Programmable calculator including keyboard functions whose argument may be a numeric constant, a storage register, or an arithmetic expression

摘要

An adaptable programable calculator is provided by employing modular read-write and read-only memory units 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, 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. The memory, central processor, and input-output control units are controlled by a microprocessor included in the central processing unit. The input and output units include a keybord input unit with a plurality of sections capable of being defined by plug-in read-only memory modules and stored programs added by the user, a magnetic card reading and recording unit capable of bidirectionally transferring information between an external magnetic card and the calculator, a solid state display unit capable of displaying every alphabetic and numeric character and may other symbols individually and in a line of one or more alphameric statements, and a printer unit capable of printing on thermally sensitive paper every alphabetic and numeric character and many other symbols individually and in alphameric statements or messages. The keyboard input unit may be employed by the user to enter functions to be evaluated by the calculator. Such functions may specify an argument that is a real constant, the contents of a specified storage register within the read-write memory, or an algebraic expression.