2. Types of Computers  Supercomputers  Mainframe  Personal Computer  Laptops  Embedded Computers  PDA

3. Super Computers  Supercomputer can be as big as a generator  Fastest and most expensive (100 million pounds +)  Very few organizations can afford one  Large universities and weather stations have supercomputers to carry lots of data and research  Pharmaceutical companies use supercomputers for drug research  Supercomputers are used mostly for research  SC generate a lot of heat, which means they need to be housed in cool rooms and the air in the room has to be very clean  VERY expensive and sensitive  Use a lot of cables  Need their own backup electricity power to ensure they work if there is a power failure  Use a lot of power and electricity

4. Mainframe Computers  Large powerful computers that carry out many different tasks for different people  Slower than supercomputers and less expensive  Can execute billions of instructions per second  Can process large amounts of data simultaneously  Usually connected to lots of terminals, printers, disk drives, etc.  Big schools may use mainframe computers for student information  Airlines for bookings, tickets, cancelations  Police for storing data about crimes committed everyday  Banks use mainframe to manage thousands of customer accounts each day  Utility companies (Gas, Water, Electricity, Service Charge) use mainframe to calculate customer bills  Must be operated by specialist and experts  Must be kept in an air conditioned room when in use  Kept away from floor because they want to stop currents from entering the floor

5. Personal Computers  In the past they were called micro computers  Now they are called PC’s or Desktops  Desktop PC consists of a monitor, tower unit, keyboard, and a mouse  Modern PC’ s are powerful, they can carry out millions of calculations per second Uses Of PC’s: Office Applications (Word Processors, Spreadsheets) Creating and playing music Making and editing movies Taking pictures Accessing the internet for research or leisure CAD (Computer Aided Design)

6. Laptops  Are more expensive in comparison to PC’s  When they first came out they were very expensive but for the high demand for them they reduced in price  People’s work patterns and living patterns make most people have laptops  People use laptops to carry on working whilst they are traveling from one place to another  Becoming an essential in people’s everyday lives  Modern laptops use wireless networking, which makes it easy for people to move around with them  When laptops first came out the batteries didn’t last long, but now they last for longer periods of time  Early laptops were large, bulky, and heavy to carry around  Laptops designs have improved causing them to become compact and light to carry

7. PDA (Personal Digital Assistant)  Originally designed as a digital organizer  People have developed the PDA further to make it more like a computer  Can send emails, play games, use word processors  Similar to Palm Tops, except palm tops that have a keyboard

8. Embedded Computer  Is a single chip that contains all the elements that are essential for any computer Essential Elements For A Computer: RAM (Random Access Memory) ROM (Read Only Memory) CPU (Central Processing Unit) Input Device Output Device Clock Power Supply  Can also be called a Micro Controller  Main purpose of an embedded computer is to control something  Televisions, camera’s, washing machines, microwaves, phones have embedded computers

9. Manual devices

10. Keyboard  There are many different types of Keyboards  The Keyboard is made up of buttons called keys e.g. letter symbols, function keys, command keys. Advantages of keyboards:  Types in data quickly  Very little training is needed  Specialist keyboards are available such as an ergonomic Disadvantages of keyboards:  Easy to make mistakes  Not suitable for creating diagrams  Disable people often find keyboards difficult to use  Using a keyboard for a long time it might lead to RSI

11. Mouse  Also called pointing device  Most common input device  The mouse has 2 buttons and a central wheel  Works by tractable movement Advantages for mouse:  Is supplied with a desktop  Requires very little training  Works well with the keyboard Disadvantes for a mouse:  Needs a flat surface  If the tracker ball gets dirty it will stop working  Using the mouse too often can lead to RSI

12. Touchpad  Is found on a laptop computer  It can be used as a mouse  It works by dragging your finger over it  It reacts to slide heat  You can control it with your finger Advantages of a touchpad:  Useful for laptops  The positions of the touchpad is fixed  Very short finger movements are required Disadvantages of a touchpad:  Moist and sweaty fingers can disrupt the signals picked up by the sensors  Gloves cant be worn  Takes practice and skills to control the position of the curser

