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In computing, bus mastering is a feature supported by many bus architectures that enables a device connected to the bus to initiate direct memory access (DMA) transactions. It is also referred to as first-party DMA , in contrast with third-party DMA where a system DMA controller actually does the transfer.
A posted write is a computer bus write transaction that does not wait for a write completion response to indicate success or failure of the write transaction. For a posted write, the CPU assumes that the write cycle will complete with zero wait states, and so doesn't wait for the done. This speeds up writes considerably.
Being message-based (at the PCI Express layer), this mechanism provides some, but not all, of the advantages of the PCI layer MSI mechanism: the 4 virtual pins per device are no longer shared on the bus (although PCI Express controllers may still combine legacy interrupts internally), and interrupt changes no longer inherently suffer from race ...
PCI Express Mini Card (also known as Mini PCI Express, Mini PCIe, Mini PCI-E, mPCIe, and PEM), based on PCI Express, is a replacement for the Mini PCI form factor. It is developed by the PCI-SIG . The host device supports both PCI Express and USB 2.0 connectivity, and each card may use either standard.
One of the major improvements the PCI Local Bus had over other I/O architectures was its configuration mechanism. In addition to the normal memory-mapped and I/O port spaces, each device function on the bus has a configuration space, which is 256 bytes long, addressable by knowing the eight-bit PCI bus, five-bit device, and three-bit function numbers for the device (commonly referred to as the ...
In a PCI Express (PCIe) system, a root complex device connects the CPU and memory subsystem to the PCI Express switch fabric composed of one or more PCIe or PCI devices. A root complex is sometimes referred to PCI root bridge. [2] The root complex generates transaction requests on behalf of the CPU, which is interconnected through a local bus ...
Peripheral Component Interconnect (PCI) [3] is a local computer bus for attaching hardware devices in a computer and is part of the PCI Local Bus standard. The PCI bus supports the functions found on a processor bus but in a standardized format that is independent of any given processor 's native bus.
Each DMA transaction can transfer between 1 and 128 bytes between a memory buffer and the UART. PCI Express variants can also allow the CPU to transfer data between itself and the UART with 8-, 16-, or 32-bit transfers when using programmed I/O. 16C954 16C1550/16C1551: UART with 16-byte FIFO buffers. Up to 1.5 Mbit/s. The ST16C155X is not ...