Epson EL 486UC - Manual (Page 59)

Use only tin-plated, 32-bit or 36-bit, 72-pin, fast-page mode
SIMMs that operate at an access speed of 70ns (nanoseconds) or
faster.
Be sure all the SIMMs operate at the same speed.
Inserting SIMMs
Make sure the computer is turned off and then follow these
steps to install SIMMs:
1. Make sure the front of the computer is facing you.
2. Refer to the illustration on page 4-5 to locate the SIMM
sockets on the right side of the system board.
3. Remove any option cards that may be blocking your access
to the SIMM sockets. (See page 4-18 for instructions.)
4. Position the SIMM at an angle over the empty SIMM socket,
as shown below.
Installing and Removing Options 4-11