United States Patent [19] [ii] Patent Number: 4,559,533
Bass et al. [45] Date of Patent: Dec. 17, 1985
[54] METHOD OF ELECTRONICALLY MOVING PORTIONS OF SEVERAL DIFFERENT IMAGES ON A CRT SCREEN
[75] Inventors: Leland J. Bass; Roy F. Quick, Jr., both of San Diego; Ashwin V. Shah, Encinitas; Ralph O. Wickwire, San Diego, all of Calif.
[73] Assignee: Burroughs Corporation, Detroit,
Mich.
[21] Appl. No.: 548,551
[22] Filed: Nov. 3, 1983
[51] Int. CI.4 G09G 1/00
[52] U.S. CI 340/724; 340/721;
340/747; 340/750
[58] Field of Search 340/724, 747, 748, 750,
340/721
[56] References Cited
U.S. PATENT DOCUMENTS
4,197,590 4/1980 Sukonick et al 340/731 X
. 4,200,869 4/1980 Murayama et al 340/709 X
4,414,628 11/1983 Ahuja et al 340/721 X
4,439,760 3/1984 Fleming 340/747 X
4,470,042 9/1984 Barnicia et al 340/721 X
4,484,187 11/1984 Brown et al 340/721 X
A method of electronically moving portions of several different images on a CRT screen includes the steps of: storing a first image in one section of an image memory, and storing a second image in a different section of the image memory; storing control bits in a control memory which define high and low priority viewports on the screen and correlate portions of the first and second images to the high and low priority viewports respectively; displaying, in response to the stored control bits, the entire portion of the image in the high priority viewport and only the non-overlapping portion of the image in the low priority viewport by transferring the image portions from the image memory to the screen with no frame buffer therebetween; modifying at least some of the stored control bits to change the priorities of the high and low priority viewports to low and high respectively; and repeating the displaying step, in response to the modified control bits, to display the entire portion of the image in the new high priority viewport and only the non-overlapping portion of the image in the new low priority viewport.
