IBM 5155 Manual To Operations page 247

20
Install the safety protector on the coprocessor as
shown below. Make sure the notch in the safety
protector is on the same end as the notch in the
coprocessor. The overlapped portions of the
safety protector should be on the bottom or pin
side of the coprocessor.
Coprocessor
Notch
Pin Side Of
Coprocessor
Overlapped Side Of
Safety Protector
Option Installation 4-19