DMA (Direct Memory Access) is a fast way of transferring data within (and sometimes between) computers. For example, DMA is often used to read data from a LAN adapter board or a Hard Disk Drive and write it directly into a PC's memory without having to interrupt the CPU's duty cycles. This makes the CPU more available to perform other tasks.PCI (Peripheral Component Interconnect) accomplishes DMA by using a bus master (with the microprocessor "delegating" I/O control to the PCI controller). Ultra DMA (used by all new IDE HDD's) allows burst data transfer rates of up to 100MB/sec, but as only 2 devices may coexist on each IDE channel, it is not likely that this bandwidth is ever used in a conventional setup.