Typeahead is a feature of

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

s and

software Software is a set of computer programs and associated documentation and data. This is in contrast to hardware, from which the system is built and which actually performs the work. At the lowest programming level, executable code consists ...

(and some

typewriter A typewriter is a mechanical or electromechanical machine for typing characters. Typically, a typewriter has an array of keys, and each one causes a different single character to be produced on paper by striking an inked ribbon selectivel ...

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 A keyboard buffer is a section of computer memory used to hold keystrokes before they are processed. Keyboard buffers have long been used in command-line processing. As a user enters a command, they see it echoed on their terminal and can edit i ...

. Typeahead has its roots in the age of typewriters. The

IBM Selectric typewriter The IBM Selectric typewriter 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 in a typical typewriter of the perio ...

, 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 * Buffering agent, the weak acid or base in a buffer solution * Lysis buffer, in cell biology * Metal ion buffer * ...

"—a FIFO queue, for instance—whose role it is to store a limited amount of

keyboard Keyboard may refer to: Text input * Keyboard, part of a typewriter * Computer keyboard ** Keyboard layout, the software control of computer keyboards and their mapping ** Keyboard technology, computer keyboard hardware and firmware Music * Musi ...

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, multiuser 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, and ot ...

, implement this using software, calling

kernel Kernel may refer to: Computing * Kernel (operating system), the central component of most operating systems * Kernel (image processing), a matrix used for image convolution * Compute kernel, in GPGPU programming * Kernel method, in machine learnin ...

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 Network, networking and networked may refer to: Science and technology * Network theory, the study of graphs as a representation of relations between discrete objects * Network science, an academic field that studies complex networks Mathematics ...

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