Ch2 - Morse code

• it is the combinination of dot and dash like binary code in computer.
• the more dash and dot, the more ability to defined the character, which the number is the power of 2(2^{number of dash and dot}). It is just like binanry number. Ch3 - Braille
• it's the sophisticated algorithm that use 6 dot emboss on the paper to reproduce the writing system.
  • It also uses the precedence(or shift code) for number, capital indicator(or escape code) to make this system a lot versatiles.

Ch4 - Anatomy of a flashlight

• V=IR
• The high conduction element are those that have only one outer electron such as Cu, Ag, Au.
• the wider diameter the more easier for electron to transfer = less resistant
• Transferring electrons lose some energy as heat, the more resistance, the more heat produced.

Ch5 - Communicating around the corner

• We can use the earth as an unlimited electron supply(absorb or provide), it's called "connect to earth or ground".
• The longer the wire the higher resistance.

Ch6 - Logic with Switches

• AND == Series connection in the electric circuit
• OR == Parallel connection in the electric circuit

Ch7 Telegraph and relay

• Telegraph is the first device in human history that use electricity and electromagnetic to transfer data.
• Relay can repeat the telegraph with new electricity source so that the data signal is renewed.

Ch8 Relay and gate

• Relays can be connected together either in series form or parallel form, and they will work like Logic gate in circuits. However, they are connected in the metal bar part, not the electromagnetic part. For the electromagnetic parts, they are connected with outer switches.
  • Series form = AND
  • Parallel form = OR
  • connected the going out wire with upper plate = Inverter
• There is 6 types of relay: buffer, inverter, and, or, nand, nor

Ch9 Our ten digit

Ch10 Alternative 10s

Ch11 Bit by Bit by bit

• UPC(universal product code)/Barcode contains 101, 101 as the left and right hand guard patterns and 01010 for center guard pattern
  • the 6 left side code pattern is 0 _ _ _ _ _ _ 1, the 6 right side code pattern is 1 _ _ _ _ _ _ 0
    • There will be only 2 groups of 1 and 0 in each particular code, which means there will be only 2 vertical line(bold and thin line) for each number interpretation
    • For the left side, they all have odd number of 1 bits. For the right side, they all have even number of 1 bits.
  • Semantical rules 0 51000 01251 7
    • The first digit is the number system character eg. 0 = regular UPC, 2 = variable weight grocery items, 5 = coupon
    • The left group(left 5 digit) is the manufacturer code eg. 51000 = the Cambell Soup Company
    • The right group(right 5 digit) is the particular product of company eg. 01251 = 10 ¾-ounce can of Chicken Noodle Soup
    • The last digit is the modulo check character which is calculated by
      1. sum of all odd digit x3 + sum of all even digit
      2. Bring the summation