EP0071744A2
Expired / Lapsed
EP
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Method for operating a computing system to write text characters onto a graphics display
Assignee: International Business Machines Corp
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Filing: 1982-06-29
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Granted: —
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Expires: 2002-06-29
Abstract
Abstract Method and system for writing text characters to a raster scan video display (50, 51) operated in an all-points- addressable, or graphics mode, and for reading characters thus written. A graphic video display buffer (34) directly refreshes the display (50) with graphics data received from a microprogrammed processor (20). The processor (20) writes a character to the display (50) by selecting and loading into the graphics video display buffer (34) a text character dot pattern retrieved from main storage (25, 27), and expanded to a selected pixel and color format, and reads a character previously written by comparing a dot pattern retrieved from the display buffer (34) with dot pattern retrieved from main storage (25, 27).
Inventors
- 👤 David John Bradley
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-08 09:27
CPC Classifications
G; G09; G09G; G09G1/00; G09G1/28; G09G5/00; G09G5/02; G09G5/36; G09G5/39; G09G5/393
Claims Analysis
Total Claims: 11
Claim 1
Independent Claim
110 words
A method for operating a computing system to write text characters onto a graphics display, including a processor, a storage, and a display refresh buffer; the method being characterized by the steps of: establishing addressability to the location in said display refresh buffer to receive a selected display text character; establishing addressability to the location in said 'storage containing a dot image of said selected display text character, fetching one portion of said dot image from said storage, storing said one portion in said display refresh buffer, and, repeating said fetching and storing steps for each portion of said dot image to write the text character onto said graphics display.
Claim 2
Independent Claim
110 words
A method for operating a computing system to write text characters onto a graphics display, including a processor, a storage, and a display refresh buffer; the method being characterized by the steps of: establishing addressability to the location in said display refresh buffer to receive a selected display text character; establishing addressability to the location in said 'storage containing a dot image of said selected display text character, fetching one portion of said dot image from said storage, storing said one portion in said display refresh buffer, and, repeating said fetching and storing steps for each portion of said dot image to write the text character onto said graphics display.
Claim 3
Dependent Claim
56 words
The method according to claim 1, further comprising the steps of expanding each portion of said dot image according to a selected pixel format; then modifying each expanded dot image portion to encode a desired color; and storing each resulting modified expanded dot image portion in said display refresh buffer as part of each storing step.
Claim 4
Dependent Claim
44 words
The method according to claim 2, in which said expanding step and said modifying step are for the purpose of writing a text character in color and said expanding step and modifying step are eliminated when writing the text character in black and white.
Claim 5
Dependent Claim
39 words
The method according to claim 2 or 3 in which said storing step is performed by exclusive 'ORing each dot image portion with a corresponding portion of said modified expanded dot image previously stored in said display refresh buffer.
Claim 6
Dependent Claim
53 words
'The method according to any one of claims 1 to 4, further comprising the steps of: refreshing said display with alternate raster scan lines refreshed from offset locations of said display refresh buffer; and storing alternating dot image portions in offset locations of said display refresh buffer as part of said storing step.
Claim 7
Independent Claim
120 words
A method for additionally operating said computing system to read a text character previously written onto said graphics display by to the method according to any one of the preceding claims, comprising the steps of: retrieving from said display refresh buffer the dot image of the character to be read; storing the dot image of the character to be read in a save area in said storage; sequentially obtaining from said storage respective dot images of possible display text characters, comparing each respective dot image with the dot image in said save area; and repeating the obtaining and comparing steps until a respective dot image matches the dot image in said save area, thereby concluding reading of the text character.
Claim 8
Dependent Claim
98 words
A raster scan video display control system of the type including a graphic video display refresh buffer operable in an all points addressable mode for refreshing said display with graphics data, a processor for writing graphic data into said display refresh buffer, and a 'character storage for storing the character dot patterns of a display character font, characterized by: means for selecting a character to be displayed; and programmable control means referenced by said processor for loading from said storage into said graphic video display refresh buffer a character dot pattern corresponding to the character to be displayed.
Claim 9
Dependent Claim
98 words
A raster scan video display control system of the type including a graphic video display refresh buffer operable in an all points addressable mode for refreshing said display with graphics data, a processor for writing graphic data into said display refresh buffer, and a 'character storage for storing the character dot patterns of a display character font, characterized by: means for selecting a character to be displayed; and programmable control means referenced by said processor for loading from said storage into said graphic video display refresh buffer a character dot pattern corresponding to the character to be displayed.
Claim 10
Dependent Claim
59 words
The system according to claim 7, in which said programmable control means is also referencable by said processor for expanding the selected character dot pattern into a predetermined pixel format and then color encoding the expanded dot pattern to establish a resultant expanded/encoded dot pattern; and loading said expanded/ encoded dot pattern into said graphic video display refresh buffer.
Claim 11
Dependent Claim
51 words
The system according to claim 7 or 8 in which said programmable control means is also referencable by said processor to read a previously displayed character by comparing a character dot pattern previously loaded into said graphic video display refresh buffer with successive character dot patterns selected from said character storage.
References Cited (Backward Citations)
No citation records indexed.
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