Epson EQUITY 386/33 PLUS - Manual (Page 84)

Carefully follow these steps to install a math coprocessor:
1. Remove the computer’s cover and subassembly as described
in Chapter 3.
2. Remove the math coprocessor from its package and set it
aside.
3. The math coprocessor socket on the main system board is
square and has three rows of pins on each side. It has a
notch in the lower left corner, as shown below.
notch
The math coprocessor also has a notch in one corner, marked
by a dot, as shown below.
notch
l
4-24 Installing and Removing Options