Epson 486SX - Manual (Page 184)

Memory Module Problems
If you added extra memory to your system by installing SIMMs
and that memory is not operating properly, check the following:
1. Check to make sure that you set the memory configuration
jumpers (JP8 through JP14) correctly and that they match
your current SIMM configuration. See Chapter 6 for
instructions on setting memory jumpers.
2. If the jumpers are set correctly but the memory count
displayed by the power-on diagnostics program is
incorrect, you or your dealer may not have installed the
SIMMs correctly. They may be installed in the wrong
sockets, they may be the wrong type of SIMM, or they may
not be inserted all the way. (Keep in mind that the memory
count does not include the 384KB of memory between
640KB and 1MB.)
If your dealer installed the SIMMs for you, contact your
dealer; do not attempt to correct the problem yourself. If
you installed the SIMMs, see “Memory Modules” in
Chapter 6 and make sure you have followed all the
instructions properly.
3. Be sure to run the Setup program after you install or
remove memory modules to automatically update your
memory configuration. See Chapter 2 for instructions.
If you still have trouble with your SIMMs, write down any
error messages that appear and contact your dealer.
Troubleshooting B-29