Touch-typable devices based on ambiguous codes and methods to design such devices

The design of typable devices, in particular, touch-typable devices embodying ambiguous codes, presents numerous ergonomic problems. Solutions for these problems are herein disclosed. This invention teaches methods for the selection of ambiguous codes from the classes of strongly-touch-typable ambiguous codes and substantially optimal ambiguous codes for touch-typable devices such as computers, telephones, pagers, personal digital assistants, smart cards, television set-top devices and other information appliances, given design constraints such as the size, shape, and computational capacity of the device, the typical uses of the device, and conventional constraints such as respect of alphabetic ordering or Qwerty ordering.