Patent US5030946A successfully refreshed from Google Patents.
US5030946A
Expired / Lapsed
US
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Apparatus for the control of an access to a video memory
Assignee: Hudson Soft Co Ltd
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Filing: 1988-03-29
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Granted: 1991-07-09
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Expires: 2008-03-29
Abstract
Abstract An apparatus for the control of an access to a video memory comprises a memory width register having a content of a number of dot periods by which an access timing is determined to address a video memory. Therefore, an access timing is easily controlled dependent on a memory speed of the video memory only by changing the content of the memory width register. When the video memory is accessed during a display cycle of the video memory, video data may be stored in a buffer memory, and transferred from the buffer memory after the display cycle is finished.
Inventors
- 👤 Kimio Yamamura
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-02 16:39
CPC Classifications
G; G09; G09G; G09G5/00; G09G5/42; G09G5/22; G09G5/222; G09G5/227
Claims Analysis
Total Claims: 17
Claim 1
Independent Claim
93 words
An apparatus for the control of an access to a video memory comprising: register means for storing a number of dot periods within a character cycle for processing the video memory; means for deciding said number of dot periods in accordance with said content of said register means; means for addressing said video memory at timings determined in accordance with said number of dot periods; and means for latching video data read from said video memory at said timings, wherein a pattern defined by said video data is displayed on a display screen.
Claim 2
Independent Claim
93 words
An apparatus for the control of an access to a video memory comprising: register means for storing a number of dot periods within a character cycle for processing the video memory; means for deciding said number of dot periods in accordance with said content of said register means; means for addressing said video memory at timings determined in accordance with said number of dot periods; and means for latching video data read from said video memory at said timings, wherein a pattern defined by said video data is displayed on a display screen.
Claim 3
Dependent Claim
53 words
An apparatus for the control of an access to a video memory according to claim 1, wherein said video data are read from a character generator in said video memory, and said character generator is addressed in accordance with a character code stored in a background attribute table included in said video memory.
Claim 4
Dependent Claim
30 words
An apparatus for the control of an access to a video memory according to claim 2, wherein said character generator includes four facts which are combined to define said pattern.
Claim 5
Dependent Claim
55 words
An apparatus for the control of an access to a video memory according to claim 2. further comprising buffer means for storing said video data which are read from said video memory during a display cycle of said video memory, said video data being stored until said display cycle of said video memory is finished.
Claim 6
Dependent Claim
40 words
An apparatus for the control of an access to a video memory according to claim 1, wherein said means for deciding said number of dot periods includes means for generating a frequency having a period equal to said dot period.
Claim 7
Dependent Claim
39 words
An apparatus for the control of an access to a video memory according to claim 5 wherein said means for generating a frequency having a period equal to said dot period includes an oscillator circuit and a frequency divider.
Claim 8
Dependent Claim
73 words
An apparatus for the control of an access to a video memory according to claim 1, wherein said means for addressing said video memory includes: a plurality of address registers; and address selector means responsive to said means for deciding said number of dot periods for selecting one of said address registers to be a selected address register and addressing said video memory in response to a content of said selected address register.
Claim 9
Dependent Claim
40 words
An apparatus for the control of an access to a video memory according to claim 7, wherein said means for deciding said number of dot periods includes means for generating a frequency having a period equal to said dot period.
Claim 10
Dependent Claim
39 words
An apparatus for the control of an access to a video memory according to claim 8, wherein said means for generating a frequency having a period equal to said dot period includes an oscillator circuit and a frequency divider.
Claim 11
Independent Claim
170 words
An apparatus for the control of an access to a video memory comprising; a video memory for storing video data; means for addressing said video memory; buffer means for storing video data to be written into said video memory and to be read out from said video memory; and means for controlling said buffer means to store said video data, and producing a wait signal to suspend an accessing of said addressing means to said video memory, wherein said controlling means controls said buffer means to store said video data without producing said wait signal, when said video memory is addressed for a display cycle of said video memory, said controlling means controls said addressing means to access said video memory to transfer said video data stored in said buffer means when said display cycle is finished, and said controlling means generates said wait signal when said video memory is to be accessed by said addressing means during a period when said video data is stored in said buffer means.
Claim 12
Independent Claim
170 words
An apparatus for the control of an access to a video memory comprising; a video memory for storing video data; means for addressing said video memory; buffer means for storing video data to be written into said video memory and to be read out from said video memory; and means for controlling said buffer means to store said video data, and producing a wait signal to suspend an accessing of said addressing means to said video memory, wherein said controlling means controls said buffer means to store said video data without producing said wait signal, when said video memory is addressed for a display cycle of said video memory, said controlling means controls said addressing means to access said video memory to transfer said video data stored in said buffer means when said display cycle is finished, and said controlling means generates said wait signal when said video memory is to be accessed by said addressing means during a period when said video data is stored in said buffer means.
Claim 13
Dependent Claim
35 words
An apparatus for the control of an access to a video memory according to claim 10, wherein said video memory includes timing means for generating a frequency having a period equal to said dot period.
Claim 14
Dependent Claim
28 words
An apparatus for the control of an access to a video memory according to claim 11, wherein said timing means includes an oscillator circuit and a frequency divider.
Claim 15
Dependent Claim
78 words
An apparatus for the control of an access to a video memory according to claim 10, wherein said means for addressing said video memory includes: a plurality of address registers; and address selector means responsive to a timing signal having a frequency with a period equal to a dot period for selecting one of said address registers to be a selected address register and addressing said video memory in response to a content of said selected address register.
Claim 16
Dependent Claim
28 words
An apparatus for the control of an access to a video memory according to claim 13, wherein said video memory includes timing means for generating said timing signal.
Claim 17
Dependent Claim
28 words
An apparatus for the control of an access to a video memory according to claim 14, wherein said timing means includes an oscillator circuit and a frequency divider.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1994-07-08 | 1995-01-07 | 1995-07-09 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1998-07-08 | 1999-01-07 | 1999-07-09 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2002-07-08 | 2003-01-07 | 2003-07-09 | $7700.00 | Window Closed / Lapsed |