DATA TRANSFER CONTROL METHOD BETWEEN CENTRAL PROCESSING UNIT AND INPUT/OUTPUT DEVICE, INFORMATION PROCESSOR AND INFORMATION PROCESSING SYSTEM

摘要

PURPOSE: To suppress the deterioration of processing capacity in a central processing unit by setting a data transfer mode most suitably at the time of transferring data between the central processing unit and an input/output device. ;CONSTITUTION: An I/O controller 2 corresponding to the I/O device 3 is designated under the control of the central processing unit 1 at the time of transferring data between the central processing unit 1 and the input/output (I/O) device 3, and data is transferred between the central processing unit 1 and the I/O device 3 in accordance with one data transfer mode between a program transfer mode and a DMA transfer mode. When processing speed in the I/O device 3 is slow or when transfer data are many, the DMA mode is selected. Thus, the central processing unit 1 issues a command to the I/O controller 2 and it is released from I/O control while a status is returned so as to execute the other processing during that time.;COPYRIGHT: (C)1993,JPO&Japio