Figure2.3 dma fifo sections, Dma fifo sections – LSI 53C875A User Manual

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Functional Description

Figure 2.3

DMA FIFO Sections

The LSI53C875A automatically supports misaligned DMA transfers. A
944-byte FIFO allows the LSI53C875A to support 2, 4, 8, 16, 32, 64, or
128 Dword bursts across the PCI bus interface.

2.2.12.1 Data Paths

The data path through the LSI53C875A is dependent on whether data is
being moved into or out of the chip, and whether SCSI data is being
transferred asynchronously or synchronously.

Figure 2.4

shows how data is moved to/from the SCSI bus in each of the

different modes.

118

Transfers

Deep

.
.

.

.
.

.

8 Bytes Wide

8 Bits

Byte Lane 7

8 Bits

Byte Lane 6

8 Bits

Byte Lane 5

8 Bits

Byte Lane 4

8 Bits

Byte Lane 3

8 Bits

Byte Lane 2

8 Bits

Byte Lane 1

8 Bits

Byte Lane 0

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