Epson Equity 286 PLUS - Manual (Page 31)

mouse connector
Caution
Although the mouse and keyboard connectors are physically
identical, they cannot be used interchangeably. Be sure to
insert the mouse plug into the mouse port.
Once you have connected a mouse, you may need to add
commands to your MS-DOS CONFIG.SYS file to enable your
computer to use a mouse. See your MS-DOS Reference Manual
and the manual that came with your mouse for instructions.
Note
If you want to use a mouse or other pointing device
connected to a port on an option card in your computer, you
can disable the built-in mouse connector by changing the
setting of jumper J4. See Chapter 5 for instructions.
1-14 Setting Up Your System