Computational Logic

Computational Logic

1. Computer systems store and process data as binary digits (represented as 0s and 1s)

2. The flow of electricity down a single cable or through a switch can be represented in binary as a 1, whereas a cable or switch without electricity flowing through it can be represented as a 0.

3. Transistors

   • Transistors are electrical components made from semiconductor materials that can act as electrically-controlled switches.
     • A common way to think of transistors is that they are like taps. When a tap is turned on, water coming into the tap is allowed to flow through the tap and to come out.
   • In a transistor, when the "base" input on a transistor has a small current flowing through it, the larger current entering the transistor from the "collector" can flow through to the the "emitter".

4. Logic Gates

   • Multiple transistors can be arranged together to form more complex "switches" that only allow electricity to flow through if all or some of the transistors are "on".
   • Such arrangements of transistors are called logic gates - they act like gates that only open if certain logical conditions are met.
   • There are three types of logic gate that you must be familiar with at GCSE - AND, OR and NOT logic gates.

5. And gate

   • AND gates have two inputs and one output
   • An AND gate will only output current (represented as a 1 on the output) if both inputs are on (also represented as 1s)