Historical note: The QWERTY layout is a fine example of a fossil. It is sometimes said that it was designed to slow down the typist, but this is wrong; it was designed to allow faster typing --- under a constraint now long obsolete. In early typewriters, fast typing using nearby type-bars jammed the mechanism. So Sholes fiddled the layout to separate the letters of many common digraphs (he did a far from perfect job, though; `th', `tr', `ed', and `er', for example, each use two nearby keys). Also, putting the letters of `typewriter' on one line allowed it to be typed with particular speed and accuracy for demos. The jamming problem was essentially solved soon afterward by a suitable use of springs, but the keyboard layout lives on.
