Courses/Computer Science/CPSC 355.W2014/Lecture Notes/InstrImpl

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Instruction Implementation

Today we examined how these instructions are implemented in terms of logic gates, and how their functional units can form the basis for an implementation of other instructions.

  • AND
  • OR
  • XOR
  • NOT (logical negation, one's complement)
  • NEG (arithmetic negation, two's complement)
  • ADD (a combination of AND, XOR, and OR)


  • Continue discussion of instruction implementation and use.
  • How are INC and DEC implemented? Note that this is a good example of CISC vs. RISC again: e.g., ADD eax, 1 = INC eax
    • INC
    • DEC
  • What are NOT and NEG?
    • NOT
    • NEG
  • difference between arithmetic shift right and logical shift right
  • examine instructions for manipulating binary values as bytes, words, double words, quad words
    • signed vs. unsigned global variables
  • (Integer) Multiplication and division
    • IMUL
    • IDIV