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Computer Hardware
CHAPTER 2
Chapter 2: Computer Hardware 2
2 Chapter Contents
Section A: Data Representation and Digital Electronics
Section B: Microprocessors and Memory Section C: Storage Devices Section D: Input and Output Devices
Chapter 2: Computer Hardware 3
2 SECTION ASection A: Data Representation and Digital Electronics
Data Representation Quantifying Bits and Bytes Digital Electronics
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2 Data Representation
Process of transforming diverse data into a form computers can use for processing
Digital devices work with distinct and separate data
Analog devices work with continuous data
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2 Data Representation Numeric data
– Binary number system Character data
– ASCII, Extended ASCII, and Unicode (not used in arithmetic operations)
Digitizing is the process of converting analog data into digital format
File headers contain information about the code used to represent file data
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2 Data Representation
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2 Quantifying Bits and Bytes
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2 Digital Electronics
Bits take the form of electrical pulses that can travel over circuits
System unit
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2 Digital Electronics
An integrated circuit (computer chip) is a super-thin slice of semiconducting material packed with microscopic circuit elements
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2 Digital Electronics
The computer’s main circuit board is called the system board, or motherboard
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2 SECTION BSection B: Microprocessors and Memory
Microprocessor Basics Microprocessor Performance Factors Today’s Microprocessors Random Access Memory Read-only Memory CMOS Memory Buying a Computer
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2 Microprocessor Basics A microprocessor is an integrated circuit
designed to process instructions– ALU– Registers– Control unit– Instruction set(list of instructionsa microprocessorcan perform)
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2 Microprocessor Performance Factors Microprocessor clock (sets pace for executing instructions)
– Megahertz (millions of cycles per second)– Gigahertz (billions of cycles per second)
Word size (# of bits a processor can manipulate at a time) Cache (high speed memory where a processor can access data
quicker than memory located elsewhere)– Level 1 cache (L1)– Level 2 cache (L2)
CISC vs. RISC technology– CISC- complex instruction set computer– RISC- reduced instruction set computer. RISC is faster than CISC
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2 Microprocessor Performance Factors
Serial processing- processor completes all steps in the instruction cycle before it begins to execute the next instruction– Pipelining
Parallel processing
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2 Microprocessor Performance Factors
Dual core processors contain the circuitry for two microprocessors
Benchmark tests gauge the overall speed of a microprocessor
A microprocessor can operate at full efficiency only if all components in the computer can handle the faster speeds.
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2 Today’s Microprocessors
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2 Random Access Memory
Random Access Memory is a temporary holding area for data, application program instructions, and the operating system
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2 Random Access Memory
Microscopic capacitors hold the bits that represent data
Most RAM is volatile– Requires electrical power to hold data– Usually consists of several chips
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2 Random Access Memory
RAM capacity is expressed in megabytes or gigabytes
Personal computers typically feature between 128 MB and 2 GB of RAM
An area of the hard disk, called virtual memory, can be used if an application runs out of allocated RAM
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2 Random Access Memory RAM speed is often expressed in nanoseconds or
megahertz SDRAM is fast and relatively inexpensive
– DDR RDRAM is more expensive, and usually found in
high-performance workstations “Waiting room” for the processor
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2 Read-Only Memory
ROM is a type of memory circuitry that holds the computer’s startup routine– Permanent and non-volatile
The ROM BIOS tells the computer how to access to hard disk, find the operating system, and load it into RAM
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2 CMOS Memory
Stores basic system information More permanent than RAM, and less
permanent than ROM Requires very little power to hold data
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2 Buying a Computer
Assess your budge Think about how you plan to use your
computer Look at ads and visit online computer stores
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2 SECTION CSection C: Storage Devices
Storage Basics Floppy Disk Technology Hard Disk Technology Tape Storage CD and DVD Technology Solid State Storage
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2 Storage Basics
A storage medium contains data A storage device records and retrieves data
from a storage medium– Data gets copied from a storage device into
RAM, where it waits to be processed– Processed data is held temporarily in RAM
before it is copied to a storage medium
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2 Storage Basics
Magnetic storage stores data by magnetizing microscopic particles on the disk or tape surface
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2 Storage Basics
Optical storage stores data as microscopic light and dark spots (land and pits) on the disk surface– CD and DVD storage technologies
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2 Storage Basics
Solid state storage technology stores data in a non-volatile, erasable, low-power chip– Some solid state storage requires a card reader
to transfer data to or from a computer– Faster than optical or magnetic storage
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2 Storage Basics
Most desktop computers haveseveral drive bays, someaccessible from outside thecase, and others—designed forhard disk drives—without anyexternal access. Empty drivebays are typically hidden fromview with a face plate.
