Each method and means for simulating direct memory access and its functionality, a computer program for simulating a direct memory accessor, a computer system and a subsystem

摘要

A DMA controller (DMA controller) is used to enable data transfer between a host memory and a computer accessory data handling device that may be operatively connected to the host but is not capable of DMA operation. There is provided a method and means for simulating direct memory access to access memory in a host computer having a DMA controller that reads the memory address access of the DMA controller , Determining the location in the host memory for data to be transferred from host memory to the accessory data processing unit or from the accessory data processing unit to the host memory. The data is read from the host memory at the address specified in the DNA controller, written to the accessory data processing device or read from the accessory data processing device and written to the host memory at the address specified in the DNA controller. The host computer is notified that the DMA operation corresponding to this data transfer is completed when the requested data transfer is completed.