The Museum of HP Calculators

# Hewlett-Packard advances in measurement and computation

"It's against reason," said Filby.
"What reason?" said the Time Traveller.
-H.G. Wells, The Time Machine (1895)

# The HP-01: a new kind of "time machine" you wear on your wrist

Hewlett-Packard advances in measurement and computation The HP-01: a new kind of "time machine" you wear on your wrist. New tools sometimes demonstrate their full significance only after people have invented a new range of uses for them. Their existence precedes their "reason" for existence. The HP-01 may be such a tool. It results from a timely fusion of two Hewlett-Packard technologies-precision time measurement1 and computation-and interrelates timekeeping with a computing element for the first time in a wrist-sized instrument.

Any resemblance between the HP-01 and a watch/calculator stops inside the case. What makes the HP-01 a new kind of "time machine" is that it can compute time data to produce numerical perspectives in time. For example:

It displays hours, minutes, and seconds in 12- or 24-hour formats. Adds and subtracts time intervals from present time, and lets you use time intervals or segments in arithmetic manipulations.

It times by increments of .01 seconds from 00:00.00 to 99:59:59. You can take cumulative splits (freeze an exact time in the display as the stopwatch continues to run) as often as desired. It starts backwards from any nonzero time up to 99:59:59, counts down to zero, sounds an alarm, and counts forward as described above. (A second, separate alarm can be set to sound anytime during a 24-hour day). You can make continuously updated arithmetical calculations using the stopwatch or timer.

It displays the current day, month, year (or month, day, year). Preprogrammed 200-year calendar allows the HP-01 to find the number of days between dates, or any date given any other date and number of days, or the day of the week or year.

It computes. Whether interactively or not, it adds, subtracts, multiplies, divides; performs chain, mixed chain, serial, and mixed serial calculations; finds percentages, changes signs. Computes to 11-digit accuracy and rounds the display to seven digits. Automatically switches to scientific notation when the answer is equal to or greater than 107 or less than 10-4, with a range of 1 x 10-99 to 9.999 x 1099. Lets you store data and recall it for further computation in memory. You can, for instance, keep a numeric quantity in continuous memory.

Admittedly not everyone's cup of tea, the HP-01 offers fascinating ways to compute and keep track of numbers in the time domain. For example, you can compute and then count down the time it takes for a command to reach a spacecraft several hundred million miles away. The HP-01 can alternately show you the time remaining until the message is received, displayed to seconds or hundredths of seconds, and the distance the radio waves have yet to travel, updated each second. When the message arrives (T zero) the HP-01's alarm sounds automatically.

Because only a relatively small number of these instruments will be made, we suggest you start your own discovery process by mailing the coupon now Call 800-648-4711 in the U.S.A. (in Nevada, call 323-2704 collect) for the name of the HP-01 retailer nearest you.

The HP-01 with accessories costs \$650* in stainless steel, or \$750* with gold-filled case and gold-plated band. With its 200-year calendar, it not only bridges the generation gap, but represents a legacy of sorts.

*Domestic USA prices only.

1HP cesium beam frequency and time standards keep time with an accuracy equivalent to a 1-second error in 4500 years. They are used for calibration at observatories and at national centers for measurement standards throughout the world. The HP-01 is calibrated against this standard, though obviously it does not possess the same degree of accuracy.