As opposed to the usual type of short statements interchanged between the users and the computer in the present time-shared computer operations a library user frequently will require a large quantity of data to be sent to him so that he might scan through it. On the other hand, the library user will spend most of his central processor time on generating search specifications rather than generating programs or nu- merical data.
A library continually receives new acquisitions and library procedures change from time to time. Hence, the augmented-catalog display console must be able to evolve and gracefully accept various types of changes with a minimum of disruption to library services and at a minimum cost.
Since a computer-based library will operate for a long period of time before being replaced, cost of ownership, which not only includes original cost but recurring costs of such items as maintenance, communi- cations and updating, is of great importance.