IBM RT PC Options Installation page 159

The jumpers on this adapter can be set to either interrupt level 3
or 9. If you have the IBM PC Enhanced Graphics Adapter or the
IBM Personal Computer 3278/79 Emulation Adapter, ensure that
the interrupt level on the IBM PC Network Adapter is set to 3, since
these other two adapters use 9. To set the interrupt level to 3, set
jumper W4 as shown. To set the interrupt level to 9, set the same
jumper (called W3 when set at 9) as shown in the illustration below.
Note: See Installing and Customizing the AIX Operating System
for additional information about interrupt conflicts. Also see
"Adapter Conflicts" on page 1-19.
Installing: You can install this adapter in slots 2 through 8 in IBM
6150 and in slots 1 through 5 in IBM 6151, whichever is available.
See the system unit diagram for the correct adapter slot.
In IBM 6151, you can more easily connect cables if you install the
adapter in a slot other than adapter slot 1.
Section 6. Communication and Network Adapter Options 6-11