Chapter 2
Hardware Configuration and Installation
© National Instruments Corp.
2-17
AT-GPIB for SCO UNIX
If you change the hardware DMA channel to something other than 7, make
sure that you make a corresponding change to the software DMA channel as
described in Chapter 3, Software Installation and Configuration . Also,
make sure that you record the new setting on the AT-GPIB Hardware and
Software Configuration Form in Appendix D, Customer Communication.
Table 2-9 lists some of the DMA channels used by other PC AT plug-in
interface boards and adapters. This is by no means a complete list, but it
may help in determining possible DMA channel conflicts. Symptoms of
DMA channel conflicts vary widely. At one extreme, conflicts can prevent
the computer from booting. At the other extreme, DMA channel conflicts
can sometimes be detected quite easily, because any data transfer operation
(
ibrd
,
ibwrt
) will time out, with no bytes transferred.
National Instruments has made every effort to select a software default
DMA channel that will work. However, because of the numerous different
interface boards available for use in the PC AT, it is not possible to select a
DMA channel that is guaranteed to work in all systems.
Table 2-9. PC AT 16-Bit DMA Channel Assignment Map
Channel
Device
7
AT-GPIB board 0 (software default)
6
AT-GPIB board 1 (software default)
5
Adaptec SCSI Card
4
Cascade for DMA Controller # 1
(channels 0 through 3)