326 Chapter Thirteen
0 0 0 0 0 0 0 0 0 0 0 1 0 1 0 10 0 0 0 0 0 0 0 0 0 1 0 1 0 1 0•••••••••Rotate Left0 0 0 0 0 0 0 0 0 0 0 1 0 1 0 11 0 0 0 0 0 0 0 0 0 0 0 1 0 1 0•••••••••Rotate RightFigure 13-11
Rotate Operations.
The shland shrselections perform shift left and shift right operations,
respectively. The rotland rotrselections perform rotate left and rotate
right operations, respectively.Trireg
The last component of the CPU is the tristate register component,trireg.
The tristate register is connected to the main data bus and can store
information from the data bus as well as drive information to the data
bus. The triregentity has four ports as shown in Figure 13-12.
Input ais the data input to the register, and port qis the data output
from the register. Input clkis used to store a new value into the register.