Hewlett-packard Company

John H Nairn

Wayne F Covington

Chris J Christopher

Donald E Morris

Jeffrey C Osborne

Fred W Wenninger

Jerry B Folsom

Joseph W Beyers

An adaptable programmable calculator employs modular read-write and read-only memories separately expandable to provide additional program and data storage functions within the calculator oriented toward the environment of the user, and an LSI NMOS central processing unit, which includes the capability of bidirectionally transferring information between itself and various input/output units. The input/output units include a keyboard input unit having a full complement of alphanumeric keys, a magnetic tape cassette reading and recording unit capable of bidirectionally transferring programs and data between the calculator and a magnetic tape, a 32-character solid state output display unit capable of displaying every alphabetic and numeric character. The calculator employs a natural algebraic program language that allows the user to enter lines of one or more alphanumeric algebraic statements into the calculator from the keyboard input unit while visually observing each line as it is entered to check for errors therein. The user may immediately execute each entered line or store that line as part of a program in the read-write memory, may subsequently recall the executed or stored line so that it may be reinspected, and, if necessary, edited and re-executed or re-stored, thereby automatically replacing the previously stored line. The program language of the calculator is contained within a plug-in language read-only memory and may be changed by inserting a different language read-only memory.

Programmable calculator

An adaptable programmable calculator employs modular read-write and read-only memories separately expandable to provide additional program and data storage functions within the calculator oriented toward the environment of the user, and an LSI NMOS central processing unit, capable of handling sixteen-bit parallel binary operations, binary-coded-decimal arithmetic, sixteen-bit parallel input/output operations, two-level interrupt from up to sixteen input/output devices, and a direct memory access channel. The input/output units include a keyboard input unit having a full complement of alphanumeric keys, a magnetic tape cassette reading and recording unit capable of bidirectionally transferring programs and data between the calculator and a magnetic tape, a 32-character solid state output display unit capable of displaying every alphabetic and numeric character and many other symbols individually or in combination, and a sixteen-column alphanumeric thermal printer for printing results of computations, program listings, messages generated by the user and the calculator itself, and error conditions encountered during use of the calculator. All of these input/output units are included within the calculator itself. Many other external input/output units may be employed with the calculator. The calculator may be operated manually by the user from the keyboard input unit or automatically through a program stored within the read-write memory to perform calculations and to provide an output indication of the results thereof. While a program stored within the read-write memory is being executed, the user can perform calculations manually from the keyboard. Execution of the program is temporarily suspended at convenient points within the program to allow execution of the calculations manually selected by the user. If desired, the user may be prevented from manually selecting calculations from the keyboard input unit by disabling the keyboard input unit during program execution. The calculator employs a natural algebraic program language that allows the user to enter lines of one or more alphanumeric algebraic statements into the calculator from the keyboard input unit while visually observing each line as it is entered to check for errors therein. The user may immediately execute each entered line or store that line as part of a program in the read-write memory, may subsequently recall the executed or stored line so that it may be reinspected, and, if necessary, edited and re-executed or re-stored, thereby automatically replacing the previously stored line. The program language of the calculator is contained within a plug-in language read-only memory and may be changed by inserting a different language read-only memory.

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Longmont, CO, United States of America

John H Nairn