IT Applications Theory Slideshows IT Applications Theory Slideshows Roles of hardware and software components Roles of hardware and software components By Mark Kelly email@example.com Vceit.com Version 2 By Mark Kelly McKinnon Secondary College Vceit.com
Information Systems Information System components: • Hardware • Software • Procedures • People • Data Usually systems are computers May be specialised e.g. railway ticket machines
Hardware? Software? • Hardware is physical • E.g. a monitor • Can be touched, seen, picked up, kicked • Hardware needs software to operate • Software is programming instructions • E.g. Adobe Photoshop • Recorded as electronic binary signals • Controls hardware’s behaviour
Unofficial ICT Hardware Categories • Input • Output • Processing • Storage • Communication
Input Devices Let users enter data into an information system. • Keyboard, keypad • Mouse, touchpad • Bar code reader • Touch screen • Data tablet • Scanner, camera • Voice recognition
Input Devices • Keyboard, keypad • QWERTY layout. Designed to be as inefficient as possible to stop fast typists jamming the early typewriters • Dvorak – more efficient key layout puts most commonly used keys on the home row. Rare!
Input Devices • Mouse, trackball • Designed for GUI OS • Ball mouse superseded by optical • RSI concerns • Trackball = stationary upside-down mouse • Touchpad • When mice are impractical • On laptops
Input Devices • Bar code reader • Reads bar codes – converts them to numbers • Common in supermarkets, libraries, parts warehouses etc • Much faster and more accurate than hand-typing product codes
Input Devices • Touch screen • Touch sensitive • Tablet computers • iPhone • Railway ticket machines • Information kiosks • Bank ATMs • Easy for public to use • Can mimic any sort of interface: buttons are only images
Input Devices • Data tablet • Far better than a mouse for art • Works like a pen • Pressure-sensitive
Input Devices • Scanner, digital camera • Digitisesanalogue documents or pictures • Scans page like a photocopier • Use OCR (Optical Character Recognition) to interpret and digitise printed text • Resolution determines how detailed the resulting digital image is. • 1200 dpi resolution = 1200 dots per inch (2.54cm)
Voicerecognition1 • Modern form of dictation • Requires complex programming to recognise voices accurately • Users need to train software to get used to their accent • Not useful in noisy environments, e.g. offices
Voicerecognition2 • Not good for sensitive material – would be overheard! • May be useful if hands-free data entry needed • May be quicker data entry for poor typists
Output devices 1 Display the results of processing. • Monitor • CRT • LCD, TFT • Plasma • Data projector
CRT monitor • Now extinct!
LCD monitors • LCD = Liquid Crystal Display • Thin, saves desk space • Lighter than CRT • Less power consumption than CRT • Getting cheaper • Refresh rates getting better • Blacks often just grey • Colour richness not as good as CRT
Plasma • Very power-hungry • Cheap for very large displays (e.g. >40 inches) • Better blacks than LCD • Faster refresh than LCD • Good for public notice boards 150” (375cm) plasma display
Data Projector • Very portable • Very large display • Struggles in brightly lit rooms • Colours are often dull • Excellent for group presentations • Lamps fail with age
Output devices 2 • Printer • Laser • Inkjet • Thermal • Dot matrix, Impact • Speakers • Indicators, LEDs
Laser Printers 1 • Black and white or colour • Expensive to buy, cheaper to run than inkjet • Fast printing • Prints whole page at a time, not line by line like inkjet
Laser Printers 2 • Very high resolution (dots per inch) • Print is waterproof (unlike inkjet) • Same mechanicals as a photocopier
Inkjet Printers • Cheap to buy, very expensive to replace ink • Line-by-line printing
Thermal Printers • Low power requirements • Low to medium resolution • Can be battery powered - good for portable printing e.g. parking tickets • Uses heat-sensitive paper, usually on a roll
Thermal Printers • Not good for archive documents – paper blackens over time • Often used for bar coding boxes,Point Of Sale (POS) terminals
Dot matrix printers • Alias impact printer • In the print head are pins arranged in a matrix • They shoot out to hit an inked ribbon which is pushed against the paper leaving dots on it • Noisy! Slow! • Low resolution! Expensive ribbons… • but…
Dot matrix printers • The only printer type that strikes the paper… • Only they can produce duplicates with pressure-sensitive paper • E.g. supermarket receipts - two or three copies (white customer copy, yellow shop copy) in only one print operation
Other output devices • Speakers • Can use sound to give system alerts & information • Needed for playing audiovisual multimedia • Screen-recorded tutorials use voice-overs • Indicators, LEDs • Caps Lock, NumLock, hard disk activity, “power on” light etc • Watches, digital clocks • Car instrumentation
Processing Hardware Converts data to information • CPU • RISC, CISC • Multicore • GPU
CPU • Central Processing Unit • Most are CISC (Complex Instruction Set Computer) • Lots of inbuilt commands • Some are RISC (Reduced Instruction Set Computer) • Fewer inbuilt commands, simpler design • Smaller size, less power, less heat
CPU • Many now have 2 or more cores – equivalent of multiple CPUs for extra processing power • Speed measured in hertz (cycles per second) • The more the hertz, the more work gets done in a fixed time • Usually measured in gigahertz • 2 to 4 GHz common nowadays
CPU • Speed also can be measured in FLOPS • Floating Point Operations per Second • Benchmarks – standardised tests to measure CPU and whole-system performance.
