US5016160A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Computer system having efficient data transfer operations
Assignee: International Business Machines Corp
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Filing: 1988-12-15
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Granted: 1991-05-14
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Expires: 2008-12-15
Abstract
Abstract A computer system has a system memory, a central processing unit, an input/output controller, and at least one device. When the central processing unit wants data transferred to/from system memory from/to the device, it sends Indirect DAta Address Word (IDAW) commands to the I/O controller. Instead of performing a direct memory access (DMA) operation for each IDAW command, the I/O controller starts an IDAW look ahead procedure. In this procedure, the I/O controller checks to see if the system addresses of the system memory specified in the IDAW commands are contiguous. If so, the procedure combines IDAWs that specify contiguous system addresses up to the maximum DMA transfer length. Using this procedure, the number of DMA operations sent to the system memory is minimized, and the computer system has more efficient data transfer operations.
Inventors
- 👤 Shawn M. Lambeth
- 👤 Lee P. Prissel
- 👤 William D. Tarara
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-02 12:29
CPC Classifications
G; G06; G06F; G06F13/00; G06F13/14; G06F13/20; G06F13/28
Claims Analysis
Total Claims: 13
Claim 1
Independent Claim
101 words
A computer system having efficient data transfer operations, comprising: a system memory having system addresses; a central processing unit connected to said system memory; means for receiving a plurality of indirect data address word commands from said central processing unit; means for combining said plurality of indirect data address word commands to form a lesser number of combined indirect data address word commands if the system addresses specified in said indirect data address word commands are contiguous; and means for transmitting data between said system memory specified by said combined indirect address word commands and another component of said computer system.
Claim 2
Dependent Claim
101 words
A computer system having efficient data transfer operations, comprising: a system memory having system addresses; a central processing unit connected to said system memory; means for receiving a plurality of indirect data address word commands from said central processing unit; means for combining said plurality of indirect data address word commands to form a lesser number of combined indirect data address word commands if the system addresses specified in said indirect data address word commands are contiguous; and means for transmitting data between said system memory specified by said combined indirect address word commands and another component of said computer system.
Claim 3
Dependent Claim
33 words
The computer system of claim 1, further comprising: means for stopping said combining means when the length of said combined indirect data address word commands exceeds a predetermined direct memory address transfer length.
Claim 4
Dependent Claim
26 words
The computer system of claim 1, further comprising means for stopping said combining means when there are no more indirect data address word commands to process.
Claim 5
Dependent Claim
30 words
The computer system of claim 1, wherein said means for transmitting data transmits data between said system memory specified by said combined indirect address word commands and an input/output controller.
Claim 6
Dependent Claim
19 words
The computer system of claim 4, wherein said input/output controller controls one or more direct access storage device units.
Claim 7
Dependent Claim
17 words
The computer system of claim 4, wherein said input/output controllers controls one or more tape unit devices.
Claim 8
Dependent Claim
96 words
An input/output controller, for connecting to a system memory having system addresses and to a central processing unit, said input/output controller comprising: means for receiving a plurality of indirect data address word commands from said central processing unit; means for combining said plurality of indirect data address word commands to form a lesser number of combined indirect data address word commands if the system addresses specified in said indirect data address word commands are contiguous; and means for transmitting data between said input/output controller and said system memory specified by said combined indirect address word commands.
Claim 9
Dependent Claim
96 words
An input/output controller, for connecting to a system memory having system addresses and to a central processing unit, said input/output controller comprising: means for receiving a plurality of indirect data address word commands from said central processing unit; means for combining said plurality of indirect data address word commands to form a lesser number of combined indirect data address word commands if the system addresses specified in said indirect data address word commands are contiguous; and means for transmitting data between said input/output controller and said system memory specified by said combined indirect address word commands.
Claim 10
Independent Claim
119 words
A method of data transfer in a computer system having a system memory, a central processing unit connected to said system memory, an input/output controller connected to said system memory, said system memory having system addresses, said method comprising the steps of: said input/output controller receiving a plurality of indirect data address word commands from said central processing unit; said input/output controller combining said plurality of indirect data address word commands to form a lesser number of combined indirect data address word commands if the system addresses specified in said indirect data address word commands are contiguous; and said input/output controller transmitting data between said input/output controller and said system memory specified by said combined indirect address word commands.
Claim 11
Independent Claim
119 words
A method of data transfer in a computer system having a system memory, a central processing unit connected to said system memory, an input/output controller connected to said system memory, said system memory having system addresses, said method comprising the steps of: said input/output controller receiving a plurality of indirect data address word commands from said central processing unit; said input/output controller combining said plurality of indirect data address word commands to form a lesser number of combined indirect data address word commands if the system addresses specified in said indirect data address word commands are contiguous; and said input/output controller transmitting data between said input/output controller and said system memory specified by said combined indirect address word commands.
Claim 12
Dependent Claim
33 words
The method of claim 8, further comprising the step of: stopping said combining step when the length of said combined indirect data address word commands exceeds a predetermined direct memory address transfer length.
Claim 13
Dependent Claim
27 words
The method of claim 8, further comprising the step of: stopping said combining step of when there are no more indirect data address word commands to process.
References Cited (Backward Citations)
US4075688A
Cited
US3967104A
Cited
US4056843A
Cited
US4354231A
Cited
US4272815A
Cited
US4346439A
Cited
US4368513A
Cited
US4651274A
Cited
US4901232A
Cited
US4564903A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1994-05-13 | 1994-11-12 | 1995-05-14 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1998-05-13 | 1998-11-12 | 1999-05-14 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2002-05-13 | 2002-11-12 | 2003-05-14 | $7700.00 | Window Closed / Lapsed |