Just a few more notes from Chapter 2

• In the previous section, we saw a circuit with a feedback loop, and a clock circuit with a delay loop.
• We can combine these to build the control circuitry for our three number adding machine.
• 

• Just because they are important, describe an N control line mux.
• We will need a slightly modified version of a simple mux.
• 
• We will use this in the next chapter.
• Using this mux, how could we improve our design to make it more generic?
• We will also need another component, an encoder,and a decoder.
  • A Decoder takes n inputs and produces 2ⁿ outputs.
  • It essentially takes an address as input, places a 1 on the corresponding output line, while changing all other output lines to 0.
  • 

  • i0	i1	o0	o1	o2	o3
    0	0	1	0	0	0
    0	1	0	1	0	0
    1	0	0	0	1	0
    1	1	0	0	0	1

  • Note, these are just the minterms for an n input circuit.
  • We will use this in chapter 3 to construct memory.
  • An encoder works the other way, looks at which line is lit and returns its address.