**Hewlett Packard HP-35**

**Hewlett Packard HP-35**

**Distinctive features:** The first hand-held scientific calculator.

**Technical details:**Display is scientific, 10 digits mantissa and 2 digits exponent, red LED.

Scientific, using Reverse Polish Notation (RPN) - as evidenced by the lack of an "=" key.

Main integrated circuits in this example - Mostek MK6020, MK6021, MK6022, MK6023, MK6024, which comprise three ROMs, a control and timing chip, and a register and arithmetic chip. This chip set was also second-sourced by AMI.

3.75v (3 x AA re-chargeable).

79 mm x 147 mm x 34 mm (3.1" x 5.8" x 1.4").

Introduced February 1972, cost $395 (about £165 GBP).

Made in U.S.A. & Singapore.

With the casing taken apart the circuit board with the integrated circuits is revealed.

On April 14th 2009 Hewlett Packard awarded the IEEE Milestone in Electrical Engineering and Computing for the HP-35 calculator, the first hand-held scientific calculator.

*"Introduced in 1972, the HP-35 was the world's first handheld-sized scientific calculator. An instant hit, the HP-35 ultimately made the slide rule, which had previously been used by generations of engineers and scientists,
obsolete.*

*The HP-35, named for its 35 keys, was the first handheld calculator to perform transcendental functions such as trigonometric, logarithmic and exponential functions.*

*In the first three years after its introduction in 1972, sales of the HP-35 Scientific Calculator exceeded 300,000 units."*

The article "The HP-35 Calculator: The first Electronic Slide Rule", in the Collecting Calculators section of this site, has further information about the HP-35.

There is a very interesting article "Made in the USA ... finally" about the development of the HP-35 on Rick Furr's calculator site, available in the archive at https://web.archive.org/web/20040203113550/http://www.vcalc.net/hp-35.htm.

There is a lengthy video on Youtube with an interview with Dave Cochran who was involved in the development of the HP-35 at https://www.youtube.com/watch?v=0IlSjfgrHVM.

If you would like to try out the "Reverse Polish Notation" operation of a very realistic virtual HP-35 visit Neil Fraser's site at http://vv.carleton.ca/~neil/hp-35/ and download his excellent Javascript simulation.

*This was the first hand-held scientific calculator. Hewlett Packard calculators were very well made, and reliable, and their
electronics instruments had (still have) a very good reputation. Together with the high specification, this made their calculators the models of choice for many professionals. 300,000 HP-35 calculators were sold ("New Scientist",
Feb. 1975).*

*While nearly all of the other calculator manufacturers concentrated on reducing the cost of their calculators, Hewlett Packard kept the cost high and increased the functionality. They introduced
the HP-65, the first hand-held programmable calculator, in 1974, and they are one of the few companies to continue making calculators from the early 1970s to the present day.*

**Hewlett Packard awarded the "IEEE Milestone in Electrical Engineering and Computing" for the HP-35 calculator
**

On April 14th 2009 Hewlett Packard announced that it had been awarded the prestigious "IEEE Milestone in Electrical Engineering and Computing" for the HP-35 calculator, the first hand-held scientific calculator.

Left to right presenting the IEEE HP-35 Milestone Award are: Lewis Terman (IEEE), Dave Cochran (HP-35), Richard Gowen (IEEE).

The press release explains:

*"Introduced in 1972, the HP-35 was the world's first handheld-sized scientific calculator. An instant hit, the HP-35 ultimately made the slide rule, which had previously been used by generations of engineers and scientists,
obsolete.*

*The HP-35, named for its 35 keys, was the first handheld calculator to perform transcendental functions such as trigonometric, logarithmic and exponential functions.*

*In the first three years after its introduction in 1972, sales of the HP-35 Scientific Calculator exceeded 300,000 units.*

*An IEEE Milestone plaque recording the award will be permanently displayed at HP Labs in Palo Alto, Calif., the site where the HP-35 was originally developed."*

A video of the presentation with some of those involved in the development of the HP-35 is viewable at http://www.ustream.tv/recorded/1383158.

**July 2007: Hewlett Packard launches Retro HP 35s to Commemorate 35th Anniversary of First HP Handheld Calculator.** More information on the Vintage Calculator News page.

Photograph of HP35s used with permission of HP.

**Hand-held Calculators**

*Vintage Calculators *

© Text & photographs copyright Nigel Tout 2000-2017 except where noted otherwise.