Hewlett-Packard HP-35 Handheld Electronic Calculator

The HP-35 was the first handheld electronic calculator to compute all the functions represented on a slide rule. It has a black plastic case and a total of thirty-five square or rectangular plastic keys. These include ten digit keys, a decimal point key, and a pi key, all colored tan. In addition there are four arithmetic function left of the digit keys, a relatively long enter key, a change sign key, and enter exponent key, a clear x key, and a clear key, all in blue. Additional black keys are for powers, logs to base ten, natural logs, exponents, square roots, trigonometric functions (sine, cosine, tangent and the inverses of these), simple inverses, exchange, roll down, store, and recall. Above the keys is an on/off switch. There is no hole next to the switch to indicate that the display is on, as there was in the very first HP-35 calculators. Behind the switch is a red LED display that shows results. Numbers with absolute value between one hundredth and 10 billion are given in decimal form. Smaller or larger ones appear in scientific notation, with the appropriate power of ten occupying the three rightmost digit places (two for digits, one for a sign). The negative sign for the result, if needed, is at the far left. A mark on the front edge of the calculator reads: hp HEWLETT•PACKARD.

The back of the calculator has a plug for a three-prong power adapter, a compartment for a battery pack, four rubber feet, and a sticker entitled: HEWLETT•PACKARD MODEL 35 INSTRUCTIONS. Text below the sticker reads: HEWLETT-PACKARD (/) 3.75V 500MW (/) MADE IN USA PATENT PENDING. A sticker inside the battery pack reads: HEWLETT-PACKARD (/) SER.NO. 1302A 27645. The portion 1302 of the serial number suggests that it was made in the second week of 1973. A red sticker on the lid of the battery pack reads: CAUTION (/) USE ONLY H. P. BATTERY PACK (/) MODEL NO 82001A (/) OTHER BATTERIES MAY DAMAGE CIRCUITS.

In addition to the calculator, the gray plastic case contains a power adapter labeled in part HEWLETT - PACKARD (/) MODEL 82002A. It also has a carrying pouch, battery packs, and a battery case.

According to the donor, Nicholas Grossman, he ordered the calculator when it was first announced and received it, paying $395 plus shipping, six weeks later. The HP-35 was first announced in early 1972.

Received with the calculator were two documents, the HP-35 Operating Manual and HP-35 Math Pac.

References:

W.A.C. Mier-Jedrzejowicz, A Guide to HP Handheld Calculators and Computers , Tustin, California: Wilson/Burnett Publishing, 1997, pp. 36–39, 132.

David G. Hicks, The Museum of HP Calculators, http://www.hpmuseum.org/, accessed July 2014.

Thomas M. Whitney, France Rodé, and Chung C. Tung, “The ‘Powerful Pocketful’: an Electronic Calculator Challenges the Slide Rule,” Hewlett-Packard Journal, June 1972, pp. 2–9.

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