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The PS/2 mouse port is a great addition to the standard port configuration of Toshiba's more recent lines of computers. One of the greatest benefits of this dedicated mouse port is that it frees up the serial port for other uses.
A PS/2 mouse has all the features of a serial mouse, but a PS/2 mouse port is not an RS232 serial port so PS/2 mouse users should be aware that a PS/2 mouse port is not *always* a direct replacement for a serial port, for every mouse and mouse driver combination.
Let's first look at the main difference between a PS/2 mouse port and a serial port, then at some possible compatibility problems, and finally a look at some unique features of the Toshiba QuickPort BallPoint mouse.
A PS/2 PORT IS NOT A SERIAL PORT
Since some serial pointing devices can be used on PS/2 ports (with adapter cables), it may *appear* that there's no difference between a PS/2 port and a serial port, except for the shape and size of the connector. However this is not the case. There is one very significant difference. PS/2 MOUSE PORT IS ONLY INITIALIZED WHEN A PS/2 MOUSE IS CONNECTED TO IT AS THE COMPUTER BOOTS. If a PS/2 mouse is not connected to the port when the system boots, then the PS/2 port is not initialized and a mouse driver will not be able to find a mouse, even though one may later be connected to the PS/2 mouse port.
Remember that if AutoResume is in use, the computer does not reboot when turned on. So, if a PS/2 mouse is connected *after* the system has booted (although it may be connected before the system is turned on for a given work session) the system must be rebooted (Ctrl+Alt+Del) before the port will be initialized and before a mouse driver can be successfully loaded.
This leads to another difference between a serial port and a PS/2 mouse port. The RS232 specification for serial ports is extremely hardy and conservative towards protection against any possible damage when "hot" connecting or disconnecting (while the power is on) RS232 compatible devices. This is not the case with the standard PS/2 mouse port (as opposed to the QuickPort, as explained below) and care should be given
*not* to connect or disconnect a PS/2 mouse while the computer is turned on. Failure to abide by this simple but important rule can result inunnecessary down time and need of a potentially costly repair.
For the more technically oriented, the PS/2 mouse port uses IRQ 12.
POSSIBLE COMPATIBILITY PROBLEMS
1. Not every serial mouse can be used as a PS/2 mouse.
Most vendors of serial pointing devices have made serial-to-PS/2
adapters and supported these devices, and their own `native' PS/2
pointers with software drivers. _However_, this isn't always the
case with every vendor; and some vendors support some of their
devices for use with PS/2 adapters, but not all of them.
2. Not every serial mouse which can be used with a serial-to-PS/2
adapter will work with every adapter cable.
e.g. - I picked up a serial-to-PS/2 adapter from a local computer
"superstore", only to find out that this particular adapter did not
work with my Microsoft serial mouse, even though the same mouse with
the same driver software worked fine with a Microsoft serial-to-PS/2
adapter.
3. Some serial pointing devices that will work fine on PS/2 ports with
the appropriate adapter will require a driver upgrade.
Check with your mouse vendor to make sure your pointer can be used
on PS/2 ports. If it can be, verify that you have an adapter that
is known to work with it and that your driver software is an
appropriate version.
THE QUICKPORT BALLPOINT (A.K.A. DCBP OR DIRECT CONNECT BALLPOINT)
In our never ending search for ergonomic excellence mixed with
painstakingly pacesetting practicality, Toshiba and Microsoft
co-developed the QuickPort BallPoint device. Based on Microsoft's
popular BallPoint, the QuickPort version of this pointer replaces the
cable and connector with a "direct connect" interface using spring
loaded pins contacting an array of five contacts on the side of the PC.
The electrical and mechanical connections are seamless. The QuickPort
BallPoint is essentially a PS/2 mouse with an interface specialized for
use on portable PC's.
Removing the cable to provide an quick and easy clamp-on pointer was not
enough, though. What was also needed was a modification to the mouse
driver software which would allow the QuickPort BallPoint to be
disconnected and reconnected in the middle of a work session. This
"persistent" mouse driver allows a user to start a session with the
QuickPort connected, resume a work session without the QuickPort
connected, then hook it up later and continue using it with no risk of
damage to the hardware. This is not recommended with a standard PS/2
mouse port and may even damage the hardware of a standard PS/2 mouse
port. This robust hardware and software enhancement brings added ease
of use to mobile computing using AutoResume with or without a mouse
connected, without the need to reboot between sessions.
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All of the above information is accurate to the best of my finite
knowledge. If you would take issue with any of these points, please
address your comments via CompuServe email to Jim Rohrer [76702,1300].