Epson 486SX - Manual (Page 88)

Using Expanded Memory Beyond 640KB
Your computer comes with 4MB of random access memory.
MS-DOS and your application programs that run under
MS-DOS use the first 640KB of memory. You can use the
unused memory above 640KB as extended memory, or you can
convert it to expanded memory, as described below.
Expanded memory is used by application programs (such as
Lotus® 1-2-3®) that support the Lotus/Intel/Microsoft
Expanded Memory Specification (LIM 4.0 EMS). To take
advantage of expanded memory, you need to use a memory
management program to convert the computer’s extended
memory to expanded memory.
If you selected a memory management software package when
you bought your computer, you can use it with any version of
MS-DOS. Just follow the instructions included with the package.
If you are using MS-DOS version 4.01 or 5.0 and you did not
get a memory manager, you can use the MS-DOS program
EMM386.SYS or EMM386EXE (respectively) to convert your
extended memory to expanded memory. See your MS-DOS
manuals for instructions.
If you are using MS-DOS version 3.3 and you did not get a
memory manager, ask your authorized Epson dealer which
expanded memory manager program you should use.
4-12 Enhancing System Operations