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The HP-65 is the first magnetic card-programmable handheld calculator. Introduced by
Hewlett-Packard The Hewlett-Packard Company, commonly shortened to Hewlett-Packard ( ) or HP, was an American multinational information technology company headquartered in Palo Alto, California. HP developed and provided a wide variety of hardware components ...
in 1974 at an
MSRP The list price, also known as the manufacturer's suggested retail price (MSRP), or the recommended retail price (RRP), or the suggested retail price (SRP) of a product is the price at which its manufacturer notionally recommends that a retailer ...
of $795 (), it featured nine storage registers and room for 100 keystroke instructions. It also included a magnetic card reader/writer to save and load programs. Like all Hewlett-Packard calculators of the era and most since, the HP-65 used
Reverse Polish Notation Reverse Polish notation (RPN), also known as reverse Łukasiewicz notation, Polish postfix notation or simply postfix notation, is a mathematical notation in which operators ''follow'' their operands, in contrast to Polish notation (PN), in wh ...
(RPN) and a four-level automatic operand
stack Stack may refer to: Places * Stack Island, an island game reserve in Bass Strait, south-eastern Australia, in Tasmania’s Hunter Island Group * Blue Stack Mountains, in Co. Donegal, Ireland People * Stack (surname) (including a list of people ...
.
Bill Hewlett William Redington Hewlett ( ; May 20, 1913 – January 12, 2001) was an American engineer and the co-founder, with David Packard, of the Hewlett-Packard Company (HP). Early life and education Hewlett was born in Ann Arbor, Michigan, where his ...
's design requirement was that the calculator should fit in his shirt pocket. That is one reason for the tapered depth of the calculator. The magnetic program cards are fed in at the thick end of the calculator under the LED display. The documentation for the programs in the calculator is very complete, including algorithms for hundreds of applications, including the solutions of differential equations, stock price estimation, statistics, and so forth.


Features

The HP-65 introduced the "tall", trapezoid-shaped keys that would become iconic for many generations of HP calculators. Each of the keys had up to four functions. In addition to the "normal function" printed on the key's face, a "gold" function printed on the case above the key and a "blue" function printed on the slanted front surface of the key were accessed by pushing the gold or blue prefix key, respectively. For example, followed by would access the sine function, or followed by would calculate 1/x. For some mathematical functions, a gold prefix key would access the inverse of the gold-printed functions, e.g. followed by would calculate the inverse sine (\sin^). Functions included square root, inverse, trigonometric (sine, cosine, tangent and their inverses), exponentiation, logarithms and factorial. The HP-65 was one of the first calculators to include a base conversion function, although it only supported octal (base 8) conversion. It could also perform conversions between degrees/minutes/seconds (
sexagesimal Sexagesimal, also known as base 60 or sexagenary, is a numeral system with sixty as its base. It originated with the ancient Sumerians in the 3rd millennium BC, was passed down to the ancient Babylonians, and is still used—in a modified form ...
) and decimal degree (
sexadecimal In mathematics and computing, the hexadecimal (also base-16 or simply hex) numeral system is a positional numeral system that represents numbers using a radix (base) of 16. Unlike the decimal system representing numbers using 10 symbols, hex ...
) values, as well as polar/cartesian coordinate conversion.


Programming

The HP-65 had a program memory for up to 100 instructions of 6 bits which included subroutine calls and conditional branching based on comparison of x and y registers. Some (but not all) commands entered as multiple keystrokes were stored in a single program memory cell. When displaying a program, the key codes were shown without line numbers. A program could be saved to mylar-based magnetically coated cards measuring , which were fed through the reader by a small electric motor through a worm gear and rubber roller at a speed of . The recording area used only half of the width of the card. While reversing the card to store a second program was possible, it was officially discouraged (unlike in later models such as the
HP-67 The HP-67 is a magnetic card-programmable handheld calculator, introduced by Hewlett-Packard in 1976 at an MSRP of $450. A desktop version with built-in thermal printer was sold as the HP-97 at a price of $750. Marketed as improved successo ...
) because the other half of the card was touched by the rubber wheel during transport, causing extra abrasion. When inserted into an extra slot between the display and the keyboard, the printing on top of the card would correspond to the top row of keys (A - E), which served as shortcuts to the corresponding program entry points. Cards could be write-protected by diagonally clipping the top-left corner of the card. HP also sold a number of program collections for scientific and engineering applications on sets of prerecorded (and write-protected) cards. The HP-65 had an issue/design flaw whereby storage register R9 was corrupted whenever the user (or program) executed trigonometric functions or performed comparison tests; this kind of issue was common in many early calculators, caused by a lack of memory due to cost, power, or size considerations. Since the limitation was intended from the beginning and documented in the manual, it is not, strictly speaking, a bug.


Significant applications

During the 1975 Apollo-Soyuz Test Project, the HP-65 became the first programmable handheld calculator in
outer space Outer space, commonly shortened to space, is the expanse that exists beyond Earth and its atmosphere and between celestial bodies. Outer space is not completely empty—it is a near-perfect vacuum containing a low density of particles, pred ...
. Two HP-65s were carried on board the Apollo spacecraft. Calculation of parameters for the several thrusting maneuvers needed to rendezvous with the Soyuz spacecraft was done on the HP-65 and compared with the results calculated by the onboard
Apollo Guidance Computer The Apollo Guidance Computer (AGC) was a digital computer produced for the Apollo program that was installed on board each Apollo command module (CM) and Apollo Lunar Module (LM). The AGC provided computation and electronic interfaces for guidanc ...
. Another program for the HP-65 allowed the crew to compute pointing angles for the spacecraft antenna for aiming at the ATS-6 communications relay satellite. In the same year, Mitchell Feigenbaum, using the small HP-65 calculator he had been issued at the
Los Alamos National Laboratory Los Alamos National Laboratory (often shortened as Los Alamos and LANL) is one of the sixteen research and development laboratories of the United States Department of Energy (DOE), located a short distance northwest of Santa Fe, New Mexico, ...
, discovered that the ratio of the difference between the values at which successive period-doubling bifurcations occur tends to a constant of around 4.6692... This "ratio of convergence" is now known as the first Feigenbaum constant.


See also

* HP-25 * HP-35 * 65 Notes


References


External links


The HP-65
at an unofficial Hewlett-Packard museum
MyCalcDB
; includes a photograph of the magnetic card.
1975 HP Calculator Christmas Guide




page at the unofficial Museum of HP Calculators * One of the HP-65s carried on the ASTP space flight is in th
collection
of the
National Air and Space Museum The National Air and Space Museum of the Smithsonian Institution, also called the Air and Space Museum, is a museum in Washington, D.C., in the United States. Established in 1946 as the National Air Museum, it opened its main building on the N ...
. {{HP calculators 65 Computer-related introductions in 1974