Hewlett Packard HP 65 Calculator, serial 1333A 06752
The date code on this HP-65 (1333) is the earliest know for this model1 indicating it was manufactured in week 33 of 1973 (1960+13). The HP-65 was not actually released for sale until January 1974.
The HP-65 represented a further leap forward by coupling a magnetic card reader with the calculator. Now it could be programmed and programs could be stored for future use. With this step it became a tiny pocket computer and some fantastic uses were found for the capabilities it had thus acquired. Algorithms were developed for hundreds of applications, including the solution of differential equations, estimation of stock prices, statistical analyses, and many more complicated programs. With specially prepared programs, an HP-65 acted as a backup computer in the Apollo space mission in its rendezvous with a Russian Soyuz space craft on 17 July 1975.
The following advertisement in September 1975 in Scientific American captures that moment:
“HP-65 in space with Apollo-Soyuz.
The American astronauts calculated critical course-correction maneuvers on their HP-65 programmable hand-held during the rendezvous of the U.S. and Russian spacecraft.
Twenty-four minutes before the rendezvous in space, when the Apollo and Soyuz were 12 miles apart, the American astronauts corrected their course to place their spacecraft into the same orbit as the Russian craft. Twelve minutes later, they made a second positioning maneuver just prior to braking, and coasted in to linkup.
In both cases, the Apollo astronauts made the course-correction calculations on their HP-65. Had the on-board computer failed, the spacecraft not being in communication with ground stations at the time, the HP-65 would have been the only way to make all the critical calculations. Using complex programs of nearly 1000 steps written by NASA scientists and pre-recorded on magnetic program cards, the astronauts made the calculations automatically, quickly, and with ten-digit accuracy.
The HP-65 also served as a backup for Apollo’s on-board computer for two earlier maneuvers. Its answers provided a confidence-boosting double-check on the coelliptic (85 mile) maneuver, and the terminal phase initiation (22 mile) maneuver, which placed Apollo on an intercept trajectory with the Russian craft.
Periodically throughout their joint mission, the Apollo astronauts also used the HP-65 to calculate how to point a high-gain antenna precisely at an orbiting satellite to assure the best possible ground communications.
The first fully programmable hand-held calculator, the HP-65 automatically steps through lengthy or repetitive calculations. This advanced instrument relieves the user of the need to remember and execute the correct sequence of keystrokes, using programs recorded 100 steps at a time on tiny magnetic cards. Each program consists of any combination of the calculator’s 51 key-stroke functions with branching, logical comparison, and conditional skip instructions.”
1 see date list at the website of The Museum of HP Calculators (http://www.hpmuseum.org/collect.htm#numbers, viewed 19 July 2014 ) (↑)
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