c hapter 2

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


2 SECTION ASection A: Data Representation and Digital Electronics

Data Representation Quantifying Bits and Bytes Digital Electronics


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


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


2 Data Representation


2 Quantifying Bits and Bytes


2 Digital Electronics Bits take the form of electrical pulses that can

travel over circuits System unit


2 Digital Electronics An integrated circuit (computer chip) is a

super-thin slice of semiconducting material packed with microscopic circuit elements


2 Digital Electronics The computer’s main circuit board is called

the system board, or motherboard


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


2 Microprocessor Basics A microprocessor is an integrated circuit

designed to process instructions– ALU– Registers– Control unit– Instruction set(list of instructionsa microprocessorcan perform)


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


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


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.


2 Today’s Microprocessors


2 Random Access Memory Random Access Memory is a temporary

holding area for data, application program instructions, and the operating system


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


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


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


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


2 CMOS Memory Stores basic system information More permanent than RAM, and less

permanent than ROM Requires very little power to hold data


2 Buying a Computer Assess your budge Think about how you plan to use your

computer Look at ads and visit online computer stores


2 SECTION CSection C: Storage Devices

Storage Basics Floppy Disk Technology Hard Disk Technology Tape Storage CD and DVD Technology Solid State Storage


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


2 Storage Basics Magnetic storage stores data by magnetizing

microscopic particles on the disk or tape surface


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


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


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.

CLICK TO START


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


2 Floppy Disk Technology Used for standard HD DS disks and Zip disks


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


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


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


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


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


2 CD and DVD Technology


2 Solid State Storage (Portable) USB flash drive CompactFlash (CF) cards MultiMedia cards (MMC) SecureDigital (SD) SmartMedia (least durable)


2 SECTION DSection D: Input and Output Devices

Basic Input Devices Display Devices Printers Installing Peripheral Devices


2 Basic Input Devices Keyboard Pointing device

– Pointing stick– Trackpad– Trackball– Joystick


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


2 Display Devices Viewable image size Dot pitch Viewing angle width Refresh rate Color depth Resolution

– VGA, SVGA, XGA, SXGA, and UXGA


2 Display Devices


2 Display Devices Graphics circuitry generates the signals for

displaying an image on the screen– Integrated graphics– Graphics card


2 Printers An ink-jet printer has a nozzle-like print head

that sprays ink onto paper A laser printer works like a photocopier


2 Printers

Laser printers are a populartechnology when high-volumeoutput or good-quality printoutsare required.

CLICK TO START


2 Printers Dot matrix printers produce characters and

graphics by using a grid of fine wires– The wires strike a ribbon and the paper


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


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)


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


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


2 Installing Peripheral Devices

CHAPTER 2 COMPLETE

Computer Hardware

c hapter 2

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