US 5,848,253 A · 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

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.

Claims10

Dependent claims

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.

5 more elements

Dependencies are inferred from the claim text.

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

Life of this patent

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

Life of this patent

Abstract

Claims10