DATA TRANSFER CONTROLLER

PROBLEM TO BE SOLVED: To recover a target device even when a fault occurs in the device while data transferring via a bus by giving a notification to a CPU if the number of times of data retransfering exceeds the maximum number of execution times stored in a storing means. SOLUTION: A transfer request control part 21 counts the retransfer times and outputs no transfer request to a master protocol control part 11 even when a transfer request is given from a master address/data control part 12 as long as the retransfer times counted at the part 21 exceeds the times stored in a retransfer limit register 22. In other words, a bus device 20 never requests the master right to a system bus 1 in times larger than those stored in the register 22. Meanwhile, an output is given to an interrupt control part 18 after detection of a fact that the retransfer times are equal to those stored in the register 22. Then the part 18 activates the interrupt signal of the sistem bus 1 to notify even a CPU of the discontinuation of transfer of data.