Multi-screen display control system and its method

Claim 2

A display control system comprising: a display (15) having multiple windows for simultaneously displaying a plurality of logical terminals; a screen buffer (6) for storing therein data to be displayed on said display; and a logical plane (77) disposed at the highest rank layer of a display section of the multiple windows so as to surpass respective windows, data of respective windows and data of said logical plane being subject to operation and stored in said logical plane.

Claim 3

A display control system according to Claim 1, wherein said operation comprises exclusive OR operation (78) between data of respective windows and data of said logical plane.

Claim 4

A display control system according to Claim 2, wherein said screen buffer comprises a command stream buffer (137) for displaying said multiple windows and a second command stream buffer for displaying said logical plane, wherein each of said data is picture element data obtained on the bit map by executing said command stream, and wherein said display control system carries out said logical sum operation for picture element data existing on said bit map bit by bit and comprises means for feeding back the resultant sum to said logical plane.

Claim 5

A display control apparatus for simultaneously displaying portions of a plurality of virtual display terminals (3) on one display (15) comprising: (a) a first screen memory (6) for storing a part of data of said virtual display terminal to be displayed, in such a form that the data will be cut and fit in mutually and for supplying the data to said display; (b) a second screen memory (77) for storing additional data to be displayed together with the contents displayed on said first screen; (c) means (78) for receiving the data of said first and second screen memories and for carrying out logical operation between them; and (d) pass means (79) for receiving the result of said logical operation and supplying it to said first screen memory.

Claim 6

A display control apparatus for simultaneously displaying portions of a plurality of virtual display terminals (3) on one display (15) comprising: (a) a first screen memory (6) for storing a part of data of said virtual display terminal to be displayed, in such a form that the data will be cut and fit in mutually and for supplying the data to said display; (b) a second screen memory (77) for storing additional data to be displayed together with the contents displayed on said first screen; (c) means (78) for receiving the data of said first and second screen memories and for carrying out logical operation between them; and (d) pass means (79) for receiving the result of said logical operation and supplying it to said first screen memory.

Claim 7

A display control apparatus according to Claim 4, further comprising: means (9, 10, 11, 12) for generating a display command stream in obedience to a display directive inputted to said display control apparatus; first buffer means (13) for holding a stream supplied to said first screen memory among said stream on the basis of said display directive; second buffer means (137) for holding a stream supplied to said second screen memory among said stream on the basis of an additional display directive; means for executing the display command stream held in said first means to develop the display data in the bit map form on said first screen memory, and for executing the display command stream held in said second means to develop the display data in the bit map form on said second screen memory; and said developing means including means for carrying out exclusive OR operation bit by bit with respect to bit map developed data on said first and second screens and for supplying the operation result to said first screen memory.

Claim 8

A display control apparatus according to Claim 5, further comprising: means for executing the display command stream held in said second means again on the basis of directive for updating or deleting said additional display directive supplied to said display control apparatus and for erasing a portion of contents displayed on said first screen memory based upon said additional display directive.

Claim 9

A display control apparatus according to Claim 4, wherein said first and second screen memories respectively includes portions for storing color component bits for color display, and said display control apparatus includes means for applying logical operation to each of said color component bits stored on said first and second screen memories.

Claim 10

In a multi-screen system including a display tube (15), memories (23, 13, 137) for storing data to be displayed on the display tube, and a plurality of virtual screen memories (3), portions of display data elements held in said virtual screen memories being displayed on said display tube while being overlapped, a method for displaying an additional display element over said overlapped display comprising the steps of: (a) applying exclusive OR operation bit by bit to said overlapped data and said display element data; and (b) feeding back the result of said exclusive OR operation to said display data storage memory to display the result on said display tube.

Claim 11

In a multi-screen system including a display tube (15), memories (23, 13, 137) for storing data to be displayed on the display tube, and a plurality of virtual screen memories (3), portions of display data elements held in said virtual screen memories being displayed on said display tube while being overlapped, a method for displaying an additional display element over said overlapped display comprising the steps of: (a) applying exclusive OR operation bit by bit to said overlapped data and said display element data; and (b) feeding back the result of said exclusive OR operation to said display data storage memory to display the result on said display tube.

Claim 12

A method according to Claim 8, comprising the steps of: carrying out exclusive OR operation with respect to the result of said exclusive OR operation and said additional display element and feeding back the result to said display data storage memory, in response to a directive request for changing said additional delay element; and replacing the display element by said additional display element on the basis of the directive for changing the display and carrying out exclusive OR operation with respect to said additional display element and said overlapped data.