Rockwell International Corporation

Ronald L Swanson

Lyle R Strathman

Robert A Bolin

Vincent B Collins

A system and technique is disclosed which enables a reduction in memory for the display of superimposed data (alpha-numerics, symbols and graphics) in an all-raster scanned display. A video signal containing information to be displayed on a video monitor by raster scanning techniques is multiplexed with the output of a storage device containing information representing data for controlling the intensity of specific points on the monitor during the raster scan. The intensity is controlled by the signals from memory to produce data on the video monitor as an overlay to the normal video display produced by the video signal. In one embodiment, the storage device is formed by two separate memory areas having a size substantially less than the total number of lines forming one raster field of the video display. The first memory area is multiplexed with the video signal while the second memory area is being filled and the second memory area is multiplexed with the video signal while the first memory area is being filled. This process is repeated a predetermined number of times for each field scan of the video display.

Reduced memory graphics-to-raster scan converter

A system for generating respective X and Y beam deflection command signals as respective running binary counts in X and Y deflection counters utilizing digital computations based on the straight line expressions Y=X tan .alpha., where .alpha. is the line slope. Relative clock rates are defined by the tan .alpha. relationship therebetween, and, by defining a line as lying in one of eight 45.degree. octants, and a circle as successive points of tangency of a plurality of lines tangent to the circle comprising circumferential segments in eight contiguous ones of the octants, the system effects generation of respective X and Y counts to trace a line of selected length and slope as well as a circle of selected radius utilizing but a single table of tangents for angles between 0.degree. and 45.degree. as the required data storage.

Circle/graphics CRT deflection generation using digital techniques

A digital oscillator with output frequency accurately changeable from one period to the next. A plurality of retriggerable monostable multivibrators having discretely different design pulse widths are OR'd to an output monostable multivibrator having the narrowest design pulse width. The plurality of monostable multivibrators are triggered in common by the OR'd outputs thereof such that the longest pulse width one thereof defines the period of the output monostable multivibrator. Logic enabling means permit selection of multivibrator outputs to be OR'd.

Growing community of inventors

Cedar Rapids, IA, United States of America

Ronald L Swanson