<P> There are several ways of connecting a keyboard to a system unit (more precisely, to its keyboard controller) using cables, including the standard AT connector commonly found on motherboards, which was eventually replaced by the PS / 2 and the USB connection . Prior to the iMac line of systems, Apple used the proprietary Apple Desktop Bus for its keyboard connector . </P> <P> Wireless keyboards have become popular for their increased user freedom . A wireless keyboard often includes a required combination transmitter and receiver unit that attaches to the computer's keyboard port . The wireless aspect is achieved either by radio frequency (RF) or by infrared (IR) signals sent and received from both the keyboard and the unit attached to the computer . A wireless keyboard may use an industry standard RF, called Bluetooth . With Bluetooth, the transceiver may be built into the computer . However, a wireless keyboard needs batteries to work and may pose a security problem due to the risk of data "eavesdropping" by hackers . Wireless solar keyboards charge their batteries from small solar panels using sunlight or standard artificial lighting . An early example of a consumer wireless keyboard is that of the Olivetti Envision . </P> <P> 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). In other words, to convert the text from an image to editable text (that is, a string of character codes), a person could re-type it, or a computer could look at the image and deduce what each character is . OCR technology has already reached an impressive state (for example, Google Book Search) and promises more for the future . </P> <P> Speech recognition converts speech into machine - readable text (that is, a string of character codes). This technology has also reached an advanced state and is implemented in various software products . For certain uses (e.g., transcription of medical or legal dictation; journalism; writing essays or novels) speech recognition is starting to replace the keyboard . However, the lack of privacy when issuing voice commands and dictation makes this kind of input unsuitable for many environments . </P>

The numeric keys on the keyboard are sometimes called the ten keypad