This article is excerpted (with kind permission) from A Guide to HP Handheld Calculators and Computers, 2003 HHC 3rd edition, by Wlodek Mier-Jedrzejowicz, by Wilson/Barnett Publishing (Tustin, California, USA), ISBN 1-888840-30-7, $25.95 plus shipping ($5 US, $10 other countries). While the main focus is on Hewlett Packard pocket electronic calculators, it also has a section on the Hewlett Packard HP-01 LED calculator watch. The book is still in print and available by contacting The reference section of www.TheDigitalWatch.com"> Guy Ball.
The Hewlett Packard HP-01 combined wristwatch and calculator (click here for photo) was introduced on the first of July 1978. At least, that is the date on the display board at Corvallis - actually, it was announced in HP Key Notes and put on HP's Corporate Price List (CPL) in June 1977, described in detail in the HP Journal in December 1977, and I have one made early in 1977, so there must have been at least a semi-official introduction in June 1977.
The number 01 was kept for a very special product and indeed the HP-01 was very special and impressive. It came in two versions, with a brushed steel case, or a "gold-filled" case. Matching steel or gold-plated watchbands were provided, but leather bands were available too - at 160 grams with watchband these wristwatches were heavy and a leather watchband lightened the burden. They were large for a wristwatch too - the case was 1.8" by 1.6" by 0.5" (4.5 by 4 by 1.3 cm).
Unlike some combination watch/calculators, the HP-01 integrated the watch with the calculator so that the current time or date could be included in a calculation. The calculator was of the simple algebraic kind, with no extra features apart from the inclusion of date and time arithmetic - though that was very impressive.
The watch included a stopwatch and an audible alarm - one of the reasons for the codename being Cricket. It ran on three button batteries - one to drive the electronics and two to drive the display. The display was an LED one, which consumed significant power, so the watch would turn off its display very quickly after use - an annoying but necessary feature.
Most of the buttons were recessed so they could not be pressed by accident - only the Time, Date, Memory and Alarm buttons stood above the keyboard so they could be used easily. To help the user press the other buttons, a small stylus was included in the clasp of the watchband - you could pull it out to press the buttons, then put it back. A ballpoint pen also came with each HP-01; it had a retractable ball point at one end and a retractable plastic tip at the other end, so it could be used to push the buttons.
A third accessory was sold separately - a small round black plastic case with a transparent screw-on plastic top. A spare waterproof washer for the HP-01 case was placed between the two halves of this case - this could be used to replace the washer between the two halves of the case, to keep the case waterproof when the original washer became worn.
The case held up to five batteries, and the underside was shaped so it could be used as a tool to unscrew the HP-01 case to fit new batteries. All three accessories are shown with both HP-01 versions in the photograph in the middle of this guide. (web-guy's note: the guide mentioned is Wlodek's book which can be purchased at the website noted above.)
The steel version came with a keyboard which had white-on-grey buttons, with function keys in yellow, and the gold version had white-on-bronze buttons, with function keys in yellow on bronze. The watches were not waterproof but HP said they could be kept under water for a short time - so some users kept them on when washing - dishes! It was soon reported that the gold plate tended to come off early units if they came into contact with detergent - the problem was resolved as the repair was expensive!
HP decided to sell the HP-01 only through selected watch shops, not through their usual calculator dealers. Watch shops had mostly not heard of HP before, nor had many of their customers, and the HP-01 watches were expensive - $650 for the steel case version and $750 for the gold version. (These prices were raised to $695 and $850 on 1 July 1978.) This meant that sales were low. HP has not released sales statistics but in 1994 an HP employee posted a message on the Usenet area comp.sys.hp.misc about this. The message said that a total of about 50,000 HP-01s had been made, of which about a half had been purchased by a Saudi prince. Half the rest were sold through shops, then the remainder were sold to HP employees at a clearance price of $180 (the message did not specify if the steel and gold versions were both sold at the same price).
It is certainly true that the HP-01 is rare, but that a steady trickle continues to come onto the market as HP employees sell their HP-01s. The price for one in nearly new condition with the accessories is close to the new price, though used ones and ones without the two stylus accessories are worth significantly less. It is worth paying a lot to get the battery holder and case opener - apart from its value to complete a collection it does make replacing the batteries much easier. Prices of $40 for a steel pen, $60 for a gold pen, and $20 for the battery holder ($40 if it still has the washer) would not be unreasonable. Another reason for low sales was that the new LCD displays were just being introduced when the HP-01 came to the market. These are much less battery-consuming and can be kept active all the time. A whole family of HP-01 successors was considered, using the new display technology, but all that came of these plans were codenames such as "Firefly" (though this suggests an LED display!) and model numbers such as HP-02. A few HP-02 prototypes were made, and model numbers HP-02 to HP-07 were at one stage placed on the HP Corporate Price List, though the model numbered HP-02 on that list actually turns out to be the gold HP-01.
The HP-01 is not strictly speaking a handheld calculator, but it certainly has its place in many collections of HP handhelds. It is also considered a collectable in its own right, so if you find one on sale be prepared to bid against people who have no interest in HP calculators but who find this particular example of HP design highly desirable for its own sake!