United States Patent 3,859,635
Programmable Calculator

Issued: Jan. 7, 1975
Inventor: Robert E. Watson, Jack M. Walden, Charles W. Near
Assignee: Hewlett-Packard Company, Palo Alto, Calif.
Appl. No.: 153,437
Filed: June 15, 1971

Abstract:

A modular read-write and read-only memory unit capable of employing both direct and indirect decimal and symbolic addressing, a central processor unit capable of performing both serial binary and parallel binary-coded-decimal direct andindirect memory register arithmetic, and an input-output control unit capable of bidirectionally transferring information between the central processing unit and a number of input and output units are controlled by a microprocessor in the central processing unit. The input and output units include a keyboard input unit with a section 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, and a solid state output display unit capable of displaying three lines of numeric information. An output printer unit capabile of printing out every alphabetic and numeric character and many other symbols individually and in messages may also be included with the other input and output units.

The memory, central processing, input-output control, input, and output units are employed to provide an adaptable programmable calculator that may be operated manually by the user from the keyboard input unit or automatically by a p;rogram stored in the memory unit. This calculator may also be employed to load programs into the memory unit from the keyboard input unit, to separately transfer eithe redata or programs bidirectionally between the memory unit and an external magnetic card, to code programs stored int he memory unit as being secure when they are transferred to an external magnetic card and thereby prevent users of the calculator from re-transferring them to an external magnetic card or optaining any indication of the original program steps once they are reloaded into the calculator, to edit programs stored in the memory unit and to print out keystroke logs, program lists, labels, and messages. The read-write memory available to the user may be expanded by the addition of program storage memory modules or by the alteration of the data storage memory control.

17 Claims, 361 Drawing Figures

PDF file of US Patent 3,859,635 (412 pages, 17M)

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Last updated May 31, 2003

Copyright 2003 Eric Smith

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