Search results
Results from the WOW.Com Content Network
It then instructs the DMA hardware to begin the transfer. When the transfer is complete, the device interrupts the CPU. Scatter-gather or vectored I/O DMA allows the transfer of data to and from multiple memory areas in a single DMA transaction. It is equivalent to the chaining together of multiple simple DMA requests.
This kind of transfer is implemented as "single mode transfer" in the Intel 8237 DMA controller. In multiword transfer mode, once a transfer has begun it will continue until all words are transferred or the drive negates the DMA request line. This mode is implemented as "demand mode transfer" in the Intel 8237 DMA controller.
RDMA supports zero-copy networking by enabling the network adapter to transfer data from the wire directly to application memory or from application memory directly to the wire, eliminating the need to copy data between application memory and the data buffers in the operating system.
In a burst transfer, the address for write or read transfer is just an incremental value of previous address. Hence in a 4-beat incremental burst transfer (write or read), if the starting address is 'A', then the consecutive addresses will be 'A+m', 'A+2*m', 'A+3*m'.
The first use of channel I/O was with the IBM 709 [2] vacuum tube mainframe in 1957, whose Model 766 Data Synchronizer was the first channel controller. The 709's transistorized successor, the IBM 7090, [3] had two to eight 6-bit channels (the 7607) and a channel multiplexor (the 7606) which could control up to eight channels.
The Ultra DMA (Ultra Direct Memory Access, UDMA) modes are the fastest methods used to transfer data through the ATA hard disk interface, usually between a computer and an ATA device. UDMA succeeded Single / Multiword DMA as the interface of choice between ATA devices and the computer.
What links here; Related changes; Upload file; Special pages; Permanent link; Page information; Cite this page; Get shortened URL; Download QR code
DMA is the only formal and predictable method for external devices to access RAM. This term is less common in modern computer architecture (above 66-100 MHz), where the various external buses and controllers generally run at different rates, and CPU internal operations are no longer closely coupled to I/O bus operations.