Patent ID: 7249237

Claim:
A control method for controlling data transfer by a control unit for controlling the operation of an upper-level host itself so that said control unit reads data of predetermined capacity from a device into a buffer memory of a host controller equipped in said upper-level host, and accepts an interruption issued from said device after said device transfers the data of predetermined capacity to said host controller, said control method comprising: a data reading restricted step of said host controller reading the data from said device into said buffer memory for a unit amount with a part of the data of predetermined capacity left in said device; a data transfer step of said control unit reading the data of said unit amount temporarily held in said buffer memory; a buffer memory capacity detecting step of said host controller detecting whether or not said buffer memory is empty in parallel with said data transfer step; and a residual data reading step of said host controller reading the data corresponding to the part of data of said predetermined capacity from said device into said buffer memory when said buffer memory is empty at said buffer memory capacity detecting step.