Epson EL 486UC - Manual (Page 58)

Installing Memory Modules (SMMs)
Your computer comes with 4MB of memory on a SIMM. By
installing additional SIMMs, you can increase the amount of
memory in your computer up to 64MB.
There are two SIMM sockets on the main system board. You
can install 4MB, SMB, 16MB, and 32MB SIMMs. The following
table shows the possible SIMM configurations; do not install
memory in any other configuration. (When the front of the
computer is facing you, BANK 0 is on the right. An x in the
table below indicates no SIMM installed .)
3MM configurations
4-10 Installing and Removing Options