Patent US5848253A successfully refreshed from Google Patents.
US5848253A
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Computer system and an electronic circuit utilizing a single DMA controller and additional communication circuit to manage DMA transfers between memory and I/O devices
Assignee: Texas Instruments Inc
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Filing: 1997-01-22
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Granted: 1998-12-08
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Expires: 2017-01-22
Abstract
Abstract A computer system (6,7) includes first and second I/O circuits (932, 934), first and second buses (904, 83) respectively coupled to the first and second I/O circuits (932, 934), a memory (106), a third bus (104) coupled to the memory (106), and first and second bus interface circuits (902, 6920) connected between the third bus (104) and the first and second buses (904, 83) respectively. A direct memory access (DMA) controller (910) is coupled to the first bus (904) and to the first bus interface circuit (906), and a serial communications circuit (7010, 6910, 7020) is connected between the DMA controller (910) and the second bus interface circuit (6920). As an example, in the present invention a single DMA controller may be used to provide DMA capability to both a notebook computer and a docking station, using an interface between the notebook computer and the docking station to transfer DMA station. Other devices, systems and methods are also disclosed.
Inventors
- 👤 James J. Walsh
- 👤 Joseph Joe
- 👤 Robert W. Milhaupt
- 👤 James Bridgwater
- 👤 Kazumi Haijima
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-07 09:34
CPC Classifications
G; G06; G06F; G06F13/00; G06F13/14; G06F13/20; G06F13/28; Y; Y02; Y02D; Y02D10/00
Claims Analysis
Total Claims: 11
Claim 1
Independent Claim
136 words
A computer system, comprising: first and second I/O circuits; first and second buses respectively coupled to said first and second I/O circuits; a memory; a third bus coupled to said memory; first and second bus interface circuits coupled between said third bus and said first and second buses respectively; a direct memory access (DMA) controller coupled to said first bus and to said first bus interface circuit; and a communications circuit coupled between said DMA controller and said second bus interface circuit for facilitating DMA transfers via either said third bus and said first bus interface and second bus interface circuits or via said communications circuit and said second bus interface circuit, in dependence upon whether a memory cycle is granted by a device other than said second I/O circuit or by said second I/O circuit.
Claim 2
Dependent Claim
136 words
A computer system, comprising: first and second I/O circuits; first and second buses respectively coupled to said first and second I/O circuits; a memory; a third bus coupled to said memory; first and second bus interface circuits coupled between said third bus and said first and second buses respectively; a direct memory access (DMA) controller coupled to said first bus and to said first bus interface circuit; and a communications circuit coupled between said DMA controller and said second bus interface circuit for facilitating DMA transfers via either said third bus and said first bus interface and second bus interface circuits or via said communications circuit and said second bus interface circuit, in dependence upon whether a memory cycle is granted by a device other than said second I/O circuit or by said second I/O circuit.
Claim 3
Dependent Claim
23 words
The computer system claimed in claim 1 further comprising an interrupt controller coupled to said first bus, and coupled to said communications circuit.
Claim 4
Dependent Claim
26 words
The computer system claimed in claim 1 wherein said first and second buses each comprise an ISA bus, and said third bus comprises a PCI bus.
Claim 5
Dependent Claim
39 words
The computer system claimed in claim 1 further comprising a first circuit board, wherein said first bus, said first bus interface circuit, said first I/O circuit, said DMA controller and said memory are located on said first circuit board.
Claim 6
Dependent Claim
34 words
The computer system claimed in claim 4 further comprising a second circuit board, wherein said second bus, said second bus interface circuit, and said second I/O circuit are located on said second circuit board.
Claim 7
Dependent Claim
20 words
The computer system claimed in claim 5 wherein said third bus couples between said first and second printed circuit boards.
Claim 8
Dependent Claim
42 words
The computer system claimed in claim 1 further comprising first and second circuit boards wherein said third bus couples between said first and second circuit boards and said communications circuit comprises a serial line coupling between said first and second circuit boards.
Claim 9
Dependent Claim
39 words
The computer system claimed in claim 1 wherein said communications circuit is coupled to transfer DMA requests from said second bus to said DMA controller and further to transfer DMA acknowledges from said DMA controller to said second bus.
Claim 10
Dependent Claim
26 words
The computer system claimed in claim 1 wherein said communications circuit is coupled to transfer a master request from said second bus to said DMA controller.
Claim 11
Dependent Claim
28 words
The computer system claimed in claim 1 wherein said communications circuit is coupled to transfer a current address from said DMA controller to said second bus interface circuit.
References Cited (Backward Citations)
US4235496A
Cited
US5134580A
Cited
US5377357A
Cited
US5301343A
Cited
US5359715A
Cited
US5467295A
Cited
US5313596A
Cited
US5463742A
Cited
US5450551A
Cited
US5517671A
Cited
US5475854A
Cited
US5488572A
Cited
US5619728A
Cited
US5542053A
Cited
US5621902A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 2001-12-07 | 2002-06-08 | 2002-12-08 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2005-12-07 | 2006-06-08 | 2006-12-08 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2009-12-07 | 2010-06-08 | 2010-12-08 | $7700.00 | Window Closed / Lapsed |