Hewlett-Packard HP-25 Handheld Electronic Calculator

This handheld electronic calculator, relatively small and simple for a calculator sold by Hewlett-Packard, was introduced on February 1, 1975 and sold through 1978. It was one a series of calculators of this size that also included the HP-21, HP-22, HP-25C, HP-27, and HP-29C. The calculator has a tan plastic case with a black or dark brown keyboard and thirty rectangular plastic keys. Many keys take on different meanings if the gold "f" shift key or the blue "g" shift key is pressed. The calculator has limited programming capabilities but no device for storing instructions from one session to the next. Behind the keyboard are an on/off switch, a program/run switch, and a twelve-digit LED display (either ten digits plus sign, or eight significant digits plus two digits of an exponent plus signs for both). A mark on the front edge reads: hp HEWLETT • PACKARD 25.

The reverse side of the calculator has prongs for a power adapter/recharger as well as a battery compartment with a frame for two batteries. Stamped above the battery pack is the number: 1511A25777. The first four numbers of the serial number indicate that the calculator was made in the eleventh week of 1975. A tag at the base of the back reads: HEWLETT-PACKARD (/) MADE IN USA(/) 2.5 V 500mW.

The calculator is in a black plastic zippered carrying case marked: ti. It does not fit well.

In November, 1975, the calculator sold for $195.

References:

W.A.C. Mier-Jedrzejowicz, A Guide to HP Handheld Calculators and Computers , Tustin, California: Wilson/Burnett Publishing, 1997, pp. 46–48, 132.

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

Randall Neff and Lynn Tillman, “Three New Pocket Calculators: Smaller, Less Costly, More Powerful,” Hewlett-Packard Journal, November 1975, pp. 2-7, 12. Much of the issue is devoted to the HP-21, HP-22 and HP-25.

[Advertisement], Electronics, vol. 48 #23, November 13, 1975, pp. 92-93.

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