1. Computer Systems I’m ONLY a machine! Standard Grade Revision

2. Hardware Hardware refers to all the parts of the Computer System that we can touch. An item of hardware is called a device. Microprocessor Main memory Input / Output Backing Storage

3. Central Processing Unit CPU RAM Backing Storage Input Output ROM

4. The Processor Carries out the actual process Follows a set of instructions called a program

5. Units of Storage Binary UnitValue Bit1 or 0 Byte8 bits Kilobyte (KB)1024 bytes Megabyte (MB)1024 Kilobytes Gigabyte (GB)1024 Megabytes Terabyte (TB)1024 Gigabytes

6. Main Memory CPU RAM Backing Storage Input Output ROM

7. Main Memory Where the computer stores programs & data Types: –RAM Random Access Memory –ROM Read Only Memory

8. Main Memory RAM Chip –Temporary storage –Data is lost when computer switched off –Data can be written to RAM ROM Chip –Permanent storage –Data is safe when computer is switched off –Data can not be written to ROM

9. Backing Storage CPU RAM Backing Storage Input Output ROM

10. Backing Storage Method used to physically store data. Constantly increasing in capacity to meet demands. Magnetic Storage –Floppy disc, Hard Disc, Magnetic Tape Optical Storage –CD, DVD Solid State –USB Flash Drive

11. Drive or Media DriveMedia

12. Magnetic Storage Hard Disk Drive –Usually main type of backing store –Non-removable media Floppy Disk –Plastic disk with rectangular cover –Removable media Magnetic Tape –Sequential Access –Think VHS tape –Removable media

13. Optical Storage

14. Optical Storage CD-ROM –Read by a laser beam that reflects of surface “pits” and “lands” DVD-ROM –Similar to CD but with larger capacity because of multiple layers CD-Recordable (CD-R) / DVD-R –Write Once, Read Many CD-Rewritable (CD-RW) / DVD-RW –Still uses a laser but contents can be changed

15. USB Flash Drive Universal Serial Bus: –Computer interface used by different devices. Solid State Memory –No moving parts Advantages –Portable –Can have large memory (currently 8GB) –Difficult to damage

16. Access Types Random/Direct Access –Retrieves the data you want straight away. CD-ROM drive, Hard disc drive, Floppy disc drive. Sequential Access –Move through record after record to find the data you want. Magnetic tape C

17. 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 or gigabytes (1024 megabytes) they can store. 500 floppy discs = 1 CD-ROM

18. Comparison of Backing Storage Speed (Data Transfer) CD-R = 32x (4.6Mb Per Second) Flash Drive = USB 2.0 (12Mbps) Capacity CD-R = 750Mb Flash Drive = 128Mb – 8Gb Cost CD-R = Drive - £20 / Discs – 50p Flash Drive = £52

19. Input CPU RAM Backing Storage Input Output ROM

20. Input Devices (Navigational) Mouse Trackball Track pad Touch Screen Joystick SmartBoard

21. Input Devices (Data Input) Keyboard Graphics Tablet Scanner Digital Still camera Digital Video Camera Webcam Microphone

22. Specialised Input Devices Voice Recognition Handwriting recognition –Good for portable systems OCR –Software used to scan text. Sound Card –To input sound the sound must be changed from Analogue to digital. –The sound card carries out the conversion process called sampling. C

23. Mouse Input

24. Output CPU RAM Backing Storage Input Output ROM

25. Output Devices - Printers Laser –Fast 18 Pages Per Min (PPM) –High quality –Expensive –Colour is out of most peoples price range Inkjet –Slower than laser 2-5 Pages Per Min (PPM) –Reasonable quality –Cheap –Most do colour as standard

26. Output Devices Comparison of Printers Resolution –Dots Per Inch (DPI) Speed –Pages Per Minute (PPM) Cost –Capital Cost –Running Costs

27. Output Devices Plotter Monitor (VDU) LCD –Liquid Crystal Display TFT –Thin Film Transistor Multimedia Projector Speakers

28. Output Devices Graphics Card –A device which controls the quality of output on a monitor Sound Card –To output sound it must be changed from digital to analogue –The sound card caries out the conversion process called sampling C

29. Types of Computer Desktop Laptop/Notebook Palmtop