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公开(公告)号：CA2021831A1
公开(公告)日：1991-04-13
申请号：CA2021831
申请日：1990-07-24
Applicant: IBM
Inventor： HARRISON ROY B , WOOD ROGER T , HAIGH DAVID C
Abstract: A display system has, in addition to a display memory for the main storage of display information for a character mode, a separate cache for the temporary storage of the definitions of one or more fonts currently required for display and control logic for updating the font cache from the display memory. This enables the efficient support of a character mode on a display system, particularly where the display memory of that system is implemented with dual-ported memory technology. Compatibility with existing display standards is achieved.
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公开(公告)号：CA2021829A1
公开(公告)日：1991-04-13
申请号：CA2021829
申请日：1990-07-24
Applicant: IBM
Inventor： WOOD ROGER T , HARRISON ROY B
Abstract: DISPLAY SYSTEM A display system is presented, comprising an all points addressable display buffer, in which a pixel is represented by an n bit pixel word; and in which a display character is represented by a pixel matrix comprising a plurality of pixels arranged in a plurality of pixel rows, a character font table for storing a plurality of such character pixel matrices representative of display characters of a font, and control logic responsive to a character code word for selecting a desired pixel matrix from the character font table, wherein each pixel matrix is stored in the character font table in an m bit (m
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公开(公告)号：CA2021827C
公开(公告)日：1995-05-23
申请号：CA2021827
申请日：1990-07-24
Applicant: IBM
Inventor： HARRISON ROY B , WOOD ROGER T
Abstract: Display data is stored in a display memory in densely packed format in all display modes thanks to memory controller logic which modifies original addresses for mapping display data into the display memory such that a stream of data for driving a display device can be generated from sequential memory locations. This enables the display memory to take advantage of the benefits of dual-ported memory technology whilst maintaining compatibility with VGA display modes. In order to provide complete VGA compatibility, even in unusual applications, a duplicate auxiliary display memory for the storage of the display data in accordance with the original addresses can be provided. This auxiliary display memory is not used for updating the display, but solely for the retrieval of the display data.
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公开(公告)号：CA1328513C
公开(公告)日：1994-04-12
申请号：CA588444
申请日：1989-01-17
Applicant: IBM
Inventor： WOOD ROGER T
Abstract: DISPLAY SYSTEM COMPRISING A WINDOWING MECHANISM In a display system having a palette 38 for chrominance and/or luminance information, a display buffer 36 for information defining the pixels of a display field, including index values for indexing the palette to select the chrominance and/or luminance of the pixels, a windowing mechanism is provided for associating a different range of index values with each of a plurality of windows and for responding to index values stored at individual pixel positions in the display buffer to determine the visible extent of a given window within the display field. This allows a plurality of windows to be displayed with a minimum of extra logic and without unduly constraining the choice of colours available within those windows. In the described embodiment, windows are defined in a first phase by storing index values from the range of values associated with that window at all pixel positions for that window. Then, in a second phase, the output of a range comparator 46 for comparing index values stored in the display buffer to the range of values associated with a given window is used to control multiplexer means 60 to cause an item of update information destined for a particular pixel position to be stored at that pixel position in the display buffer only if the comparison is positive.
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