GPU • Graphics Processor Unit • A video card’s processor – much more powerful than a CPU (300%) • Needs power to shift huge quantities of data to the monitor
GPU • Needs power to process complex video data (especially for gaming) • Now being used to help the CPU do processing • See nVidia’s Tesla – a GPU PC! 120 times more powerfulthan a normal PC.
Storage hardware Stores & retrieves data and software. • Hard disk • Solid state disk • Flash RAM, RAM, ROM • CD, DVD • Tape, floppy disk
Hard Disk Drive • ‘HDD’ • Magnetic storage • Multiple aluminium platters stacked on a spindle • Average HDD platters 3½” (inches) • Laptop platters 2½” • MP3 players 1”
Hard Disks • Read/write heads move across top and bottom of each platter • Spin at 5,400, 7,000 or 10,000 rpm • Head floats on a cushion of air a couple of molecules distance from the platter A hard disk drive head resting on the disk platter.
HDD • Very fast storage & retrieval • Very large capacity - 1.5 Terabytes • 1,500 gigabytes • Very cheap per megabyte • Must be handled gently • Draw quite a lot of current, reducing battery life
SolidStateDisk • SSD • Permanent storage in Flash RAM • No moving parts – rugged & portable • Draw less current than HDD – longer battery life • Speed can be better than HDD • Expensive ($AU) • 128G SSD = $650 (2010) $235 (2011) • 1000G HDD = $77 (2011) • Small capacity compared to HDD
USB Flash Drives • NAND memory • Normal RAM (Random Access Memory) loses its memory contents when power is turned off • Normal ROM (Read Only Memory) has its contents burnt at the factory and they cannot be changed later
USB Flash Drives • Flash RAM can be rewritten like RAM but its contents are retained when power is lost. • Completely replaced floppy disks • Limited life – 1 million read/write cycles • 10 year data retention
USB Flash drives • Small, light, rugged (sealed, no moving parts) • Cheap ones can be rather slow • Typical capacity from 64M to 64G. • Easily lost or left behind - possible security issues • Some USB Flash drives can be encrypted
CD, DVD • Compact Disk – capacity about 700M • Digital Versatile Disk – about 4.7G (4700M) • Come in writeable and rewriteable forms • Writeable (CD-R, DVD-R) can be burnt (written to) once only – contents become permanent • Rewriteable (CD-RW, DVD-RW) can be erased and re-burnt several times.
CD, DVD • Aluminium layer embedded in a 5¼” polycarbonate plastic disc • Laser burns data digitally as pits • Data also read by laser beam • Continuous, spiral datatrack extends from innermost to the outermost track, covering the entire disc surface
CD, DVD • Sensitive to scratches, heat • Immune to magnetic effects • Not “perpetual storage” as originally believed. • Disks degrade over time, become unreadable • Gold disks seem to last longer The laser lens in a CD drive
DVD • DVD media come in 3 types: • DVD-R • DVD+R • DVD-RAM • Also come in single/double layer versions • Most burners can write all 3 formats • Most players can play all 3 formats
Blu-ray • Uses blue laser rather than red • Narrower beam can write more data in the same space • Compare writing with a thick red crayon and a sharp blue pencil
Tape & Floppy Disk • Magnetic storage – data can be damaged by magnetic fields; data can fade over time until it becomes unreadable • Read/write head rubs on the media surface – eventually wear off the magnetic coating
Tape & Floppy Disk • DAT (Digital Audio Tape) commonly used for backup in corporate networks • Floppy disks – slow, low capacity, unreliable, expensive. EXTINCT.