computer

• The progression in hardware representation of a bit of data:
  1. Vacuum Tubes (1950s) - one bit on the size of a thumb;
  2. Transistors (1950s and 1960s) - one bit on the size of a fingernail;
  3. Integrated Circuits (1960s and 70s) - thousands of bits on the size of a hand
  4. Silicon computer chips (1970s and on) - millions of bits on the size of a finger nail.
• The progression of the ease of use of computers:
  1. Almost impossible to use except by very patient geniuses (1950s);
  2. Programmable by highly trained people only (1960s and 1970s);
  3. Useable by just about anyone (1980s and on).