Chapter 2
Hardware Configuration and Installation
© National Instruments Corp.
2-13
AT-GPIB for SCO UNIX
DMA Channel Selection
The AT-GPIB board is set at the factory to use DMA channel 5 (see
Figure 2-1 for the DMA channel location). The DMA channels supported
by the AT-GPIB board are channels 5, 6, and 7. If you install more than
one AT-GPIB board in your computer, each board must be configured to
use a unique DMA channel. The default AT-GPIB DMA channels for the
NI -488M software are shown in Table 2-7. You must change the DMA
channel setting on the hardware to match the software DMA channel
setting.
Table 2-7. Software Default AT-GPIB DMA Channel
Board
Default
DMA Channel
First AT-GPIB (
gpib0
)
7
Second AT-GPIB (
gpib1
)
6
Check to determine that the software default DMA channel setting is not
already used by other equipment in your computer. If any equipment in
your computer uses this DMA channel, change the DMA channel of either
the AT-GPIB or the other device.
Note :
DMA channels 5, 6, and 7 are the three 16-bit channels on the
PC AT I/O channel. The AT-GPIB board does not use and
cannot be configured to use the 8-bit DMA channels on the
PC AT I/O channel.
