Acer SmartRAID V Bedienungsanleitung PDF herunterladen (Seite 193)

7-25

Theory of Operation

PCI Data Transfer and Bus Mastering

The Peripheral Component Interconnect (PCI) bus provides a means to

interconnect peripheral chips and expansion cards to the computer

backplane. PCI is optimized for peripheral device controllers that transfer

data in blocks. PCI allows for data transfer rates of 132MB/sec (32-bit PCI)

and 264MB/sec (64-bit PCI). If a Plug-and-Play BIOS is available,

automatic expansion card configuration is also available.

All SmartRAID V controllers use a PCI bus for internal communication as

well as their interface to the host computer. SmartRAID V Century

controllers are configured by the host BIOS as multifunction PCI devices.

SmartRAID V Millennium controllers are seen by the host computer as

standard PCI-to-PCI bridge devices. Millennium controllers are available

in both 32-bit and 64-bit PCI versions.

The PCI bus uses a 33MHz clock rate as opposed to the 8.33MHz clock

used by ISA and EISA buses. To maintain data integrity at the higher clock

rate, the PCI bus is limited to four card slots and six devices integral to the

motherboard. However, motherboard designs can include multiple PCI

buses that are interconnected through bridge devices.

PCI supports two modes of data transfer: Bus mastering and PIO. Third

party DMA is not supported by the PCI architecture.

Each PCI device contains configuration registers that allow the system to

be configured for maximized throughput. Parameters such as Latency

Timer, Cache Line Size, Minimum Bus Grant, Maximum Latency, as well

as configurable address and IRQs, can be read or written by the PCI

system BIOS. SmartRAID V controllers support the full range of required

and optional features described by revision 2.1 of the PCI specification.

SmartRAID V controllers are also fully compliant with revision 2.1 of the

PCI specification for bus drivers and receivers. These transceivers are

unique in their ability to vary the drive current in order to minimize signal

reflections.

All mandatory and optional memory read/write commands are supported

by SmartRAID V controllers. Mandatory commands include Memory

Read and Memory Write, which are used by all PCI bus-mastering devices.

Optional commands include Memory Read Line, Memory Read Multiple

and Memory Write and Invalidate. These commands maximize

performance in PCI systems with intelligent bridges that perform CPU

cache line optimization.

1 2 ... 188 189 190 191 192 193 194 195 196 197 198 ... 255 256

Keine Kommentare

Acer SmartRAID V Bedienungsanleitung Seite 193