundant array of independent disks) • Type of hard disk storage • Found on mainframe and microcomputer installations • Contains many disk platters • Provides redundancy • Faster data access Page 83

  39. Section C Chapter 2 Storage Devices Tape Storage: What’s the purpose of a tape drive? • Tape - most popular form of storage in 1960s • Recent revival in tape storage for backing up data, not for principal storage device. • Tapebackup - copy of data on hard disk stored on magnetic tape. • Sequential access • Inconvenient and slow • Data is arranged as a long sequence of bits that begin at one end of the tape and stretches to the other • Has a directory at the beginning or end of the tape that catalogs contents Page 83

  40. 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 • A single CD-ROM holds up to 650 MB • It is very durable if handled carefully • Original CD-ROM had speeds of 150 KB per second • Today, speeds of 24x or higher (24 x 150 KB per second) • Newer models should be over 50x Page 84

  41. 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 • 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

  42. Section C Chapter 2 Storage Devices Can I create my own CDs? • CD-RW (compact disc-rewritable) allows you to write on a CD, then change the data • Requires special CD-RW disks • Requires special CD-RW drive • Requires phase change technology • Phase change technology- alters the crystal structure on the disk surface Page 86

  43. 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 • Ideal for games, maps, large databases Page 86

  44. 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

  45. 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 • I/O(computer jargon for input/output) refers to collecting data and transporting results. • Expansion bus- the segment of the data bus that transports data between RAM and peripheral devices Page 88

  46. Section D Chapter 2 Input and Output Devices What is an expansion slot? • Expansion slot- long, narrow socket on the motherboard into which you can plug an expansion card • Graphics card (for connecting monitor) • Modem (for transmitting data over phone or cable lines) • Sound card (for connecting speakers) • Expansion card- small circuit board that provides computer with ability to control storage, input or output device • Most computers have 4 - 8 expansion slots Page 88-89

  47. Section D Chapter 2 Input and Output Devices What is an expansion slot? Click to start Page 88

  48. Section D Chapter 2 Input and Output Devices What are the major types of expansion slots? • The microcomputer motherboard typically has up to three types of expansion slots: • ISA - older technology, modems and slow devices • PCI - for graphics, sound, video, modem or network cards • AGP- for graphics cards • Expansion cards are built for only one type of slot Page 89

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