American Megatrends 42 Series User Manual page 22

Step 3 Install Coprocessor,
Continued
Installing a Cyrix or Intel coprocessor on the Motherboard
An Intel 80387 or Cyrix 83D87 coprocessor will fit in the Weitek 121-pin PGA socket. The 80387 and 83D87 are 64-pin PGA-
mount coprocessors. Surface-mount coprocessors will not work.
When installing the Cyrix or Intel coprocessor, align pin 1 as described for the Weitek (remember, the chamfered edge is on
the bottom of the coprocessor), and insert the coprocessor in the center of the socket, leaving the outer set of pin sockets
empty. See the figures on the following page.