Hewlett-Packard HP-65

Date of introduction:  January 19, 1974 Display technology:  LED
New price:  $795 (MSRP 1974) Display size:  10 + 2 
Size:  5.9" x 3.2" x 1.40"
 151 x 81 x 36 mm3
Weight:  10.9 ounces, 308 grams Serial No:  1333A23534
Batteries:  3*NiCd AA-size Date of manufacture:  wk 33 year 1973
AC-Adapter:  HP-82002 Origin of manufacture:  USA
Precision:  10 Integrated circuits:  HP65-CPU, Mostek MK6111...MK6113
Memories:  9    
Program steps:  100 Courtesy of:  Ken H. Meine

Hewlett-Packard introduced on January 19, 1974 with the HP-65 the World's first Pocket Programmable Calculator. A marvel of engineering at its time, the HP-65 accommodates in a housing only slightly larger than the legendary HP-35 a card reader for its tiny magnetic strips to archive programs. Users could store programs with up to 100 steps on the cards or buy pre-programmed cards from either Hewlett Packard or third party companies.

The HP-65 was replaced after 2 years with the HP-67 featuring 224 merged program steps and 26 memories instead of 100 partially merged program steps and 9 memories. Compare these specifications with both the Texas Instruments SR-56 and SR-52 programmable calculators.

The HP-65 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-65 with Date code 1333A manufactured in August 1973  by Hewlett Packard in the United States reveals a very solid design centered around a Hewlett Packard proprietary CPU (Central Processing Unit) with multiple Integrated Circuits (ICs) mounted in a ceramic package and supported by three MK611X ROMs (Read-only Memories) with a capacity of 1,024*10 Bits, each and manufactured by US semiconductor company Mostek. Please notice the Date codes on these chips, they were manufactured between week 10 and week 32 in the year 1974 - an obvious sign for some update of the microprogramming of the HP-65.

Learn more about Mostek Calculator Integrated Circuits.


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