A Simple Row-replacement Method

Updating a video screen involves row replacement, i.e. the task of updating an existing screen row to produce the desired row. In many environments, screen operations require transmitting characters to the terminal by a process that is painfully slow compared to computing speeds. Thus, it is worth while to compute a minimal set of row updating commands, as long as the time to do so does not outweigh the savings in character transmission time. This paper presents a simple and practical algorithm for optimal row replacement and describes experience with its use in a screen editor.