When it comes to Computer Repairs Penrith, a common method involves the connection to the serial port (RS232) over a nine – or 25-pin D sub connector. This serial interface was originally designed for data transmission with teletypes, modems and acoustic couplers.

Since the mouse is a simple and slow in data transfer device that only coordinates information and status of the keys, its power could be obtained from the interface using this repurposed handshake pins. This interface was quite a durable solution in which the mouse can also be connected without downtime.

This serial solution remained on PCs since the mid-980s, for more than ten years and disappeared as from 1996 only gradually with the advent of ATX motherboards.

Proprietary interfaces

Early Apple computer models of the Apple II series were still designed without a mouse. For these, only a Busmouse concept came with a special plug-in card for the mouse connector.

For the original Macintosh, Macintosh 512 and Macintosh Plus, the unprocessed signals of the axes and the key on a nine-pin D sub-connector were transferred, replaced in the Macintosh II and Macintosh SE by the more universal Apple Desktop Bus (ADB ) in 1987.

With the ADB, the mouse is connected to the keyboard and the keyboard to a second ADB to the computer. Also other small devices are connected via ADB. The ADB was used until the Power Macintosh G3 in 1998, at the Apple ADB replaced by the USB interface.

Even with SUN Unix workstations, the mouse was connected to with the keyboard until about 2003, and both devices are connected to a common cable to the workstation (SUN Ultra).


With the wide advent of mouse-driven operating systems with the PS/2-connector, IBM compatible computers used a separate interface for the mouse. This had already been defined in 1987 by IBM in the technical reference manuals for PS/2-System. The transmission protocols and pinouts of the keyboard and mouse are identical.

It is a synchronous serial protocol that was originally designed for computer – keyboard and operates on a 5 volt power supply. The PS2 format is different than the serial and the USB port because it is not hot-pluggable: A mouse must already be connected to it when the computer is to be used. A unplugging during operation results in problems and can even destroy the interface.

USB interface

Today, the universal USB port for mice and other peripherals for IBM – compatible computers, Unix workstations (SUN, IBM), and for Apple Macintosh computers is becoming more common beside the PS/2-connector. For transmission, in addition to the mass and 5V power supply line, two data lines are used to transmit differentially.