Hardware Reference
In-Depth Information
Many keyboard manufacturers have standardized on keyboards that include these Windows-specific
keys. Some manufacturers have added extra browser control or other keys that, although not standard,
can make them easier to use for navigating web pages and launching various applications.
Foreign-language versions of the Windows keyboard include a slightly different layout from the U.S.
versions.
Keyboard Technology
The technology that makes up a typical PC keyboard is interesting. This section focuses on all the
aspects of keyboard technology and design, including the keyswitches, the interface between the
keyboard and the system, the scan codes, and the keyboard connectors.
Keyswitch Design
Today's keyboards use any one of several switch types to create the action for each key. Most
keyboards use a variation of the mechanical keyswitch. A mechanical keyswitch relies on a
mechanical momentary contact-type switch to make the electrical contact that forms a circuit. Some
high-end keyboards use a more sophisticated design that relies on capacitive switches. This section
discusses these switches and the highlights of each design.
The most common type of keyswitch is the mechanical type, available in the following variations:
• Pure mechanical
• Foam element
• Rubber dome
• Membrane
• Touch
Pure Mechanical Switches
The pure mechanical type is just that—a simple mechanical switch that features metal contacts in a
momentary contact arrangement. The switch often includes a tactile feedback mechanism, consisting
of a clip and spring arrangement designed to give a “clicky” feel to the keyboard and offer some
resistance to the keypress (see
Figure 15.2
).
