Comptuer Keyboards

Today in class we got a project on The Keyboard. These are some notes on the computer keyboard:

Keyboard Introduction:

The original design for keyboards came from mechanical typewriters. A keyboard’s main function is to act as an input device. Keyboards use switches and circuits to translate keystrokes into signals that the computer can understand. Keyboards can be used to type a document, use keystroke shortcuts, access menus and play games. Most keyboards have between 80 and 110 keys. Although keyboards can have different keys depending on the manufacturer, most keyboards have keys that are the same size and shape.

Keyboard Arrangements:

The layout for most keyboards is known as QWERTY, the same original pattern used for typewriters. The reason it's layed out this way is because when the first typewriters were invented they put the most common letters in hard to reach places so that the metal arms wouldn't keep crashing into each other. Since then, it's been a standard for keyboards. There are some other arrangements such as the Dvorak arrangement. Some people argue that the Dvorak increases typing speed and effiency. However, it's almost the same speed for all keyboard arrangements.

How It Works:

A keyboard has its own processor and a circuitry to carry information to and from the processor. The key matrix is a grid of circuits underneath the keys. Each circuit is broken at a point below the key so when you press a key it completes a circuit and allows some current to flow through. When the processor finds a closed circuit, it matches it with a character map found in its read-only (ROM) memory. This character map tells the processor the position of each key and what combinations of keystorkes represent. Then it sends the information to the computer. Keyboards connect to the computer using a PS/2 or USB connection. The computer’s keyboard controller processes the information and sends it to the operating system. The operating system checks if it is a system level command. If it's not then the information is seen as content (i.e. typing a document) and then sends it to the current application. If the current application does not accept the data then the computer ingores the information. This whole process happens almost instantly.

Ergonomic Keyboards:

Some people say that repeated use of the keyboard can cause injuries like carpal tunnel syndrome. To address this issure ergonomic keyboards were invented to keep the hands in a more "natural" postion when typing. However people still debate on whether or not this pevents injury.