Original keyboards were made with 84 keys. Later, a version of keyboard known as the enhanced keyboard raised the keycount to 101. Windows 104 key keyboards are the most common now, and add buttons that were made to work specifically in Windows operating system.

Early keyboards where attached by an oversized connector called a DIN. This was replaced by what most computers use today, called a PS/2 port. Some newer keyboards are starting to use the USB interface.

Mice operate by sensing a ball under the outer shell. There are two scroll-wheels which brush up on this ball when the ball rolls, tracking its X and Y movements. Some newer mice do not use a ball anymore, rather they use a high speed camera underneith the shell, and this camera constantly takes of the surface below. By analysing these pictures, the mouse can detect which way the mouse has moved.

Connectors
Early mice used the standard serial port of the computer. With the advancement of the PS/2 port, most mice are no longer connected to the serial port. Some newer mice are now being connected via the USB bus, which seems to be the trend of the future.