Epson Progression U12 - Manual (Page 86)

Replacing the CPU Card
The components for your computer’s microprocessor are
contained on the CPU card installed inside the computer. This
allows you to easily upgrade your system by replacing the CPU
card with a faster one. There are three cards available for your
computer:
486SX/25
486DX/33
486DX2/66.
The instructions in this section describe how to remove the card
installed in your computer and install a new one. You also need
to perform these procedures if you want to install an OverDrive
module or a math coprocessor on the CPU card.
Installing and Removing Options 3-17