PCjs Machines

Texas Instruments TI-57 Patents

Thanks to research done in 2005 by Mike Sebastian, we know of 9 patents granted to Texas Instruments, all of which describe both the hardware and software of the TI-57 in surprising detail.

Of these 9 patents, the first 8 were filed on October 27, 1976, and the last was filed on March 23, 1979. The issue dates are in the same order as the patent numbers, with the first issue date being almost one and a half years later (March, 7, 1978).

• U.S. Pat. No. 4,078,251: ELECTRONIC CALCULATOR OR MICROPROCESSOR WITH MASK LOGIC EFFECTIVE DURING DATA EXCHANGE OPERATION
• U.S. Pat. No. 4,079,459: TWO SPEED SHIFT REGISTER FOR ELECTRONIC CALCULATOR OR MICROPROCESSOR SYSTEM
• U.S. Pat. No. 4,100,600: DATA DISPLAY SYSTEM FOR ELECTRONIC CALCULATOR OR MICROPROCESSOR
• U.S. Pat. No. 4,107,781: ELECTRONIC CALCULATOR OR MICROPROCESSOR WITH INDIRECT ADDRESSING
• U.S. Pat. No. 4,125,867: ELECTRONIC CALCULATOR OR MICROPROCESSOR HAVING A HEXADECIMAL/BINARY CODED DECIMAL ARITHMETIC UNIT
• U.S. Pat. No. 4,125,901: ELECTRONIC CALCULATOR OR MICROPROCESSOR HAVING A MULTI-INPUT ARITHMETIC UNIT
• U.S. Pat. No. 4,146,928: POWER UP CLEAR SYSTEM FOR AN ELECTRONIC CALCULATOR OR MICROPROCESSOR
• U.S. Pat. No. 4,164,037: ELECTRONIC CALCULATOR OR MICROPROCESSOR SYSTEM HAVING COMBINED DATA AND FLAG BIT STORAGE SYSTEM
• U.S. Pat. No. 4,277,675: NON-SEQUENTIAL COUNTER

I’ve compared a few of these patent texts to each other. Using 4,125,901 as an arbitrary baseline, I compared it to the first patent in the list (4,078,251), and aside from the introductory text and claims, the vast majority of the text and diagrams are identical, with most differences being either typist mistakes or OCR quirks.

I should add that the text for all of the patents above came from Google, although I apparently could have obtained the same full-text results from the U.S. Patent and Trademark Office as well, since all these patents were issued after 1976.

The back of every TI-57 also mentions these patents:

THIS PRODUCT AND ITS COMPONENTS ARE PROTECTED
BY ONE OR MORE OF THE FOLLOWING U.S. PATENTS
AND OTHER PATENTS PENDING:

       3819921    3955181
       3904863    3987416
       3921142    3988604
       3932846    3989939
       3934233    3991305
       3952174    3991306
       3855577    4014013
       4005293

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