DMA TRANSFER DEVICE

PROBLEM TO BE SOLVED: To eliminate useless time and to speedily transfer the data to an external bus by discontinuing the transfer of data to the external bus when the address of the data to be transferred to the external bus exceeds the address of the transfer data which are stored in a transfer data storing buffer. SOLUTION: A DMA control circuit 15 reads the transfer data out of a memory 13 which is connected to a system bus 11 of a CPU 12 and stores the data in a transfer data storing buffer 17. An LSI 18 transfers the data stored in the buffer 17 to an external bus 20. An address comparator 16 judges whether the address of the data to be transferred to the bus 20 from the LSI 18 exceeds the address of the transfer data stored in the buffer 17. If the former address exceeds the latter one, the circuit 15 discontinues the transfer of data to the bus 20.