Epson 500 Series User Manual

If you are typing for extended periods of time, you may want to

connect an external keyboard to the KB on your computer.

Although the KB and MOUSE ports look the same, they cannot be
used interchangeably. Be sure to plug your keyboard into the KB

port to avoid damaging your system. You can use any keyboard

with a PS/2-compatible connector.

You case use the MOUSE port to  connect the trackball or any

PS/2-compatible mouse or pointing device. See Chapter 1 for

instructions. The KB and  MOUSE ports cannot be used

interchangeably. Be sure to plug  your pointing device into the

MOUSE port.