The classification and design of operation codes for automatic computers

A classification of the various possible logical arrangements for a computing machine is made in terms of the type of storage used and the mode of access to it which is provided. Among the possible machines is one which uses two separate storage systems for numbers and instructions, both systems being parallel random-access stores. Such a machine should be asynchronous in action, and it is suggested that the instruction store can be non-erasable. Consideration of the facilities required by a desk computer discloses certain desirable features the machine should possess, and a form of code is devised which meets these requirements. Further analysis of the special problems of automatic computing reveals other necessary facilities, and the logical structure of the machine implied by the above code enables these to be provided without difficulty. In particular, the problems of using library routines and the testing of programmes are solved in a manner which imposes the minimum of inconvenience to the programmer. This approach to the design of a computing machine is illustrated by reference to a simplified version of the code for the projected I.C.C.E. II under development at Imperial College.