EP0019045A2
Expired / Lapsed
EP
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Graphics display apparatus
Assignee: International Business Machines Corp
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Filing: 1980-03-11
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Granted: —
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Expires: 2000-03-11
Abstract
Abstract A cell-organized graphic display apparatus is described in ' which a set of canonical or standard cells is stored in a character generator (17). A data processor (not shown) loads character codes into a character buffer (14) and attribute bits into an attribute buffer (16). Lines to be displayed are computed on a cell-by-cell basis by the processor using two canonical cells and the computed character codes are stored in the character buffer (14): attribute bits representing displacements of the required canonical cells are loaded into the attribute buffer (16). During accessing of the character generator (17), an adder (20) shifts the bit patterns in accordance with the attribute bits. Optionally a second character buffer (40), a second character generator (39) and a logic mixer (37) are used to allow logical combining of cell images in accordance with attribute bits.
Inventors
- 👤 Alan Stanley Murphy
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-10-28 22:03
CPC Classifications
G; G09; G09G; G09G5/00; G09G5/22; G09G5/30
Claims Analysis
Total Claims: 11
Claim 1
Independent Claim
221 words
A cell-organized graphic display apparatus comprising a point-addressable display device, a character buffer adapted to contain character codes of image cells to be displayed, a character generator adapted to contain bit patterns representing image cells including a set of canonical cells, means for reading character codes from said character buffer to access related bit patterns within said character generator, means for applying said accessed bit patterns to said display device, and a data processor adapted to load said character buffer with character codes representing image cells required to be displayed on said display device, characterized in that said apparatus further includes an attribute buffer adapted to contain attribute bits associated with the character codes stored in said character buffer and means adapted to shift the bit patterns obtained from said character generator in accordance with associated attribute bits contained in said attribute buffer, and characterized in that said data processor is operable when a line is required to be displayed on said display device to select a pair of canonical cells whose slopes span the slope of the required line, to compute the displacements of the chosen canonical cells required to display said required line, and to store character codes representing said required canonical cells in said character buffer and attribute bits indicative of their required displacements in said attribute buffer.
Claim 2
Dependent Claim
221 words
A cell-organized graphic display apparatus comprising a point-addressable display device, a character buffer adapted to contain character codes of image cells to be displayed, a character generator adapted to contain bit patterns representing image cells including a set of canonical cells, means for reading character codes from said character buffer to access related bit patterns within said character generator, means for applying said accessed bit patterns to said display device, and a data processor adapted to load said character buffer with character codes representing image cells required to be displayed on said display device, characterized in that said apparatus further includes an attribute buffer adapted to contain attribute bits associated with the character codes stored in said character buffer and means adapted to shift the bit patterns obtained from said character generator in accordance with associated attribute bits contained in said attribute buffer, and characterized in that said data processor is operable when a line is required to be displayed on said display device to select a pair of canonical cells whose slopes span the slope of the required line, to compute the displacements of the chosen canonical cells required to display said required line, and to store character codes representing said required canonical cells in said character buffer and attribute bits indicative of their required displacements in said attribute buffer.
Claim 3
Dependent Claim
38 words
Apparatus as claimed in claim 1, characterized in that said shifting means includes an adder connected to receive attribute bits from said attribute buffer and to modify addressing of said character generator in accordance with the attribute bits.
Claim 4
Dependent Claim
28 words
Apparatus as claimed in claim 2, characterized in that said adder has an overflow/underflow output arranged to control the gating of said accessed bit patterns through a gate.
Claim 5
Dependent Claim
41 words
Apparatus as claimed in either of claims 2 and 3, characterized in that means adapted to select the true or inverted output of said adder is provided to allow selective rotation of the bit pattern associated with a selected image cell.
Claim 6
Dependent Claim
26 words
Apparatus as claimed in any preceding claim, characterized in that said shifting means includes horizontal shift logic connected to receive the output of said character generator.
Claim 7
Dependent Claim
58 words
Apparatus as claimed in any preceding claim, characterized in a mask store adapted to store bit patterns indicative of masks, and logic mixing means adapted to logically combine a bit pattern representing a selected mask with an associated bit pattern representing an image cell from said character generator in accordance with attribute bits stored in said attribute buffer.
Claim 8
Dependent Claim
43 words
Apparatus as claimed in any of claims 1 to 5, characterized in a second character buffer loadable with character codes from said data processor, a second character buffer, and mixing means for logically combining bit patterns from said first and second character generator.
Claim 9
Dependent Claim
23 words
Apparatus as claimed in claim 7, characterized in that said mixing means is operable under control of attribute bits from said attribute buffer.
Claim 10
Dependent Claim
36 words
Apparatus as claimed in either claim 7 or claim 8, characterized in that said mixing means is a summing amplifier arranged to give different intensity values to image cells to be displayed on said display device.
Claim 11
Dependent Claim
21 words
Apparatus as claimed in any preceding claim, characterized in that the or each character generator is writable from said data processor.
References Cited (Backward Citations)
No citation records indexed.
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