Computer Hardware

1. Computer Hardware

2. Backing Storage Devices

3. Input Devices

4. Output Devices

5. Hardwareand Software • Hardware refers to all the parts of the Computer System that we can touch. Examples of hardware are monitors, joysticks, printers, processors etc. • Software refers to all the programs and data that we use with the computer.

6. What is a Computer? • A computer is an information processing machine. • A computer only follows the instructions it is given. • Data is Input, Processed and then Output. I’m ONLY a machine!

7. Sizes of Computers Smallest • Microprocessor • A small chip programmed with instructions. • Microcomputer • The most common type of computer. The IBM PC is a microcomputer • Mini Computer • Medium to Large computers - mainly used to process business information. • Mainframe Computer • Very powerful computers able to process 1000’s of times more information a second than PCs Biggest

8. IPO -Input, Process, Output INPUT PROCESS OUTPUT Data is INPUT into the computer system It is then PROCESSED to produce useful Information as OUTPUT.

9. Data and Information Data has no meaning • Data is made up of symbols e.g. 871652; H789 IOS; £76.91 Information has a meaning • We understand what a piece of information is about e.g Telephone Number: 871652 Car License Plate: H789 IOS

10. INPUT OUTPUT PROCESS More Input, Process, Output • Data is the RAW MATERIAL. • This raw material is processed. • When the processing is completed a useful thing is produced…INFORMATION

11. Input Central Processing Output Devices Unit (CPU) Devices Backing Storage Devices Computer - Block Diagram • The Computer System consists of four parts. Input, Processor [CPU], Output, Backing Storage

12. The central processing unit (CPU) This is the part of the computer where the searching and sorting of data, calculating and decision-making goes on. The CPU contains the processor [Control Unit and the Arithmetic and Logic Unit (ALU)] and the Main Memory

13. The Processor • The CONTROL UNIT fetches program instructions from the memory storage locations, decodes and then executes them. • The ALU (Arithmetic/Logic Unit) carries out all the calculations as instructed by the control unit.

14. ROM RAM Data Flow PROCESSOR MAIN MEMORY - ROM and RAM • ROM is Read Only Memory • Data stored in ROM can only be read, it can never be written over or deleted. We normally store important programs in ROM to do with the computers Operating System (see later).NON VOLATILE MEMORY • RAM is Random Access Memory • It can be written to and read from. It is where most programs and data are stored while the computer is being used. RAM loses its contents when the computer is switched off.VOLATILE MEMORY

15. Memory • Computers store blocks of data called‘words’ in memory (A 32 bit computer has words that are 32 bits long). • Each place that can store a word is called astorage location. • Each storage location has a uniqueaddressthat identifies it from all the other locations.

16. Machine Code • Computers only understand binary!!! • All programs have to end up in binary language in order work. • The binary language that the computer understands is calledMACHINE CODE • Machine code looks like this… 00100111,01110100,10010001

17. Bits and Bytes [BINARY] • Each 1 or 0 is called aBIT(short for Binary Digit). • Eight bits are called aBYTE. • 1024 bytes is aKILOBYTE (Kb for short) • 1024 kilobytes is aMEGABYTE (Mb for short) • 1024 megabytes is aGIGABYTE (Gb for short) These units are used to measure the size of storage or storage requirements e.g. the available memory, hard disk space, program size.

18. Bits and Bytes [BINARY]

19. Binary Everywhere! • Binary is used to store all the data and programs in a computer system. • We use binary to store: Graphics, Text, Numbers,Video, Sound andPrograms. • Binary is just the code used to store the data.

20. Storing Numbers • Numbers are stored in binary. 1Bin is 1Dec 10Bin is2Dec 1000Bin is 8Dec 1001Bin is 9Dec 1111Binis 15Dec 11111111Binis 255Dec • You don’t need to understand binary(that’s Maths) but you do need to know that it is how most numbers are stored in the computer.

21. Storing Text • Text is stored using a special set of codes called ASCII. • Each symbol (letter, number etc) has its own unique code e.g. • ais 97,Ais 65,?is 63,3is 51 • ASCII (AmericanStandardCode forInformationInterchange) • One ASCII code is one byte long (eight bits).

22. 1 0 0 0 0 0 0 1 1 0 1 0 0 1 0 1 1 0 1 0 0 1 0 1 0 0 0 0 0 0 0 0 0 0 0 1 1 0 0 0 0 1 0 0 0 0 1 0 0 1 1 1 1 1 1 0 0 1 1 1 1 1 1 0 Storing Graphics • Black and White graphics are stored using pixels (Picture Elements). • The image to be stored is broken up into dots, each dot is a pixel. • The pixels are ON for black and OFF for white e.g.

23. Hardware Devices

24. Hardware Devices • Devices are eitherINPUT,OUTPUTorBACKING STORAGE. • Input devices allow us to enter data into the computer system(mouse, microphone etc). • Output devices allow us to receive information from the computer system(monitor, speakers, robot). • Backing storage devices allow us to store programs and data so that we can use them later(floppy disc, magnetic tape, CD-ROM).

25. Backing Storage Devices

26. Backing Storage Devices • Backing storage is used to store programs and data when they are not being used or when a computer is switched off. • When programs and data are needed they are copied into main memory but also still remain on backing storage. • Magnetic tape drives, floppy disk drives and hard disk drives are all examples of backing storage devices.

27. Backing Storage Devices ? Magnetic tape, floppy disc, hard disc and CD-ROM are all types of backing storage. • WORM - Write Once Read Many A WORM is a writable optical disc. An optical disc is any disc that can be read using light (normally laser light). WORM drives use a high powered laser to burn the data into the disc. This can then be read in the same way that CD-ROM's are read. Because the data is burnt onto the disc each disc can only be written once and the data written is permanent.