13. Joystick  Allows you to tell the computer which direction to make the pointer move on the screen  Many games are controlled by joystick  Pilots use joysticks for controlling an aircraft Advantages of a joystick:  Gives a better gaming experience Disadvantages of a joystick:  It can break easily  More difficult to control than a mouse

14. Scanner  Can be used to convert images or text on paper into a digital format  that can be used on the computer  Works by shining a light beam onto the surface of the object that you are scanning  The light is then reflected back onto a sensor that detects the color of the light, this is then used to build a digital image  Optical Character Recognition (OCR) can be used to convert text on paper into text which can be edited on a word processor  So people that want to make a copy of something (Picture, Certificate) you would scan the picture and it will scan it on the computer  Three types of scanner: Flat Bed and Handheld and Biometric  The most popular is the flat bed  Handheld scanners or used commercially (Shops, Stores, Checkout tills)  Biometric is used to scan things of the body (Thumbs, Eyes, Etc.)  Normally used for security

15. Digital Camera  Records images electronically on a memory card, rather than on a film  The images can be downloaded from the memory card onto the computer  You can change them with photo editing soft wear  Most digital cameras let you view the pictures before you print them  The quality of the image depends on the resolution or the number of megapixels  Two types of graphic images: Bit Mapped Images and Vector Based Images  Many digital cameras can take video clips along with sound Advantages of a Digital Camera: Don’t need film Images can be view immediately and deleted immediately Images can be edited and formatted Extra memory or memory sticks can be used to store images Images can be incorporated onto websites or documents Disadvantages of a Digital Camera: Can be expensive When the memory is full the images must be downloaded or deleted

16. Graphics Tablet  Often used by graphic designers and illustrators  Using a stylus pen to draw on a screen  More natural and accurate drawings can be made  Consists of a flat pad and stylus pen Advantages of a Graphic Tablet: Much more natural to draw with Drawings can be more accurate Disadvantage of a Graphic Tablet: Not used for selecting or clicking on menu items

17. Microphone  Can be used to input sound  The sound is detected by the microphone and an electrical signal is sent to the computer

18. Concept Keyboard  Is a flat board that contains a grid of buttons  The program for each button is programmed to do a particular task  People that work in fast food restaurant use these kind of keyboards  Used when fast input is needed  Useful for people who find a normal keyboard difficult  Also factories use concept keyboards  Its much faster  The keyboard is waterproof  Very poor for text  Its limit to the option shown in the keyboard

19. Automatic Input Devices

20. Magnetic Ink Character Reader (MICR)  The soft wear it uses is called Magnetic Ink Character Recognition  Find this on credit cards (Black stripe on back of credit cards)  MICR reads magnetic stripes and magnetic ink  The stripe contains information about account holder  The cards is put into a reader and reads the information  The reader can read the ink on data on passports  You need special soft wear for the computer to read what has been inputted and its called MICRS (Magnetic Ink Character Recognition Software)  Chip and Pin are used in bank cards  Its very expensive

21. Optical Mark Readers (OMR)  Used to detect marks made in pencil on preprinted documents  Its expensive  Sometimes they use them in exams  Its quick, easy, and accurate but sometimes if the document is damaged it can’t be read properly  Fast method of imputing a large amount of data

22. Sensors  Devices that input data from the physical environment  Two Types: Measure things that human beings can detect, and sensors that detect things humans can’t Main sensor types are: Temperature Light Magnetism Touch Radar Microwave Sound

23. Optical character recognition  Software that goes with scanners  Converts it into digital data  Its cheaper than paying someone to type the text  Its faster if someone text it  It can also re-create tables  You need very good quality OCR software to be able to read the text accurately

24. Output devices

25. Monitors  They come in different shapes, sizes and forms  The picture on a monitor is made up of very tiny dots, called pixels.  The higher numbers of pixels the better the output  Larger monitors make working on the computer easier on the eye, but its more expensive 2 types of monitors: Cathode Ray tuned monitors TFT monitor  TFT monitors are quieter, but it can damage easier than CRT monitors.  Sometimes they are noisy  They produce a lot of heat  The quality of a TFT screen isn't that clear as a CRT monitor

