PURPOSE: To use effectively a single bus and shorten the processing time for the conversion and the transfer of the data by carrying out the conversion and the transfer by the use of the conversion table or the descriptor.

CONSTITUTION: When the data stored in the data area 301 of the peripheral device 5 is converted based on the conversion table 204 in the memory device 2, and is stored into the data area 401 of the peripheral device 6, the descriptor 202 for the transmission side processing device which is set to the control register 32 in the data processing device 1 is analyzed by the conversion control circuit 33 in the device 1, which processing device is the trnasmission side processing device is decoded, under the control of the microinstruction stored in the microinstruction memory device 31, the command is transmitted from the data processing device 1 through a single bus 101 to the peripheral control device 3 of the transmission processing device and by this command, the peripheral control circuit 13 is initiated and the data from the area 301 is loaded to the buffer register 34 in the device 1 through the single bus.