Computer Hardware Platforms and Systems Book Source: Unit A pg 14-17
The basics- Hardware • Computer hardware is any part you can see and touch (or kick) • A peripheral is any piece of hardware attached to a computer eg printer, scanner and mouse
Software • The set of electronic instructions that tell a computer what to do • Application software - lets you accomplish specific tasks such as word processing, graphic design. • Operating system (OS) software - controls the overall activity of the computer eg starting up the computer, managing the organisation of your files, user interface, access to control panels eg monitor and sound
Common types of computer systems • Wintel(Windows/Intel), IBM compatible • PC or Personal Computer • originally adopted widely in engineering and the sciences for quick computation • open standard • more competition -> most users • Macintosh • often used in schools, graphic design, desktop publishing • one of the first machines to provide the Graphic User Interface (GUI) and graphics capability. • standards controlled by Apple -> reduced competition
Operating systems • Mac • System 8, OS9, OS X • PC (WINTEL) • Home: DOS, W3, W95, W98, WME, WXP • Business: NT,W2000, WXP • Unix / Linux • Cross-platform • cooperation (works on multiple OSs)
Input Processing Output Storage How computers work • Input • input devices allow the computer to receive: • information (data) • commands (instructions) • eg keyboard, mouse, joystick.
ENIAC • Completed in 1947 • Weighed over 16 tons • No Monitor
Input - First mouse • Doug Englebart invented the computer mouse in 1965. • Made of wood
Input - Digital Camera still and/orvideo
Input continued • scanners • touch screen • audio input • network • modem • VR • ...
Processing • The Central Processing unit (CPU) • The “brain” of the computer • processes instructions, • performs calculations, • manages the flow of information, • communicates with input, output and storage devices.
CPU- Central Processing Unit • performs millions of calculations per second • complex, eg a road map on a finger nail • Speed measured in Megahertz (MHz) = millions of cycles per second. • up to 1500+ MHz • MHz is only an estimate of processing speed • real measure of computing speed should be related to the performance of tasks (not just MHz)
CPU- Central Processing Unit • up to 1500+ MHz • MHz is only an estimate of processing speed • real measure of computing speed should be related to the performance of tasks (not just MHz)
Storage –Memory– RAM • temporarily stores data • new programs must be loaded into memory before they can run • the amount of memory determines the number of applications that can run at the same time • extra RAM can speed up processing • virtual memory– on disk – slower • 128+ MB is current standard • 256+ MB for serious digital processing
Storage (Secondary Storage) • A storage device holds the information so that the computer can perform its tasks • examples of storage devices are the hard drive and floppy disk, zip
Storage –Hard Drive • main storage device • long term memory • consists of a stack of rotating disks called platters • has several read/write heads • stores programs and data in files • storage capacity measured in bytes (MB, GB), commonly 10GB to 80GB • new high speed drives to mount on more than one computer at a time
CD ROM drives • hold around 650-800 MB data(74 minutes of music as an audio CD) • Read Only Memory - information can’t be changed • Used for installing programs, playing music, multimedia software
CD ROM developments • CDR – Recordable (Make your own CDs) • CDRW – Rewritable (Delete and change CDs) • CD-Write and Rewrite • frequently used to back up information • DirectCD – use CD just like a floppy – drag and drop files • New generation • DVD- Digital versatile (video) disk
DVD • distribution medium designed for digital video • superior audio and video quality • enough data for up to nine hours of studio-quality audio and video • 4 to 26 times the data on an audio CD • MPEG(2) is the video format used • interactive -eg multiple camera angles possible, different languages, subtitles…
DVD Technology • More storage because data is packed closer together (the laser is finer so it can read this data)
DVD Technology • data is recorded on two layersand also on both sides
Output • Output devices communicate with us(imagine a computer with no output!) • monitor • printer • speakers (headphones) • aroma dispenser (?) • VR headset, force feedback • Network / Modem • ...
Display Technologies • Cathode Ray Tubes (CRT) • Flat-Panel Displays • Emissive - Plasma • Non Emissive - LCD • Future… ?
Colour CRT Monitors 3 Beams - for Red, Green, Blue Beam Penetration (Vector) Shadow Mask (Raster/TV) Tension Mask (Trinitron)Aperture Grille
Monitor/Image Issues • Resolution • max. number of pixels • 800x600, 1024x768, 320x240 etc. • Dot Pitch • Space between pixels (e.g. 0.26mm) • Colour Depth • number of bits used to store colour per pixel – gives the number of colours possible
Monitors • size is measured diagonally across the screen, commonly 14, 15, 17, 19 and 21”. • larger monitors are ideal for desktop publishing and working with graphics/multimedia • refresh rate is the speed the monitor redraws, preferably 72Hz or more. • Hertz is a unit of frequency, equal to one cycle per second • new monitors - high refresh rate - image appears very stable
Components of a CRT • Electron gun (heated cathode + control grid) • Focusing system • Accelerating system • Deflection system • Phosphor-coated screen
Resolution • Pixel (picture element) - smallest element • resolution is measured by number of vertical and horizontal pixels • 640 x 480 (307,200 ) • 800 x 600 • 1024 x 768 • 1280 x 1024 • 1600 x 1200 (1,920,000) • nearly 2000000 pixels • high demand on CPU for video
Colour depth • 4 bit = 16 colours (2 to the power of 4) • 8 bit = 256 colours (2 to the power of 8) • 16 bit = 65, 536 (thousands of colours) • 24 bit = 16,777,216 (millions of colours) • Most people can not easily discern between thousands and millions of colours on the computer screen. • millions of colours are required for printing and broadcast video output • video • more colours - more demand - some video playback better at lower colour depth
Bytes • All information is stored as binary digits or bits which are on/off signals. • Eight bits of data combine to form one byte, as a character; number, letter, or symbol • One kilobyte (K/KB) is 1,024 characters, approx. equal to one page of double-spaced text. • One megabyte(MB) is 1,048,576 characters, approximately equal to one novel. • One gigabyte(GB) is 1,073,741,824 characters, approximately one thousand novels.
Inside the computer • The power supply converts AC to DC • Hard drive- primary storage device • Motherboard- main circuit board that all the components plug into. • Expansion card- plugs into expansion slots, to increase the computers functionality eg video or sound cards • Central Processing Unit • Random Access Memory - RAM temporary storage • Floppy/ZIP drive (future?)
Readings • Unit A– pages 14-17