Appendix C
Changing Hardware Configuration Settings
© National Instruments Corp.
C- 3
AT-GPIB/NI-488M/AT&T UNIX
Table C-2. Software Default AT-GPIB Base I/O Addresses
Board
Default
Base I/O Address
First AT-GPIB (gpib0)
2C0 hex
Second AT-GPIB (gpib1)
240 hex
Check to determine that the software default I/O address space is not
already used by other equipment installed in your computer. If any
equipment in your computer uses this I/O address space, change the base
I/O address of the AT-GPIB.
Each switch in U25 corresponds to one of the PC AT bus address lines A9
through A5. The top switch (1) corresponds to address line A9, the next
switch from the top (2) corresponds to address line A8, and so on. The five
least significant bits of the address (A4 through A0) are used by the
AT-GPIB to select the appropriate GPIB adapter register and cannot be
changed; therefore, bits A4 through A0 are always 00000 (binary) when
determining the base I/O address.
Press down on the side of the switch marked 1 to select a binary value of 1
for the corresponding address bit. Press down on the side marked 0 to
select a binary value of 0 for the corresponding address bit (refer to Figure
C-2).
Figure C-2 shows two possible switch settings. In this figure, the black side
of the switch is the side you press down. Each of the address selections
shows how the base I/O address was calculated from the switch positions.