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Computer Systems

Learn about computer interfaces and how they allow devices to communicate with systems. Explore interface functions such as compensation, data conversion, and temporary storage. Discover various types of interfaces including USB, Firewire, Thunderbolt, and wireless technologies like WiFi and Bluetooth.

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Computer Systems

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  1. Computer Systems Nat 4/5 Computing Science Interfaces

  2. Nat 4/5 Peripherals • How many of you have connected a device (peripheral) to your computer? • USB Flash Drive • Mobile Phone/Ipod? • Printers/Scanners? • You have either connected these using wires or wirelessly. But they have all connected using an interface

  3. Nat 4/5 What is an interface? • An interface can be described as: • Boundary across which two systems communicate • This is the piece of equipment that allows your scanner to communicate with the PC or for the pc to send information to the printer. • The devices may work differently. • It is the interface’s job to enable to devices to work together

  4. Nat 4/5 Interface- Functions

  5. Nat 4/5 Function: Compensation • Compensating for differences in speed between the CPU and peripherals • Compare the processor of a computer and an iPod:- • Computer CPU Speed: 2.5Ghz • IPod CPU Speed: 800Mhz • If the computer tried to get the iPod to do instructions at the same rate as it could there would be a problem!

  6. Nat 4/5 Function: Data Conversion (Analogue and Digital) • Computers use digital signals • 2 values 0 and 1 to represent on and off • A digital signal could look like:- • An analogue signal varies continuously between two limits • Sound, light, temperature are analogue

  7. Examples of Data Conversion Interface carries out digital to analogue conversion Interface carries out analogue to digital

  8. Nat 4/5 More Examples of Data Conversion Digital Analogue Digital Analogue

  9. Function: Data Conversion (Serial and parallel) • Remember that data conversion means “change data from a peripheral so processor can understand it and vice versa” • E.g. change serial data to parallel and vice versa • Serial data transmission • 1 data line that bits go along 1 after another • efficient for long distances

  10. Function: Data Conversion (Serial and parallel) • Parallel data transmission:- • Bits travel simultaneously along different lines • Fast • Suits short distances e.g. processor & peripherals or inside processor

  11. Example of Data Conversion Interface carries out serial to parallel conversion

  12. Nat 4/5 Function: Temporary Storage • The computer can send data to the printer more quickly than the printer can process it • The interface stores data temporarily to free up the processor • The interface sends more data to the printer when the printer is ready

  13. Types of interface : USB 2 • USB = Universal Serial Bus - standardised the connection of devices – many devices use USB • Data transfer rate - 480 Megabits per second • 40 times faster than USB 1 • Used when connecting:- • mouse, keyboard, printer, etc • USB 2 can connect USB 1 devices – transfers data at USB 1 speed

  14. Types of interface : USB 3 • 5 Gbit/s – called Superspeed • 10 times faster than USB 2 • Used when very fast access to data is required e.g • streaming HD movies • making a backing up of an internal hard drive to an external hard drive • USB 3 can connect USB 2 devices – transfers data at USB 2 speed

  15. Types of interface : Firewire 800 • High speed connection • 800 Megabits per second • Similar uses to USB

  16. Types of interface : Thunderbolt 7 SATA • Thunderbolt Version 2 – connects devices to the computer e.g. HD camera, keyboard, printer, etc • 20 GigaBits per second • SATA – connects motherboard to hard drive or optical drive • 6 Gigabits per second

  17. Nat 4/5 General Trends • Transfer Speeds • USB has improved up to USB 3 • 12 Mbs up to 4.8Gbps • SATA is now on revision 3 • 1.5 Gbit/s up to 6Gbit/s • Wireless • Wifi • Bluetooth • Infra Red (IR)

  18. Infrared • Like tv remote control • Needs direct line of sight between transmitter an receiver • Short-range

  19. Bluetooth • Uses radio waves that pass through walls so devices don’t need to point at each other • Temporary short-range link between personal devices e.g. • mobile phones and headsets • Palmtop • Laptop • Range 10m • Speed of data transfer 1 = Megabit per second

  20. WiFi • Wireless Fidelity Alliance • Range 12 – 50 metres • Data transfer rate 5- 12 Megabits per second • Used by wireless networks in homes

  21. Summary A device needs an interfaceto allow it to communicate with a system An interface has three main functions Nat 4/5

  22. Summary - continued • There are many types of interface:- • USB 2, 3 • Firewire • Thunderbolt • SATA • Wireless:- • WiFi • Bluetooth • Infrared

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