COPROCESSOR SUPPORTING STRUCTURE SUITED TO PROCESSOR NOT SUPPORTING COPROCESSING ORIGINALLY

摘要

PURPOSE: To provide a method operating a coprocessor related to a main processor which does not support coprocessing originally. ;CONSTITUTION: A direct memory access(DMA) processor 11 is used for preparing DMA transfer between a local memory and an EISA bus. An address decoder 21 decodes the address value of the address line of an address bus 13 and generates a control signal 29 a state machine 22 uses. The state machine 22 generate a control signal 26 from this signal 29. This signal 26 selects a register from a DMA register 23 and receives data from a data bus 12. Viewed-through data is from the unused field of data transferred from an instruction from the local memory to the processor. A value in the data bus 12 is loaded to the DMA register 23 in response to the specific combination of the control signal 26. After loading, a DMA controller 24 supervises DMA transfer between the memory and the bus.;COPYRIGHT: (C)1993,JPO