28. PROM and EPROM • PROM and EPROMare both special types of programmable read only memory. • PROM stands for Programmable Read Only Memory. This type of memory can be programmed once but can’t be changed again afterwards. • EPROM stands for Erasable Programmable Read Only Memory. This type of memory can be programmed and then changed whenever necessary.

29. The Floppy Disk Write Protect Tab Disc Label • Afloppy disccan be used to save data. • It can also be used to make a backup copy ofsmallfiles. • Abackup is asecondcopy of your data that you take in case something happens to the original. • You shouldalwaysmake a backup of important files. • Size : 3.5 inch • Capacity : 1.44 Mb

30. Formatting A Floppy Disk The formatting process involves: • Dividing the surface of the disk into invisible circles called tracks and sectors. • Setting up a root directory where the list of files that are on the disk will be kept. • Data on a magnetic disk is located by finding the address of its location from an index in the root directory. • Each address in the index contains a track and sector number for an individual data segment.

31. Tracks Sector Index Formatting A Floppy Disk No data is stored on the outside or inside tracks of the disk

32. The Hard Disc and Drive • A hard disk is a circular metal disk coated with magnetic material and usually sealed in a hard disk drive inside the computer. • Some hard disk drives are not permanently fixed inside the computer but are removable. • Data stored on a hard disk can be accessed much more quickly than data stored on a floppy disk. • Hard disks can store much more data than a floppy disk. A typical hard disk inside a personal computer can hold many gigabytes of data.

33. The Hard Disc and Drive

34. Non-magnetic storage • Non-magnetic storage involves the use of media not coated in magnetic material. • Examples of this are: CD-ROM, Video Disc, Digital Video Disc (DVD) and WORM. • These use pits and bumps (lands) on the disc to store digital data and use laser light to write and read them.

35. = 445 floppy discs 1 CD-ROM Capacity • The size of memory, hard disc space, floppy drive space, programs, data files etc. are all measured by the number of bytes, kilobytes, megabytes orgigabytes(1024 megabytes)of data they contain.

36. File compression • File compression softwarecan be used to make files smaller so that more data can be stored in the same amount of space on backing store. • When a compressed file on backing store needs to be used it must be decompressed. • This can be done using decompression softwareor by setting files up to be self-extracting which means that they can automatically decompress themselves. • Winzipis an example of software that can be used to compress and decompress files.

37. Types of Access • There are two types of access • Random Access(also calledDirect Access)devices retrieve the data you want straight away e.g. CD-ROM drive, Hard disc drive, floppy disc drive. • Sequential(also calledSerial) devices have to move through all the data, record after record, to find the data you need e.g. Cassette tape, magnetic tape.

38. Types of access • Random Access • Refers to the ability to access data at random. In a random-access system, you can jump directly to file Z. • Sequential Access • To go from file A to file Z in a sequential-access system, you must pass through all intervening files. • Sequential access is sometimes called serial access.

39. Input Devices

40. Types of Input • Keyboard Most keyboards are of the QWERTY type but not always. They have always been used for inputting data to the computer • Mouse The mouse is very important in WIMP systems and is used to move a pointer around the screen and make selections by pressing a button

41. Advanced types of Input • Trackball A trackball is basically an upside down mouse. A trackball allows the user to move a small ball in order to move the pointer across the screen. • Graphics Tablet A graphics tablet allows the user to draw on a special worktop. As the user draws the details are stored on the computer system. These devices are most often used by architects and designers.

42. Joystick • The main use of a joystick is to play computer games by controlling the way that something moves on the screen. • Joysticks can be used to control movement from side-to-side, up-and-down and diagonally. • A joystick will also always have at least one button on it which can be used to make something happen like making a character in a game jump or a gun fire.

43. Touch Screen A touch screen can detect exactly where, on its surface it has been touched. Touch screens are used in a lot of fast food chains and restaurants because they are easy to keep clean and re-program if changes need to be made to the menu.

44. Digital Camera • A digital camera can store many more pictures than an ordinary camera. • Pictures taken using a digital camera are stored inside its memory and can be transferred to a computer by connecting the camera to it. • A digital camera takes pictures by converting the light passing through the lens at the front into a digital image.

45. Scanner • A scanner can be used to input pictures and text into a computer. • There are two main types of scanner; Hand-held and Flat-bed.

46. Voice Recognition With voice recognition systems the computer can understand the words spoken to it and can carry out commands associated with the words. Using voice recognition a letter can be dictated instead of being typed at the keyboard. • Handwriting Recognition Handwriting can be recognised and the computer can convert the written text into typed text for storing.

47. Optical Character Recognition • OCR Is used to convert paper typed documents into text files that can be edited and stored on a computer system. OCR software can search a scanned image for the shapes of letters, numbers etc. When it finds shapes that match it converts them to the correct text and stores them in a file.

48. Output Devices

49. Types of Output • Plotter A plotter is a device used for creating a hard copy of the output from a computer system. Plotters use special pens to draw the output as a series of lines. Plotters are often used to output building drawings and designs. • VDU or Monitor Visual Display Unit (VDU) is the proper name for the computer monitor. The VDU allows us to see the output from the computer.

50. Monitor - Visual Display Unit • A monitor or VDU is an output device that can display graphics and text and video. • The picture on a monitor is made up of thousands of tiny coloured dots called pixels. • The quality of the output on a monitor depends on its resolution. • The resolution of a monitor depends on the number of pixels that it can display.