Introduction to Personal Computers

Hardware

Thanks to Chris Wright and Don Campbell for the content of this presentation!

What Are Computers For?

Create DocumentsCreate PresentationsProcess Business TransactionsPerform analysis

Bottom Line: Computers are tools that allow users to increase their productivity.

What Does A Computers Do?

InputProcessingOutput

Bits & Bytes

Bit (a zero or 1)Eight Bits = One ByteOne Byte = One CharacterOne KB = 1,024 Bytes {1 Thousand}

One MB = 1,024,000 Bytes {1 Million}

One GB = 1,024,000,000 Bytes {1 Billion}

One TB = 1,024,000,000,000 Bytes {1 Trillion}

Remember Processing takes place one byte at a time

Personal Computer History

IBM offered PC in 1981Intel designed microprocessor for IBM platformMicrosoft designed operating systemOpen design created IBM PC Compatible marketApple – forced PCs to become more user-friendly.

What’s In a Computer?

Microprocessor (CPU)Internal MemoryAuxiliary StorageInput UnitsOutput Units

The Microprocessor (CPU)

The ‘brains’ of any computerCentral Processing Unit Where most computations take placeMade up of two main components:

Arithmetic Logic Unit {which performs arithmetic and logical operations}

Control Unit {extracts instructions from memory, decodes & executes them, calls on the ALU when necessary}

Performance is measured by clock speed; how quickly the CPU ‘cycles’ each second

Megahertz Gigahertz

CPU Performance

Performance is measured by clock speed; how quickly the CPU ‘cycles’ each second

One MHz = 1 million cycles per secondOne Gigahertz = 1 billion cycles per secondIndicates number of instructions the computer can handle per second

Data Bus WidthNumber of bits that can be transferred at one time64 Bit Bus can handle 64 bits per cycle

History of CPUs

8086 / 8088 (1981) – 8 Megahertz80286 {286}80386 {386}80486 {486}Pentium {586}Pentium IIPentium IIIPentium IV (2001) – 2 Gigahertz

Processor Performance

Main Memory

Memory - temporary, fast storage area that holds data, instructions, and results, and passes everything to the CPURandom Access Memory {Temporary Storage}

DRAM {Dynamic, less expensive, more common}

SRAM {Static}

Volatile Can be found in Printers or other devicesNeeds refreshing 1,000’s of times/second

ROM

Read Only Memory – like RAM, but staticData is prerecordedData can not be altered, only readNonvolatileContains the instructions a computer need to boot (Basic Input Output System)Can be found in printers or other devicesPROM (programmable), EPROM (erasable, programmable)

Auxiliary StoragePermanent storage of data/programsTypes includes

Hard disk = Fixed DiskGigabyte ~ 1 billion bytesAccess Time – not as fast as memory (which is 100 times faster) Today – cheap ($200-$300 for 40GB drive)

Floppy disksHigh Density = 1.44MB

Removable DisksCD ROM (650 MB)DVDSecond Hard DiskZip/Jazz (100MB to 1 GB)

Tape (Sequential storage) – typically used for backups

Internet Connections

ModemModulateDemodulate

Bit = binary digitbps = bits per secondFax/modem cardRecommendation: Buy at least 56K, High Speed Internet or Cable

Multimedia

CD-ROM Compact Disk, Read Only MemoryDVD Sound card needed for microphone and speakers

CD-ROMCPUExpansion slotsFloppy driveHard diskMemory chipMotherboardPower supply

Inside the Computer

Motherboard

The main circuit boardContains the CPU, BIOS, memory, expansion slots, ports, etc.

Input Devices

KeyboardMouseScannerTrackballJoystickPens

Output - Monitors

Output deviceTypesSizePixelResolutionDot pitchRefresh rateInterlaced / non-interlacedMulti-scanning

Monitor TypesMonochrome

One colour on black - old technology

ColourCGA

Colour Graphics Adapter - old technology - introduced in 1981 by IBM - could produce only 2 colours at a resolution of 640 x 200 - poor quality image - now obsolete

EGAEnhanced Graphics Adapter - old technology - introduced in 1984 by IBM - could produce 16 colours at a resolution of 640 x 350 - better than CGA but still poor quality image - now obsolete

VGAVideo Graphics Array - newer technology - introduced in 1987 by IBM - can produce 262,144 colours - resolution of up to 720 x 400 - All PC’s today support VGA

SVGASuper Video Graphics Array - new technology - can produce 16,000,000 colours - resolution of up to 1600 x 1200

Touch screenA type of display screen that has a touch-sensitive transparent panel covering the screen. Instead of using a pointing device such as a mouse or light pen, you can use your finger to point directly to objects on the screen

Size

Typical sizes are 14” - 15” - 17” - 19” - 21”Measured diagonallyPixel {short for picture element - smallest dot of light that a monitor can display}

Dot Pitch {measured in millimeters - it is the distance between each pixel - usually between .15mm to .30mm}

Resolution {the number of pixels on the entire screen - for example a monitor with a resolution of 640 x 480 is capable of displaying 640 dots on each of 480 lines on the screen}

Printers

Output deviceQualitySpeedImpact / Non-impactTypes

Types of Printers

Daisy WheelDot MatrixInk Jet / Bubble JetThermalLineLCD & LEDLaserPlotter

Daisy Wheel Printer

Impact, letter qualitySimilar to a ball-head typewriterA hammer presses the wheel against a ribbon, which in turn makes an ink stain in the shape of the character on the paper.Cannot print graphicsUses a ribbonSpeed measured in CPS {Characters Per Second}

Dot Matrix Printer

Impact, near letter qualityUses a ribbonComes in 9 Pin or 24 PinOne character at a timeSpeed measured in CPSNoisyGreat for multiple part forms

Creates characters by striking pins against a ribbon onto the paper

Ink-Jet Printer

Non-impact, letter qualitySprays ink on paperColourUses ink cartridgesOne line at a timeCan be very slow when high quality is desired

Line Printer

Impact, near letter qualityHigh speed - up to 3,000 lines per minuteCannot print graphicsVery noisy

Thermal Printer

Non-impact, letter qualityUses heat to transfer an impression onto paperUsed in early fax machinesOften found at retail outlets in the form of a receipt

Laser Printer

Non-impact, letter qualityUses tonerFull page printerSpeed measured in PPM {Page Per Minute}

Plotter

Not really a printerDraws pictures on paper based on commands from a computerContinuous linesUses pen(s)Normally used in engineering applications

The PC Today

Main Components1Gb microprocessor256Mb RAM30Gb hard drive1 floppy driveZip driveDVD or CD-ROM drive19” monitor *64Mb graphics card

Other ComponentsHS Internet / Cable modemCD-RW drive Sound card/speakersCameraMicrophoneTV adapter

Purchasing on the Web

www.dell.comwww.gateway.comwww.ibm.comwww.pcwarehouse.comwww.microwarehouse.com