Chapter 3
Hardware Overview
©
National Instruments Corporation
3-5
PCI/PXI-1408 and NI-IMAQ for Win95/NT
Scatter-Gather DMA Controllers
The PCI/PXI-1408 uses three independent onboard direct memory
access (DMA) controllers. The DMA controllers transfer data between
the onboard first-in first-out (FIFO) memory buffers and the PCI bus.
Each of these controllers supports scatter-gather DMA, which allows
the DMA controller to reconfigure on-the-fly. Thus, the 1408 device
can perform continuous image transfers to either contiguous or
fragmented memory buffers.
PCI Interface
The 1408 device implements the PCI interface with a National
Instruments custom application-specific integrated circuit (ASIC), the
PCI MITE. The PCI interface can transfer data at a maximum rate of
132 Mbytes/s in master mode, which maximizes the available PCI
bandwidth. 1408 devices can generate 8-, 16-, and 32-bit memory read
and write cycles, both single and multiple. In slave mode, the 1408
device is a medium speed decoder that accepts both memory and
configuration cycles. The interface logic ensures that the 1408 device
meets the loading, driving, and timing requirements of the PCI
specification.
Board Configuration NVRAM
The 1408 device contains onboard nonvolatile RAM (NVRAM) that
configures all registers on power-up.
