US3789200A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Circle or arc generator for graphic display
Assignee: International Business Machines Corp
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Filing: 1972-06-30
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Granted: 1974-01-29
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Expires: 1992-06-30
Abstract
Abstract The operations in a data processing system for drawing circles or other geometric figures on a display which are conventionally defined by a series of instructions prepared by a problem programmer are included in a standardized form in a small memory that is made part of the display unit. The problem programmer has only to specify either the starting point of an arc of the center point of a circle, the radius of the arc or circle, and other optional characteristics such as whether the circle or arc is to be drawn clockwise or counter clockwise, whether the beam of the display is blanked or unblanked, and whether additional instructions for drawing additional arc segments are to be expected or requested by the display. Logic and timing means are provided for accessing the memory in response to these values specified by the problem programmer and for generating a desired sequence of X and Y incremental signals for operating the display.
Inventors
- 👤 L Childress
- 👤 R Gundrum
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-24 03:20
CPC Classifications
G; G09; G09G; G09G1/00; G09G1/06; G09G1/08; G09G1/10
Claims Analysis
Total Claims: 9
Claim 1
Independent Claim
214 words
A system for controlling a graphic device to produce one of a plurality of geometric figures composed at least in part of chords of a circle, comprising; means for storing a table of functions defining a succession of chords, means for decoding data bytes supplied by a problem program , including first means for decoding a byte defining an operating mode in which the system is to produce one of said figures, means operable when said system is in said mode for accessing said table storing means for a function defining a next chord, means connected to receive the accessed function for forming chord defining signals and means for transmitting said signals to said device, and means for identifying the position of an accessed chord in said succession of chords, said decoding means including second means responsive to a set of control bits supplied by a problem program defining an end chord, and means for comparing said position of an accessed chord and said signal defining said end chord for signalling the completion of the end chord to said means for accessing said table storing means, whereby a graphic device is controlled to form a selected figure in response to said bytes supplied by said problem program without further intervention by said problem program.
Claim 2
Independent Claim
214 words
A system for controlling a graphic device to produce one of a plurality of geometric figures composed at least in part of chords of a circle, comprising; means for storing a table of functions defining a succession of chords, means for decoding data bytes supplied by a problem program , including first means for decoding a byte defining an operating mode in which the system is to produce one of said figures, means operable when said system is in said mode for accessing said table storing means for a function defining a next chord, means connected to receive the accessed function for forming chord defining signals and means for transmitting said signals to said device, and means for identifying the position of an accessed chord in said succession of chords, said decoding means including second means responsive to a set of control bits supplied by a problem program defining an end chord, and means for comparing said position of an accessed chord and said signal defining said end chord for signalling the completion of the end chord to said means for accessing said table storing means, whereby a graphic device is controlled to form a selected figure in response to said bytes supplied by said problem program without further intervention by said problem program.
Claim 3
Dependent Claim
88 words
The system of claim 1 wherein said means for decoding data bytes comprises third means for storing a radius length word supplied by said problem program, and said means for forming chord defining signals includes a multiplier for multiplying the radius length by a function accessed in said table to produce said chord defining signals, whereby circles or related figures of preselected radius may be formed by said device in response to control bits supplied by said problem program defining said end, said radius, and said operating mode.
Claim 4
Dependent Claim
110 words
The system of claim 2 wherein said first means for decoding bytes produced by a problem program includes means to decode and store a first bit defining a circle mode or a second bit defining an arc mode operation called for by said problem program, and said means to form said chord defining signals includes means operable in said circle mode before forming said first chord to control said device to move its trace in a predetermined direction by said radius length, whereby the trace position defined by an operation immediately preceding said radius length storing operation defines the center of a circle or a partial circle to be formed.
Claim 5
Dependent Claim
62 words
The system of claim 3 wherein said decoding means includes means operable in arc mode for storing control bits defining a selected starting address in said table storing means, and said means for accessing said table storing means includes means to begin an accessing sequence at a predetermined position in said circle mode and at said selected starting address in arc mode.
Claim 6
Dependent Claim
61 words
The system of claim 2 wherein said means for decoding includes fourth means for controlling said device according to a control bit position in a byte supplied bY a problem program defining a blanked or unblanked condition for said device, whereby the trace may be moved to a position defined by a sequence of chords without visible representation in the device.
Claim 7
Dependent Claim
111 words
The system of claim 5 wherein said second means for decoding includes means operable in response to a first group of control bytes to store said end value and includes means differently responsive to a second group of control bytes to store first and second end values, and said means for signalling the completion of an end chord includes means repsonsive to the completion of a chord succession defined by a first end value to begin an operation defined by the second end value and responsive to the completion of said chord defined by said second end value to produce a request to the problem program source for a next message.
Claim 8
Dependent Claim
91 words
The system of claim 6 wherein said first means for decoding bytes produced by said problem program includes means responsive to predetermined bit positions in the message format for other device operations, and said decoding means is operable only when said system is in said mode, whereby the trace of said device moved to a starting position for drawing one of said figures in response to a message containing a mode defining bit and thereafter responds to a subsequent message containing bits defining said end chord, said radius, and other parameters.
Claim 9
Dependent Claim
68 words
The system of claim 7 wherein said decoding means includes fifth means responsive to a bit defining whether the operation is to continue with further such control bytes after an end chord forming operation, and said chord forming means includes means responsive to said continue bit to selectively reset or maintain the accessing position for said table storing means at the completion of an end chord forming operation.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1977-01-28 | 1977-07-30 | 1978-01-29 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1981-01-28 | 1981-07-30 | 1982-01-29 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1985-01-28 | 1985-07-30 | 1986-01-29 | $7700.00 | Window Closed / Lapsed |