Lectures
Valence Rings
Transistors
Boolean Tables

Digital binary computing uses 0 and 1.
  
   Fluid to transmit information.
   Switch to store or select transmission path.

Switches
  As memory
    On/Off - 1 bit. Memory

  For decision making
    Simplest logic

    AND - both switches on.  

    OR - either switch on.

    NOT - invert the bit or signal.
   
  Mechanical force
   - commonly decimal, old fashion calculators, cash registers.
   - but check out Domino Computer in wikipedia

  Pneumatic - air
  Hydraulic  - liquids

  Electrical-mechanical
    Relays - electrically tripped but also mechanical.
      Faster than purely mechanical.
     
      Slower than electronic.

      Power intense. 

      Physically large.

  Electronics - fast.
    Vacuum tubes - sometimes referred to as valves.
      Physically large, 

      High voltage, and high power consumption.

      Relatively easy to make.

      Fast

    Transistors.
      Small, 

      Cheap, 

      Small voltage and power draw.

      Technology to make transistors very advanced, expensive initially.

Valence Rings