Computer control

Abstract

A computer pointing system employs two modes of moving a marker on a computer display in correspondence with movement of a finger-grippable element within a pointer area of movement wherein one of the modes of movement produces a movement of the marker proportional to movement of the finger-grippable element and the second mode produces movement of the marker which is equal to the product of a distance of the marker from an edge of a display area of movement times the quotient of the distance of movement of the finger-grippable element divided by the distance of the finger-grippable element to an edge of the pointer area of movement. The second mode can be called by movement of the finger-grippable element at a rate greater than a predetermined rate or at a position within an outer ring area of the pointer area of movement. Edge regions of the pointer area of movement define macro instruction regions which, when called by an operation of a switch, pass macro instructions to a user program. An index of pages of a file having a plurality of pages can be displayed by selecting an edge region and can be used to select the page to be presented on the display of the user program. Gratings employed in the pointing device are formed by undulations in transparent walls wherein both valleys and hill tops of the undulations define sections of the grating parallel to the movement which are equal to each other and to the component of inclined sidewalls in the direction of movement.