Since there are many combinations available, chorded keyboards can effectively produce more actions on a board with fewer keys. A wireless keyboard must have a transmitter built in, and a receiver connected to the computer's keyboard port; it communicates either by radio frequency (RF) or infrared (IR) signals. This is undesirable, especially for fast typing (hitting new keys before the fingers can release previous keys), and games (designed for multiple key presses). The Space bar is a horizontal bar in the lowermost row, which is significantly wider than other keys. It is possible to install multiple keyboard layouts within an operating system and switch between them, either through features implemented within the OS, or through an external application. Because the "keys" are simply projected images, they cannot be felt when pressed. Keystroke logging (often called keylogging) is a method of capturing and recording user keystrokes. Some Windows public terminals do not have a Menu key on their keyboard to prevent users from right-clicking (however, in many Windows applications, a similar functionality can be invoked with the Shift+F10 keyboard shortcut). In the beginning, keyboard keytops had a "dish shape" on top, like typewriters before them. Optical character recognition (OCR) is preferable to rekeying for converting existing text that is already written down but not in machine-readable format (for example, a Linotype-composed book from the 1940s). Another input device such as a mouse or a touchscreen can be used to operate each virtual key to enter text. In the first electronic keyboards in the early 1970s, the key switches were individual switches inserted into holes in metal frames.  The teleprinter, in its more contemporary form, was developed from 1907 to 1910 by American mechanical engineer Charles Krum and his son Howard, with early contributions by electrical engineer Frank Pearne. On another note, IBM was unique in using separate shells, or "keycaps", on keytop bases. In word processing applications, pressing the enter key ends a paragraph and starts a new one. Compact keyboard layouts often use a Fn key.  In a modern computer, the interpretation of key presses is generally left to the software: the information sent to the computer, the scan code, tells it only which key (or keys) on which row and column, was pressed or released.. Label F1, F2, F3, F4, F5, F6, F7, F8, F9, F10, F11 and F12. The numeric characters become symbols or punctuation marks when the shift key is depressed. The alphabetic characters become uppercase when the shift key or Caps Lock key is depressed. OCR technology has already reached an impressive state (for example, Google Book Search) and promises more for the future. In normal usage, the keyboard is used as a text entry interface for typing text, numbers, and symbols into application software such as a word processor, web browser or social media app. Modifier keys are special keys that modify the normal action of another key, when the two are pressed in combination. Wireless solar keyboards charge their batteries from small solar panels using natural or artificial light. Some specialized PC keyboards have 24 function keys, F1 through F24. Today, most full-size keyboards use one of three different mechanical layouts, usually referred to as simply ISO (ISO/IEC 9995-2), ANSI (ANSI-INCITS 154-1988), and JIS (JISX 6002-1980), referring roughly to the organizations issuing the relevant worldwide, United States, and Japanese standards, respectively. Alphabetical, numeric, and punctuation keys are used in the same fashion as a typewriter keyboard to enter their respective symbol into a word processing program, text editor, data spreadsheet, or other program. Analog keyboards with key switches whose activation distance can be reconfigured through software, optical switches that work by blocking laser beams, and Hall Effect keyboards that use key switches that use a magnet to activate a hall sensor, are also available. By using a touchpad or a stylus pen with a graphic tablet, in place of a mouse, one can lessen the repetitive strain on the arms and hands. How many function keys are on a keyboard? To resolve this problem, the processor in a keyboard (or computer) "debounces" the keystrokes, by aggregating them across time to produce one "confirmed" keystroke. Microsoft wireless keyboards 2011 and earlier are documented to have this vulnerability.. The alphabetical, numeric, and punctuation keys can also have other functions when they are pressed at the same time as some modifier keys. , This article is about keyboard technology, the hardware. Software keyboards or on-screen keyboards often take the form of computer programs that display an image of a keyboard on the screen. New generation multifunctional keyboards feature a touchscreen display to stream video, control audio visual media and alarms, execute application inputs, configure individual desktop environments, etc. For certain uses (e.g., transcription of medical or legal dictation; journalism; writing essays or novels) speech recognition is starting to replace the keyboard. Common environments for multifunctional keyboards are complex, high-performance workplaces for financial traders and control room operators (emergency services, security, air traffic management; industry, utilities management, etc.). In addition to this, Linux and variants, as well as many DOS programs, treat this combination the same as Ctrl+C. Multiple interfaces (serial, USB, audio, Ethernet, etc.) Computer keyboards include control circuitry to convert key presses into key codes (usually scancodes) that the computer's electronics can understand. This technology has also reached an advanced state and is implemented in various software products. Handheld ergonomic keyboards are designed to be held like a game controller, and can be used as such, instead of laid out flat on top of a table surface. Earlier, Herman Hollerith developed the first keypunch devices, which soon evolved to include keys for text and number entry akin to normal typewriters by the 1930s.  There was simply a sponge pad with a conductive-coated Mylar plastic sheet on the switch plunger, and two half-moon trace patterns on the printed circuit board below. Most commonly the emitters and sensors are located in the perimeter, mounted on a small PCB. Historically it also served as a type of shift key, such that one or more following characters were interpreted differently, hence the term escape sequence, which refers to a series of characters, usually preceded by the escape character. If the computer were watching for each pulse, it would see many keystrokes for what the user thought was just one. ESC was part of the standard keyboard of the Teletype Model 33 (introduced in 1964 and used with many early minicomputers). Keytops are an important element of keyboards. Function- and arrow keys are nearly always present. Microsoft Windows, Linux, and Mac provide support to add keyboard layouts and choose from them. Still, the basic PC keyboard layout has 104 keys common to all PC keyboards. Three final mechanical technologies brought keyboards to where they are today, driving the cost well under $10: Plastic materials played a very important part in the development and progress of electronic keyboards. The first keyboard microprocessor was introduced in 1972 by General Instruments, but keyboards have been using the single-chip 8048 microcontroller variant since it became available in 1978. Network monitors (also known as reverse-firewalls) can be used to alert the user whenever an application attempts to make a network connection. , The keyboard on the teleprinter played a strong role in point-to-point and point-to-multipoint communication for most of the 20th century, while the keyboard on the keypunch device played a strong role in data entry and storage for just as long.