Scientific Calculators: The Good Old Days Are Now
Pictured above is the HP-35, Hewlett-Packard's first pocket calculator and the world's first scientific pocket calculator. The HP-35 was available from 1972 to 1975, and retailed then for $395 (more than $2,000 it today's dollars).
Market studies at the time had shown no market for pocket sized calculators. However, HP co-founder Bill Hewlett began development of a "shirt-pocket sized calculator," and it turned out that the marketing studies were wrong. In the first months orders were exceeding HP's expectations as to the entire market size. 100,000 HP-35 calculators were sold in the first year, and more than 300,000 by the time it was discontinued in 1975, 3 and 1/2 years after its introduction.
The new HP 35s Scientific Calculator was introduced in 2007 to commemorate the 35th anniversary of the HP-35, and it sells today for about $50, or 1/40th the price of the original HP-35 in constant dollars.
HT: Lee Coppock
Update: The calculator used three rechargeable 'AA'-sized NiCd batteries assembled into a removable proprietary battery pack. Thanks to Tseeba for the information.