A computer input device removably mounted to a keyboard is disclosed. A bar, which may be slightly longer than the width of the keyboard, is slidably mounted beneath the keyboard. The bar is slidable from a first position in which one end of the bar extends beyond the side of the keyboard to a second position in which the other end of the bar extends beyond the other side of the keyboard. An input device, such as a trackball, is removably attached, for example, by hook and loop fasteners, to the end of the bar which extends beyond the side of the keyboard. To move the device to the other side of the keyboard, the device is lifted off the end of the bar, the bar is slid under the keyboard until the other end extends beyond the other side of the keyboard, and the device is attached on the other end of the bar. The removable mount of the present invention thus accommodates left and right side mounting, eases the switching from side to side, and takes up minimum space.