Multi-screen display control system and its method

• US 4,914,607 A
• Filed: 04/08/1987
• Issued: 04/03/1990
• Est. Priority Date: 04/09/1986
• Status: Expired due to Term

• Current Assignee: Hitachi, Ltd.
• Original Assignee: Hitachi, Ltd.
• Inventors: Yamada, Kimitoshi, Takanashi, Katsuya
• Primary Examiner(s): Harkcom, Gary V.
• Assistant Examiner(s): HERNDON, HEATHER R
• Application Number:
  US07/035,982
• Time in Patent Office: 1,091 Days
• Field of Search: 364/518, 364/521, 340/721, 340/724, 340/798-800, 382/44-47
• US Class Current: 715/790
• CPC Class Codes: G09G 5/14 Display of multiple viewports

Abstract

In a transfer data screen buffer added to a multi-window display, a command stream for displaying segments to be displayed and superposed over the multi-window display is stored. By the execution of the command stream, the display data developed into a bit map undergoes exclusive OR operation bit by bit with the bit-map developed data of the multi-window data. The operation result is fed back to the display screen bit map memory to be displayed.

Claims

1. A display control apparatus for simultaneously displaying portions of a plurality of virtual data windows on a display comprising:

(a) a first screen memory for storing a part of the data of virtual data windows in such a form that the data for only one virtual data window will be displayed for a region where more than one window overlaps on the display;

(b) a second screen memory for storing additional data to be displayed;

(c) means for writing the data of said second screen memory into the first screen memory so that the data of the first screen memory changes logical state when the second screen memory data is written;

(d) means for generating a display command stream from one of several types of display directives inputted to said display control apparatus;

(e) first buffer means for holding a first generated display command stream from a first type of display directive;

(f) second buffer means for holding a second generated display command stream from a second type of display directive;

(g) means for executing the display command stream held in said first buffer means to form the display data for said first screen memory, and for executing the display command stream held in said second buffer means to form the display data for said second screen memory; and

(h) said writing means including an exclusive OR operation with respect to data from said first and second memory screens and for supplying the exclusive OR operation result to said first screen memory.

2. A display control system comprising:

a display screen;

a means for storing data to be displayed upon the display screen;

a means for writing the data to be displayed into the storing means;

a means for generating writing commands for the writing means, the commands contain the data to be stored, the address where the data is to be stored in the storing means and a priority for the data to be stored whereby the writing means selectively writes the data into the storing means in a predetermined correspondence with the data priority administering a display of multiple data windows on the display screen;

a second means for generating writing commands for the writing means which contain a second data to be stored and the address where the data is to be stored in the storing means; and

a means for inserting the second data from the second generated writing commands into the storing means so that the data previously stored at the address in the storing means changes logic state whereby a graphic element is imposed upon the display screen irrespective of the multiple data windows formed by the priorities of the first generated commands, wherein said inserting means comprises exclusive OR operation between data in the storing means at the address contained in the second generated writing command and data contained in the second generated writing command.

3. The display control system as defined in claim 2 wherein the graphic element comprises a graphic character.