A
mouse that connects to a
computer via an
expansion board. Another type of mouse is a
serial mouse, which connects to a
serial port.
Serial mice are easier to install, but the advantage of bus mice is that they do not use up the serial port, so you can use the
port for a different
device (a
modem, for example). A PS/2 mouse solves this problem by plugging into a special
PS/2 port dedicated to the mouse. Bus mice are now obsolete.