Display processing unit for drawing vectors
AssigneeDigital Equipment Corporation
InventorRobert J. Quinn
Life of this patent
Estimating the term…
Abstract
A high speed display processing unit (DPU) for displaying vectors on a cathode ray tube is disclosed. Each vector to be displayed is classified as to whether it is virtual, visible or both. If the displayed vector is partially visible, a digital section of the DPU calculates the length of the visible portion of the vector. Prior to drawing the vector, the digital section determines the major axis of the vector and its tangent. Each of the above values is provided to an analog section of the DPU which then draws at a constant velocity the visible vector. The DPU also includes circuitry for scaling, offset calculations and light pen hits.
Claims16
In a display system for drawing a vector, a display processing unit comprising:
- A. a digital section comprising:
- 1. means for receiving the rectangular coordinates of said vector;
- 2. means for storing the starting position of said vector;
- 3. means responsive to said receiving means and said storing means for determining whether said vector may be drawn by said display system;
- 4. means responsive to said determining means for comparing the length of the rectangular coordinates of said vector to determine which length is greater;
- 5. means responsive to said receiving means and said determining means for calculating the tangent of said vector;
- B. an analog sector comprising:
- 1. means for generating a ramp voltage;
- 2. means responsive to said comparing means for inhibiting said generating means;
- 3. means responsive to said calculating means for altering said ramp voltage from said generating means into separate voltages proportional to the tangent of said vector;
- 4. means responsive to said separate voltages from said altering means and to a voltage responsive to said storing means for combining the magnitude of said voltages;
- and
- 5. display means responsive to said combining means for displaying said vector.
The process of displaying a vector on a display device, said process comprising the steps of:
- A. identifying the location of said vector with respect to the display area;
- B. determining the rectangular coordinates of said vector which are within said display area;
- C. comparing said rectangular coordinates of said vector to determine which is larger;
- D. determining the tangent of said vector;
- and
- E. generating an analog voltage to said display device, said analog voltages being responsive to said vector within said display area.
Dependencies are inferred from the claim text.