26. Printers  We use printers to hard copy our work Types of printers: Lasers printer Ink Jet Printer  Many people use them, because they are quiet, print quickly and produce high quality prints  There a black and white printers, they are much cheaper than color printers.  The cost for page is low  Very expensive  The toner is very expensive  Expensive to repair  They are very heavy

27. Ink Jet Printer  They are very cheap to buy  The ink isn't expensive  The ink is wet  Many homes use them  More compact, you can easily carry it around  Cheaper to replace  Nosier than laser printer  Color printing is sometimes slow  Cost for print out per page is more expensive  You need to replace the toner more often  The toner can dry out when you don’t use the printer  The color is not the same, when you print out the paper

28. Dot Matrix printer  Very noisy  They are cheap to buy  They are very strong  They are used in dirty places e.g. factories  The print quality is poor  They are very slow  They cant print out color print out

29. Plotter  Plotter can draw high quality images  Engineers use them  Map makers use them  Architects use them  It uses a pen to draw  Print out large images  They are slower than all the other printers  Each line is drawn separately  More expensive than any other printers  Not very good at printing text Types of Plotter: Flat bed plotters Drum plotters Pinch roller

30. Computer memory

31. Bits and bytes  Data can be stored and measured in bytes  One bytes can contains 8 bytes  A bits can only be 0 or 1  A series of 0 and 1 is known as a binary code  Every key character has a binary code  Computers only understand binary code e.g. the word BAG will occupy 3 byte memory  each storage location contains data such as a number, a character or a string of characters, computer instruction, part of a picture or another address of data  One thousand and twenty four bytes make up a kilo bits

32. Types of memory  ROM (Read Only Memory)  Its permant, which means it doesn’t change or erase  Its know as a “Non Volatile Memory”, because it doesn’t disappear after switching your computer off  ROM are not device or physical things  RAM (Random Access Memory)  Its different because its temporary  Only works when the computer is switched on  Its know as a “Volatile Memory”  Nothing is stored permant on RAM  They both store data inside the computer

33. Data storage

34. Internal Backing Store  Hard disk are the main Internal Backing Store  Hard disks have large storage capacity  Are found inside the computer

35. Floppy disk drive  Are not common anymore  It can be easily stored  Its not recommended  Is a magnetic device

36. CD-ROM and CD- Write  CD-ROM (Compact Disk Read Only Memory)  You can store data once, you cant add  You can burn music and movies on to it  They are optical devices  Memory capacity 700 MG  Make sure you buy the right format Types of CD’s:  CD write or also known as CDW

37. Flash drive  They are small and light  They are portable, removable and re-writable  They use a USB port on the computer to transmit or receive data  They are more fashionable looking  Easy to transmit viruses  if you put it near a metal all your data will be erases  You can easily lose your Flash Drive  Its more expensive than CDs and DVDs  It’s a optical device

38. DVD  DVD- Digital Versatile disk  Very similar to CD’s  The memory contains more space  You can store on one side and on the other side  Make sure you buy the right format  Produces a better quality of sound and image  Are now very cheap  A DVD player can read CDs and DVDs, but a CD player cant read a DVD  There are many DVD formats  Also they can be easily damaged  Is a optical devices Types of DVD’s:  DVD minus R  DVD plus R  DVD minus W  DVD plus W

39. DVD-R and DVD + R  DVD-R can be played on most home DVD player  DVD-R media is at the moment the cheapest most common  Can only be used in DVD Recorders and Burners that support DVD-R recording or multi-format recording  Its rewriteable  Has a 4.7gb DVD disc  The DVD+R disc type does not compare well with DVD-R as far as DVD playback compatibility  They can only be used in DVD Recorders and Burners that support DVD+R

40. Magnetic tape  It’s a magnetic device  It can store large amount if data  Used to backup data  Large organizations use it  It uses serial access to data  Needs a special type of equipment to read or record data  Over 100 GB memory capacity  Its cheaper to store data on them