IBM RT PC Options Installation page 58

Use the following steps to install the fixed-disk drive in position D:
1. Remove the cooling fan assembly. See "Cooling Fan Removal" on
page 2-6.
Warning: Do not bend the pins!
2. Remove the terminating resistor by pulling the paper tab, if present, or
inserting a small, flat-bladed screwdriver under the resistor. Carefully
lift, alternating ends of the resistor to lift evenly.
3. Check the drive selection jumper or switches for the correct setting.
------
Drive
Selection
Jumper
/
Setup
--
Off On
1 X
2
3
4 X
/
Setup Switches
Section 2. Removing and Installing Drives in
mM
6150
2-21