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Computer Systems

I’m ONLY a machine!. Computer Systems. Standard Grade Revision. 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. Central Processing Unit. CPU. Input.

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Computer Systems

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  1. I’m ONLY a machine! Computer Systems 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 Input Output RAM ROM Backing Storage

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

  5. Units of Storage

  6. Main Memory CPU Input Output RAM ROM Backing Storage

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

  8. 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 Main Memory

  9. CPU Input Output RAM ROM Backing Storage Backing Storage

  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 Media Drive or Media

  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. C 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

  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. Backing Storage Requirements • Different applications need different amounts of storage. • A page of text: • A simple graphic • A high resolution photograph • A song • A video

  20. CPU Input Output RAM ROM Backing Storage Input

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

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

  23. Sound Card • Sound Card • To input sound the sound must be changed from Analogue to digital. • The sound card carries out the conversion process called sampling.

  24. Specialised Input Devices • Voice Recognition • Handwriting recognition • Good for portable systems • OCR • Software used to scan text. • Specialised input devices are especially significant for • disabled users • virtual reality

  25. Mouse Input

  26. CPU Input Output RAM ROM Backing Storage Output

  27. 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 Output Devices - Printers

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

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

  30. C 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

  31. Multimedia Multimedia computers use a wide range of input and output devices to achieve the highest quality.

  32. Types of Computer • Desktop • Laptop/Notebook • Palmtop • Mainframe

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