Apparatus for controlling data transfer between storages

Claim 1

An apparatus for controlling a data transfer between storages having a main storage, an extended storage, a transmission path between said main storage and said extended storage for transmitting data therebetween, a data buffer provided on said transmission path, and a processor in which the data is transferred between the main storage and the extended storage by use of a synchronous instruction and an asynchronous instruction comprising: means for holding data transfer control information supplied from the processor in response to the synchronous instruction; means for holding data transfer control information supplied from the processor in response to the asynchronous instruction; select means for selecting data transfer information held in a one of said hold means; and control means for selecting, by means of said select means, the hold means associated with an instruction depending on whether the instruction is a synchronous instruction or an asynchronous instruction, for controlling the data transfer between said main storage and said extended storage based on a content of said selected hold means, and for updating the content of said selected hold means according to an amount of data to be transferred, wherein said control means, when a request of a data transfer is issued by a synchronous instruction while a data transfer caused by an asynchronous instruction is being executed, controls to interrupt the data transfer of the asynchronous instruction and to select by use of said select means the information in said hold means holding data transfer control information of the synchronous instruction; and in response to a completion of the data transfer, said control means controls said select means to select the information in said hold means holding data transfer control information of the asynchronous instruction by means of said select means and to resume the data transfer of the asynchronous instruction interrupted, wherein the data transfer between said main storage and said extended storage is effected in a unit of a block of data, the data transfer by the asynchronous instruction comprising transfer of a plurality of blocks, and when a data transfer is requested by a synchronous instruction during a data transfer caused by an asynchronous instruction, said select means are caused, in response to a completion of a transfer of a block of the data, to select the content of said hold means holding data transfer control information of the synchronous instruction, thereby achieving a data transfer of the synchronous instruction.

Claim 2

An apparatus for controlling a data transfer between storages having a main storage, an extended storage, a transmission path between said main storage and said extended storage for transmitting data therebetween, a data buffer provided on said transmission path, and a processor in which the data is transferred between the main storage and the extended storage by use of a synchronous instruction and an asynchronous instruction comprising: means for holding data transfer control information supplied from the processor in response to the synchronous instruction; means for holding data transfer control information supplied from the processor in response to the asynchronous instruction; select means for selecting data transfer information held in a one of said hold means; and control means for selecting, by means of said select means, the hold means associated with an instruction depending on whether the instruction is a synchronous instruction or an asynchronous instruction, for controlling the data transfer between said main storage and said extended storage based on a content of said selected hold means, and for updating the content of said selected hold means according to an amount of data to be transferred, wherein said control means, when a request of a data transfer is issued by a synchronous instruction while a data transfer caused by an asynchronous instruction is being executed, controls to interrupt the data transfer of the asynchronous instruction and to select by use of said select means the information in said hold means holding data transfer control information of the synchronous instruction; and in response to a completion of the data transfer, said control means controls said select means to select the information in said hold means holding data transfer control information of the asynchronous instruction by means of said select means and to resume the data transfer of the asynchronous instruction interrupted, wherein the data transfer between said main storage and said extended storage is effected in a unit of a block of data, the data transfer by the asynchronous instruction comprising transfer of a plurality of blocks, and when a data transfer is requested by a synchronous instruction during a data transfer caused by an asynchronous instruction, said select means are caused, in response to a completion of a transfer of a block of the data, to select the content of said hold means holding data transfer control information of the synchronous instruction, thereby achieving a data transfer of the synchronous instruction.