Bidirectional data buffer for a bus-to-bus interface unit in a computer system

Claim 1

A computer system, comprising: system memory; a memory controller for controlling access to system memory, said system memory and said memory controller connected by a memory bus; a central processing unit coupled to said memory controller through a local bus, said central processing unit being connected to read data from and write data to said system memory over said local bus and said memory bus by performing read and write operations; a bus interface unit connected with said memory controller by a system bus; at least one input/output (I/O) device connected to said bus interface unit by an I/O bus for reading data from and writing data to said system memory over said bus interface unit; said bus interface unit including a bidirectional data storage unit to provide temporary storage of data being transferred between said system bus and said I/O bus during read and write operations performed by said at least one I/O device, said bidirectional storage unit comprising (i) a first pair of buffers connected in series between said I/O bus and said system bus, and (ii) a second pair of buffers connected in series between said I/O bus and said system bus and in parallel with said first pair of buffers, each of said buffers in each of said pairs being used for bidirectional data transfer between said system bus and said I/O bus wherein first and second sets of data originating on either one of said system bus or said I/O bus and destined for transfer in one direction to the other one of said system bus or said I/O bus are transferred to the bidirectional storage unit so that (a) said first set of data is stored in one buffer of one of the pairs of series-connected buffers, and (b) (1) said stored first set of data contained in said one buffer of one of the pairs of series-connected buffers is transferred to the other buffer in said one of the pairs while, simultaneously, (b) (2) said second set of data is transferred into one buffer of the other series-connected pair of buffers; wherein one of said first pair of buffers and one of said second pair of buffers is connected to said system bus, each of said system-bus connected buffers capable of simultaneously transferring data over said system bus.

Claim 7

A method of controlling data transfer between a system memory connected to a system bus and at least one input/output (I/O) device connected to an I/O bus in a computer system, wherein said system bus is coupled to said I/O bus by a bus interface unit comprising a first pair of buffers connected in series between said I/O bus and said system bus, and a second pair of buffers connected in series between said I/O bus and said system bus and in parallel with said first pair of buffers, the method comprising the steps of: transferring first and second sets of data originating on said I/O bus and destined for transfer in one direction to said system bus across said bus interface unit by: (a) temporarily storing said first set of data in one buffer of one of the pairs of series-connected buffers; simultaneously, (b) (1) transferring said stored first set of data contained in said one buffer of one of the pairs of series-connected buffers to the other buffer in said one of the pairs; and (b) (2) transferring said second set of data into one buffer of the other series-connected pair of buffers; (c) transferring said second set of data from said one buffer of said other series-connected pair of buffers to the other buffer of said other series-connected pair of buffers; and (d) (1) transferring said first set of data over said system bus from said other buffer in said one of the pairs of series-connected buffers while simultaneously (d) (2) transferring said second set of data over said system bus from said other buffer of said other series-connected pair of buffers.

Claim 8

A method of controlling data transfer between a system memory connected to a system bus and at least one input/output (I/O) device connected to an I/O bus in a computer system, wherein said system bus is coupled to said I/O bus by a bus interface unit comprising a first pair of buffers connected in series between said I/O bus and said system bus, and a second pair of buffers connected in series between said I/O bus and said system bus and in parallel with said first pair of buffers, the method comprising the steps of: transferring first and second sets of data originating on said I/O bus and destined for transfer in one direction to said system bus across said bus interface unit by: (a) temporarily storing said first set of data in one buffer of one of the pairs of series-connected buffers; simultaneously, (b) (1) transferring said stored first set of data contained in said one buffer of one of the pairs of series-connected buffers to the other buffer in said one of the pairs; and (b) (2) transferring said second set of data into one buffer of the other series-connected pair of buffers; (c) transferring said second set of data from said one buffer of said other series-connected pair of buffers to the other buffer of said other series-connected pair of buffers; and (d) (1) transferring said first set of data over said system bus from said other buffer in said one of the pairs of series-connected buffers while simultaneously (d) (2) transferring said second set of data over said system bus from said other buffer of said other series-connected pair of buffers.