Hardware Reference
In-Depth Information
to as a
PS/2 mouse interface
. This term does not imply that such a mouse can work only
with a PS/2; instead, it means the mouse can connect to any system that has a dedicated
mouse port on the motherboard.
From a hardware perspective, a motherboard mouse connector is usually the same as the
mini-DIN connector used for keyboards. In fact, the motherboard mouse port is connec-
ted to the 8042-type keyboard controller found on the motherboard. All the PS/2 com-
puters include mini-DIN keyboard and mouse port connectors on the back. Most com-
puters based on the semiproprietary LPX motherboards and all ATX-series motherboards
use these same connectors for space reasons. Most Baby-AT motherboards have a pin-
header-type connector for the mouse port because most standard cases do not have a pro-
vision for the mini-DIN mouse connector. If that is the case, an adapter cable is usually
supplied with the system. This cable adapts the pin-header connector on the motherboard
to the standard mini-DIN type connector used for the motherboard mouse.
Figure 15.11
shows a PS/2 mouse connector.
Figure 15.11
Typical PS/2-type mouse connector.
Caution
As mentioned in the
“
Keyboard/Mouse Interface Connectors
” section earlier in this chapter,
the mini-DIN sockets used for both keyboard and mouse connections on many systems are
physically and electrically interchangeable, but the data packets they carry are not. Be sure
to plug each device into the correct socket; otherwise, neither will function correctly. Don't
panic if you mix them up, though. They are electrically identical to each other, so you can't
damage the ports or the devices.
Connecting a mouse to the built-in mouse port is the best method of connection on sys-
tems that don't have USB ports because you do not sacrifice any of the system's interface
slotsoranyserialports,andtheperformanceisnotlimitedbytheserialportcircuitry.The
standard resource usage for a motherboard (or PS/2) mouse port is IRQ12, as well as I/O
