woodstock The Woodstock series


The Woodstock series were build between 1975 and 1979. This series contains 6 different models which are an inexpensive alternative for the calculators of the Classic series.

Two interesting articles about the development of the first models of this Woodstock series can be found in the HP Journal of November 1975. These articles can also be downloaded here:

Woodstock is the small yellow bird from the famous Peanuts (Charlie Brown, Snoopy) comic.

HP-21 Pumpkin Scientific
Basic calculator, not programmable
HP-22 Turnip Business
Basic calculator, not programmable
HP-25 Squash Scientific
Basic calculator, programmable
HP-25C Squish Scientific
As the HP-25 with continuous memory
HP-27 Salad Scientific
Basic calculator, not programmable
HP-29C Bonnie Scientific
Improved HP-25C with continuous memory


The display

display woodstock

To build a smaller calculator, the number of digits in the LED display was reduced from 15 (used for the Classic series) to 12. The first digit is only used to display the minus sign, the next 11 digits are used to display the result. The decimal separator is now part of the digit and no longer occupies a complete digit, like the Classic series.


The keyboard

Keyboard Woodstock

The keyboard of the calculators of the Woodstock series counts only 30 keys. To activate all the functions these calculators have one or two colored prefix keys. The picture on the left shows the keyboard of the HP-25. This calculator has 2 prefix keys, labeled f and g.


HP 82019A/B The battery pack with rechargeable batteries.

Woodstock battery pack

The calculators from the Woodstock series are supplied by two AA type NiCd cells. These cells are connected in series, which results in a total voltage of 2.4 Volt.

The batteries are charged in the calculator by the main charger. The charger electronics is build in the calculator and not in the main adapter as it was done for the Classic series.

More information about these batteries can be found on my battery page.



HP 82024A

Main charger. Secondary 10 VAC 1.8VA. This charger contains a single transformer. Other chargers for the woodstock series can be found on my chargers page.

Adapter HP82024A plug


HP 82028A Reserve Battery Pack

Small external charge adapter for the woodstock battery pack. For more information see here.



Imitation leader pouch with a large zipper.

Pouche Woodtock line

Woodstock related links:

For more Woodstock series related links see the specific Woodstock model pages.