The ornamental design for an arithmetic and controlunit, as shown and described.
FIG. 1 is a perspective view of front, top and right side of an arithmetic and control unit showing our new design;
FIG. 2 is a front view thereof;
FIG. 3 is a rear view thereof;
FIG. 4 is a left side view thereof;
FIG. 5 is a right side view thereof;
FIG. 6 is a top view thereof; and,
FIG. 7 is a bottom view thereof.
The broken lines shown are included for the purpose of illustrating the unclaimed portions of an arithmetic and control unit and form no part of the claimed design.