Section 7.6: Example of control points and the fetch/decode/execute cycle (Frame 8)                     [prev][home][next]

  1. The value in IR is broken down by the opcode decoder, which sees that 0011 (the first 4 bits) are the ADD instruction. It "knows" that the last 12 bits are then the operand address so it will set up the wires to fetch the value. The decoder causes the ADD wire to go high. This is the operation decode stage.