Hewlett-Packard HP-35

Date of introduction:  July 1, 1972 Display technology:  LED
New price:  $395 (MSRP 1972) Display size:  10 + 2 
Size:  5.9" x 3.1" x 1.5"    
Weight:  6.0 ounces Serial No:  1302S23975
Batteries:  4*NiCd Date of manufacture:  wk 02 year 1973
AC-Adapter:   Origin of manufacture:  Singapore
Precision:  10 Integrated circuits:  
Memories:  1    
Program steps:   Courtesy of:  Peter Muckermann

Hewlett-Packard introduced in July 1972 the World's first pocket sized electronic calculator performing both logarithmic and trigonometric functions. The retail price of $395 was high but in a good balance with the $100 to $150 asking price mid of 1972 for the typical four-bangers (add, subtract, multiply and divide) like the Bowmar 901B or TI-2500 Datamath. It took some time before Texas Instruments introduced their first electronic Slide Rule named SR-50 with similar performance but a selling price of only $169.95. Don't miss the Corvus 500 calculator introduced in 1974.

The HP-35 uses the Reverse Polish Notation with the [ENTER] key instead the usual [=] key and takes the responsibility for:

The Death of the Slide Rule
The never ending Rivalry between TI and HP calculators users
The cat and mouse game leading to products like the HP-67 or TI-59

Dismantling the featured HP-35 manufactured in January 1973 by Hewlett Packard in its Singapore factory reveals a very solid design centered around an Arithmetic Chip, Control and Timing Chip, and three ROMs (Read-only Memories) from US semiconductor companies Mostek and AMI.

Learn more about Mostek Calculator Integrated Circuits.


Milestones of HP calculators

HP introduces in the year 1968 the World's first desktop scientific calculator, the HP 9100A. The programmable calculator stores programs on magnetic cards and lets scientists perform complex calculations without the need to access much larger computers. It is 10 times faster than most machines at solving science and engineering problems. Ads for the 9100A call the device a "personal computer," one of the first documented uses of the term.

Only 4 years later, on July 1st, 1972, HP makes another advance in personal computing with the HP-35, the World's first scientific handheld calculator. Small enough to fit into a shirt pocket, the powerful HP-35 makes the engineer's slide rule obsolete. With the HP-80 a similar business model was introduced in February 1st, 1973. In May of 1973 the HP-45 followed before the first programmable model HP-65 was introduced in January 19th, 1974 with a retail price of $795. It took another year to the introduction of the HP-55. Early in the year 1975 the price tag of the HP-35 dropped to $195 and the calculator was discontinued soon after.

In the year 1975 dozens of companies manufactured calculators with 4 functions and a selling price below $20, scientific and business calculators in the range around $100 and programmable calculators priced about $250. The slide rule was outdated and famous companies like Dennert & Pape (ARISTO), A.W. Faber-Castell and Keuffel & Esser stopped the production.

horizontal rule

If you have additions to the above article please email:

Joerg Woerner, May 3, 2002. No reprints without written permission.