i) A logical input device is an abstraction of a number of physical input devices. For instance, text entry is a logical input function that can be implemented by a keyboard, speech recognition, cursive recognition on a stylus based system etc. This distinction offers considerable support for the development of device ?independent? interface

ii) Distinguish between formative and summative evaluation.

Formative evaluation helps to form design decisions while summative evaluation is often used at the end of development to demonstrate that requirements have been met. Formative evaluation is often low cost with the assumption that resources will be available to address any problem identified. Summative evaluation techniques involve a higher cost and there may not be sufficient resources or time to correct major design problems. Formative evaluation often relies on only a partial implementation while summative techniques may require a full system etc?