IBM 5155 Manual To Operations page 253

27
You must set a system board switch to reflect
the installation of the IBM Math Coprocessor
Option. Study the figure below. There are two
types of switch blocks on the system board:
rocker switch block and slide switch block.
Identify the type of switches on your system
board. Set Switch 2 to the Off position.
Ballpoint
Do you have another internal option to install?
YES ­ Go to Step 17.
NO ­ Make sure you set your system board
switch, then go to Step 62 to install your
covers.
Option Installation 4-25