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2 Storage Basics Versatility Durability Speed
– Access time (often measured in milliseconds and is how long it takes a computer to locate data on storage medium and read it)
– Random vs. sequential access– Data transfer rate
Capacity– Kilobytes (KB), megabytes (MB), and gigabytes frequently
used today
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2 Floppy Disk Technology
Used for standard HD DS disks and Zip disks
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2 Hard Disk Technology
Hard disk platters are sealedinside the drive case or cartridgeto prevent dust and othercontaminants from interferingwith the read-write heads.
CLICK TO START
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2 Hard Disk Technology A controller positions the disk and read-write
heads to locate data– SATA– Ultra ATA– EIDE– SCSI
Not as durable as many other storage technologies– Head crash
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2 Tape Storage
A tape backup stores a copy of the data on a hard disk on a magnetic tape
A tape is a sequential storage medium
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2 CD and DVD Technology
A CD can hold up to 80 minutes of music or 700 MB of data
A DVD can hold about 4.7 GB of data A double-layer DVD can store 8.5 GB of data HD-DVDs can store 15 GB Blu-ray DVDs can store 25 GB
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2 CD and DVD Technology CD-DA DVD-Video CD-ROM DVD-ROM CD-R DVD+R or DVD-R CD-RW DVD+RW or DVD-RW
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2 CD and DVD Technology
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2 Solid State Storage (Portable)
USB flash drive CompactFlash (CF) cards MultiMedia cards (MMC) SecureDigital (SD) SmartMedia (least durable)
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2 SECTION DSection D: Input and Output Devices
Basic Input Devices Display Devices Printers Installing Peripheral Devices
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2 Basic Input Devices
Keyboard Pointing device
– Pointing stick– Trackpad– Trackball– Joystick
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2 Display Devices A CRT display device uses
a bulky glass tube (least expensive)
An LCD manipulates light within a layer of liquid crystal cells
Plasma screen technology illuminates lights arranged in a panel-like screen
On most monitors, the viewable image does not stretch to the edge of the screen
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2 Display Devices
Viewable image size Dot pitch Viewing angle width Refresh rate Color depth Resolution
– VGA, SVGA, XGA, SXGA, and UXGA
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2 Display Devices
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2 Display Devices
Graphics circuitry generates the signals for displaying an image on the screen– Integrated graphics– Graphics card
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2 Printers
An ink-jet printer has a nozzle-like print head that sprays ink onto paper
A laser printer works like a photocopier
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2 Printers
Laser printers are a populartechnology when high-volumeoutput or good-quality printoutsare required.
CLICK TO START
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2 Printers
Dot matrix printers produce characters and graphics by using a grid of fine wires– The wires strike a ribbon and the paper
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2 Printers Other printer technologies include solid ink printers,
thermal transfer printers, and dye sublimation printers
Printer features– Resolution– Print speed– Duty cycle– Operating costs– Duplex capability– Memory
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2 Installing Peripheral Devices The data bus moves data within the computer The expansion bus is the segment of the data bus
that extends between RAM and peripheral devices Expansion cards are small circuit boards that give
the computer additional capabilities– Expansion slot
• ISA (Old technology. Slower devices, not found on most new computers)
• PCI (32 or 64 bit. Graphics cards, network cards, and more)• AGP (Primarily used for graphics cards)• PCMCIA (Used in notebook computers)
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2 Installing Peripheral Devices
An expansion card simply slidesinto an expansion slot and is secured with a small screw. Before you open the case, make sure you unplug the computer and groundyourself—that’s technical jargonfor releasing static electricity byusing a special grounding wristbandor by touching both hands to a metal object.
CLICK TO START
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2 Installing Peripheral Devices An expansion port
passes data in and out of a computer or peripheral device
Peripheral device may include the Plug and Play feature, or require a device driver
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2 Installing Peripheral Devices
CHAPTER 2 COMPLETE
Computer Hardware