The ornamental design for a computer having a door, as shown and described.
FIG. 1 is a front perspective view of the design for the computer having the door, wherein the door is illustrated in a closed or latched position with respect to a chassis of the computer, and a handle extends lengthwise along a side portion of the door between top and bottom portions of the door;
FIG. 2 is a front view of the design for the computer having a door as illustrated in FIG. 1;
FIG. 3 is a left side elevational view of the design for the computer having the door as illustrated in FIG. 1;
FIG. 4 is a top side elevational view of the design for the computer having the door as illustrated in FIG. 1, wherein the bottom side elevational view is substantially the same as the illustrated top side; and,
FIG. 5 is a front perspective view of the design for the computer having the door as illustrated in FIG. 1, wherein the door is illustrated in an open or unlatched position rotated partially away from the chassis of the computer.
In these drawings, the solid lines illustrate the claimed ornamental design, whereas the broken lines illustrate environmental features that form no part of the claimed ornamental design.