Programmable calculator employing computed memory addresses

Abstract

An adaptable programmable calculator is provided by employing a modular read-write and read-only memory unit capable of being expanded to provide the calculator with additional program and data storage functions oriented towards the environment of the user, a central processing unit capable of performing both serial binary and parallel binary-coded-decimal arithmetic, and an input-output control unit capable of bidirectionally transferring information between the memory or central processing units and a number of input and output units, such as a keyboard and an output display unit. The memory, central processor, and input-output control units are controlled by a microprocessor included in the central processing unit. Data storage registers within the calculator memory may be addressed directly by the computed integral value of an arithmetic expression that may in turn incorporate the contents of one or more similarly addressed data storage registers, thus facilitating efficient fetching and storing of information, as well as matrix operations and manipulation of files. A plurality of dedicated data storage registers having fixed labels and locations within the calculator memory may, by single key actuations on the part of the user, be called into a displayed algebraic expression, the contents of which are then manipulated in accordance with the algebraic expression.