Direct Memory Access

To be more specific-

Direct Memory Access (DMA) is a capability provided by some computer bus architectures that allows data to be sent directly from an attached device (such as a disk drive) to the memory on the computer's motherboard. The microprocessor is freed from involvement with the data transfer, thus speeding up overall computer operation.
Usually a specified portion of memory is designated as an area to be used for direct memory access. In the ISA bus standard, up to 16 megabytes of memory can be addressed for DMA. The EISA and Micro Channel Architecture standards allow access to the full range of memory addresses (assuming they're addressable with 32 bits). Peripheral Component Interconnect accomplishes DMA by using a bus master (with the microprocessor "delegating" I/O control to the PCI controller).


Edited by Chao (14/01/2002 21:07)