Screen-Oriented Input and Output

Sequential input and output implies that elements of data can be transmitted without explicit indication of position. This is natural, if the position is predetermined by the storage medium, such as a tape (which by definition constitutes a sequence), or a keyboard (from which data originate in strict sequence in time), or a typewriter (where character positions are determined by the mechanical movement of the printing device). Even if the storage device would allow for greater flexibility, sequential input and output is convenient, if the structure of the data is inherently sequential. For example, a text is inherently sequential, and the omission of positioning information for each character is a great simplification of the reading and writing tasks. And lastly, sequential input and output is economical, because buffering of data is easily possible between processes (devices) that operate concurrently. All this explains, why sequential data handling is so common and highly recommendable.