Computer science

Computer science

1. Binary data

   • Bits and bytes
     • Binary numbers are made up of 1 and 0. Binary digit =Bit
     • One bit is the smallest piece of a computer. A bit is an on/off switch.
     • Bits organised in groups of 8, called bytes.
     • if number is less than 8 we add 0s. 1101=00001101
   • Binary and denary
     • Something that is in 10 different forms is denary

2. Data transmission

   • Computers can turn buinary data into on/off that can be transmitted
   • Signals can be: · Electric pulses through metal cables. ·Pulses of light through fibre-optic cable. ·Wirless signals
     • Every system that carries in/off signals are called transmission medium
   • Long or short distance
     • Data transmission links computers, computer can send data. The internet has long distance communication links and data transmission is used in short distances.
     • Different part of computers transmit data to each other. A printer uses data transmission.
   • Simplex and duplex
     • Simplex communication : Signal goes in one direction only.
     • Duplex communication: A two way link, signal goes both ways (phone conversation)
     • Half duplex: Only carry signals in one direction at a time. (Walkie talkie)
   • Types of cables
     • Twisted pair cable: Short distances, in long distances electric interferences causes errors in data
     • Coaxial cable: Protected against electrical interferences, expensive, not flexible.
     • Fibre optic cables:expensive, not affected by electrical interferences, long distance links.
   • Serial transmission

3. Serial or Parallel

   • Serial transmission: Bits send one at a time. Down single wire. Long distances
   • Parallel transmission:Each wire carries 1 bit.

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