Computing

Computing

1. Logic gates

   • The output is always the opposite of the input. The output is only ever 1 when the input is 0.
   • Both of the inputs have to be 1 for the output to be one.
   • The output is only 1 when either of the inputs are 1. There is only ever a 0 when both of the inputs are 0.
   • AND GATE
   • OR GATE
   • NOT GATE

2. Why do computers use binary?

   • It is the universal computer language
   • It is a definite yes or no
   • There can be no maybes
   • Has a charge or no charge - so logic gates turn them off or on

3. Fetch De-execute cycle

   • The CPU fetches the data from the RAM
   • Decode the data so that the ALU can understand the binary code, each CPU has a set of instructions which can understand the binary in different ways.
   • The computer then carries out the process and resets the ALU and CPU for the next cycle

4. Storage Devices

   • Flash
     • Non-volatile
     • No moving parts
     • Solid state
     • Universal serial bus - USB
   • Magnetic
     • Non-Volatile
     • All data is deleted when the power to the storage device is stopped
     • Large storage capacity
     • RAM (Random Access Memory)
   • Optical
     • Non-volatile
     • Is read by a laser
     • DVD

5. Input and Output devices

   • Input devices allow information to go into the computer
     • EG/ Keyboard
   • Output devices allow information to be displayed to humans
     • EG/ Monitor

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