Typeahead is a feature of

computer A computer is a machine that can be Computer programming, programmed to automatically Execution (computing), carry out sequences of arithmetic or logical operations (''computation''). Modern digital electronic computers can perform generic set ...

s and

software Software consists of computer programs that instruct the Execution (computing), execution of a computer. Software also includes design documents and specifications. The history of software is closely tied to the development of digital comput ...

(and some

typewriter A typewriter is a Machine, mechanical or electromechanical machine for typing characters. Typically, a typewriter has an array of Button (control), keys, and each one causes a different single character to be produced on paper by striking an i ...

s) that enables users to continue typing regardless of program or computer operation—the user may type in whatever speed is desired, and if the receiving software is busy at the time it will be called to handle this later. Often this means that keystrokes entered will not be displayed on the screen immediately. This programming technique for handling uses what is known as a keyboard buffer. Typeahead has its roots in the age of typewriters. The

IBM Selectric typewriter The IBM Selectric (a portmanteau of "selective" and "electric") was a highly successful line of electric typewriters introduced by IBM on 31 July 1961. Instead of the "basket" of individual typebars that swung up to strike the ribbon and page ...

, first released in 1961, had a mechanical key lockout feature designed to smooth out typists' irregular keystrokes that, to many users, felt like typeahead. Achieving true typeahead requires maintaining a so-called "typeahead

buffer Buffer may refer to: Science * Buffer gas, an inert or nonflammable gas * Buffer solution, a solution used to prevent changes in pH * Lysis buffer, in cell biology * Metal ion buffer * Mineral redox buffer, in geology Technology and engineeri ...

"—a FIFO queue, for instance—whose role it is to store a limited amount of keyboard input until it is called for. Installing such a buffer can be done at both the hardware and the

levels; most modern operating systems, such as

Unix Unix (, ; trademarked as UNIX) is a family of multitasking, multi-user computer operating systems that derive from the original AT&T Unix, whose development started in 1969 at the Bell Labs research center by Ken Thompson, Dennis Ritchie, a ...

, implement this using software, calling kernel

interrupt In digital computers, an interrupt (sometimes referred to as a trap) is a request for the processor to ''interrupt'' currently executing code (when permitted), so that the event can be processed in a timely manner. If the request is accepted ...

s. In some network operations, one might attempt to dispatch information over a network, regardless whether the receiving program manages to keep up, using the recipient's typeahead functions. However, as this is far too reliant on the specifications of the computer with which one is communicating, it is not often used.

References

{{Reflist Typing User interface techniques

See also

References