FIG. 1 is a front elevational view of a first embodiment of an arithmetic and control unit showing my new design;
FIG. 2 is a top plan view thereof;
FIG. 3 is a right side elevational view thereof;
FIG. 4 is a rear elevational view thereof;
FIG. 5 is a bottom plan view thereof;
FIG. 6 is a left side elevational view thereof; and
FIG. 7 is another top plan view thereof wherein the disc tray portion is in the open position, it being shown in broken lines in the drawings for environmental purposes only and forms no part of the claimed design;
FIG. 8 is a front elevational view of a second embodiment of an arithmetic and control unit showing my new design;
FIG. 9 is a top plan view thereof;
FIG. 10 is a right side elevational view thereof;
FIG. 11 is a rear elevational view thereof;
FIG. 12 is a bottom plan view thereof;
FIG. 13 is a left side elevational view thereof; and,
FIG. 14 is another top plan view thereof wherein the disc tray portion is in the open position, it being shown in broken lines in the drawings for environmental purposes only and forms no part of the claimed design.