United States Patent 4,009,379
Portable Programmable Calculator Displaying Absolute Line Number Addresses and Key Codes and Automatically Altering Display Formats
Feb. 22, 1977
Inventor: Bernard E. Musch, Palo Alto, Calif.
Assignee: Hewlett-Packard Company, Palo Alto, Calif.
Filed: Dec. 16, 1974
Appl. No.: 533,430
Abstract:
A battery-powered hand-held programmable calculator for performing arithmetic,
trigonometric and logarithmic functions and displaying the results thereof is
provided with the capability of being fully programmable including branching
based on data value. Absolute line number addressing is provided. Program
line numbers and the key code associated with an executable step are displayed.
The top of the programmable memory is configured as a nonexecutable line
corresponding to an automatic stop and all other programmable lines are
initially programmed upon start up as being an automatic branch to the top of
the memory. key codes representing a plurality of actuated keys corresponding
to a branch instruction are merged to require only one program line in memory.
21 Claims, 7 Drawing Figures
An image of first page of this patent is
available (approximately 48 Kbytes).
It is a TIFF class F file at 300 DPI resolution using ITU-T Group 4 Facsimile
(T.6) coding.
Eric's notes:
This patent describes the HP-55. It contains the entire microcode ROM
listing of the HP-55, although the copies I have obtained from microfilm and
CD-ROM are illegible in many spots and are stamped "BEST COPY AVAILABLE".
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Last updated July 17, 1995
Copyright 1995 Eric Smith
eric@brouhaha.com
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