Programmable calculator including means for permitting data entry during program execution

摘要

An adaptable programmable 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, an input-output control unit for 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 keyboard input unit a magnetic card reading and recording unit, a solid state display unit capable of displaying every alphabetic and numeric charater and many 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. A data entry statement may be programmably employed to halt execution of a program by the calculator to permit the user to enter one or more items of data, following which the data is automatically stored in a register or registers specified in the data entry statement. One of a plurality of flags internal to the calculator is set if the user calls for resuming execution of a program whose execution has been halted to permit the entry of data, if no data is entered by the user, thus permitting termination of the entry of successive items or data, the exact number of which is unknown at the time the program is written.