Merlin The Classic series


The Classic series was the first series of pocket calculators build by Hewlett Packard.
This series was build between 1972 and 1982 and contains 7 different models.

Model Code Type Qualification Classic
HP-35 none Scientific First HP pocket calculator
HP-45 Wizard Scientific Improved HP 35
HP-55 Merlin Scientific Like the HP 65 but without card reader,
less functions, but with a stopwatch function.
HP-65 Superstar Scientific Top model with magnetic card reader.
HP-67 Hawkeye Scientific Improved HP 65 with additional functions
HP-70 Scrooge Business Simplified HP 80
HP-80 none Business First HP pocket business calculator


The LED display

Display HP55 The picture on the left shows the LED display from the Classic series calculator. This display counts 15 digits. The division is fixed. The first digit is only used for the minus sign. The next 11 digits are used to display the mantissa and the decimal separator. This decimal separator occupies a complete digit. The 13th digit displays the sign of the exponent and the last two digits display the two digit exponent.


The keyboard

Keyboard HP55

As mentioned above, the HP- 35 borrows its model number from the number of keys on the keyboard. All other models from the Classic series also share the same keyboard layout with 35 keys.

The picture on the left shows clearly the wide ENTER key and the different colors used for of the keys. The yellow and blue keys are shift keys. These keys enable the yellow and blue printed functions above the other keys.


The battery package with rechargeable batteries


HP 82001A and HP 82001B

The calculators of the Classic series are supplied from a battery pack of 3 AA size Nicad cells. The batteries are connected in series to deliver a total supply voltage of about 3.6 Volt.

The batteries are charged when the calculator in supplied by the charger.

For more information about the HP battery packs can be found here.


The charger

Supply Supply plug Charger HP 82010A

Information that is written on the charger:

Primary voltage:
86 - 127V, 172 - 254V ac

Secundary voltage and current:
4.2V 50mA, 4V 150mA

More information about HP chargers can be found here.



Classic pouche   Pouche classic
Pouch for the Classic series fabricated from real leather. It is fasten with a strip of Velcro.   HP 82053A Pouch for the Classic series fabricated from imitation leather. This pouch has a zipper. The brand name Hewlett Packard and its logo are embossed in the pouch.
HP82007 Security cradle



Classic series related links:

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