Fast Position Controller for a Directed Beam Display
Original Publication Date: 1983-Nov-01
Included in the Prior Art Database: 2005-Feb-07
The Fast Position Controller behaves as an up/down counter driving a digital-to-analog converter. The output is then used to drive the X or Y inputs of a directed beam display, such as the IBM 3251. The effective beam writing speed is limited by the maximum count rate, together with the need for high resolution, in order to minimize &staircase& effects. Using a conventional counter, running at about 25 megahertz, would result in a limiting beam writing rate of 75,000 inches/second for a 12" x 12" picture with 4K resolution. Using the counter described in this article the maximum beam writing speed can be extended to 1,000,000 inches/second at a comparatively modest clock rate of 21.33 megahertz.