Section 7.7
Review Questions
The structure of the control unit
  1. What does DFA stand for?
answer...
Deterministic Finite Automaton
  1. In DFAs, nodes represent _____________________ and arcs represent _____________________.
answer...
nodes represent states, arcs represent inputs or conditions that change states
  1. How many arcs can come out of any one node?
answer...
any number
  1. What circuit or component does a DFA simplify?
answer...
the control unit, the part of the computer that drives the control points
  1. Label the control DFA for the CSC-1 with the phases of the instruction cycle. The execute phase is shown for you already. 
               Execute
               Fetch instruction from memory
               Start cycle; copy PC into MAR
               Operand fetch
               Save instruction into IR register
answer...
  1. Why must the operation decoder take in the first 8 bits of the IR register? Why not just the first four, since that is where the opcode is?
answer...
because some of the instructions have opcodes that are 8 bits long (those whose top 4 bits are 1111)
  1. Which circuit or component keeps the control unit moving from one state to the next on a regular basis?
answer...
the clock
  1. What does Hz stand for?
answer...
Hertz, one cycle
  1. What does 120 MHz mean?
answer...
120 million cycles per second