公开(公告)号：DE3377683D1

公开(公告)日：1988-09-15

申请号：DE3377683

申请日：1983-12-19

Applicant: IBM

Inventor： IMPEY ALAN A ,  POWELL COLIN V ,  SIMMONS JOHN ,  EASTON COLIN J

IPC: G09G5/377 ,  G06F3/048 ,  G06F3/14 ,  G09G5/14 ,  G09G1/16 ,  G09G1/00

Abstract: The system comprises a pixel buffer in which the data to be displayed on the screen is stored and a mask buffer having a bit value corresp. to each pixel. The mask buffer is set in response to the demands of a particular application for screen display. A logic circuit uses data in the mask buffer to determine whether a pixel will be written during vector or character drawing. The buffer has multiple display planes, each containing the same number of pixels as the screen can display. The operation of the mask and the selection of the display plane is under control of a microprocessor with its associated Random Access and Read Only memories. The logic circuit may be simulated in software if hardware operation is not possible.

公开(公告)号：CA1229439A

公开(公告)日：1987-11-17

申请号：CA469784

申请日：1984-12-11

Applicant: IBM

Inventor： IMPEY ALAN A ,  POWELL COLIN V ,  SIMMONS JOHN ,  EASTON COLIN J

IPC: G09G5/377 ,  G06F3/048 ,  G06F3/14 ,  G09G5/14 ,  G09G3/00

Abstract: A display system which is used as the input-output terminal of a data processing system which may be used for concurrent processing of application. Each application may have a viewport on the display screen and viewports may overlap. In order to write to low priority viewports without disturbing data displayed in those of a higher priority a mask buffer is used to prevent overwriting of high priority viewports. More particularly, this application describes a multi-viewport system in which the writing of application data into overlapping viewports is controlled by a screen manager. The screen manager maintains a series of priority flags for each pixel (bit in the screen buffer) relating to the layers of the viewports, and a viewport order list. Only the current, or higher priority viewport is written into by an application. There is no provision for having more than one application writing into a lower priority viewport overlapped by the current viewport other than serially, i.e. writing to one viewport is completed before processing the next one. The main advantage of the present invention is that lower priority viewports may be written into requiring only a single pass over the data held in a data buffer, and it is able to handle the most complex of overlaid viewports.