What Happened on January 4th

the HP-35
the HP-35
 
Hewlett-Packard Introduces the HP-35
Hewlett-Packard introduces the HP-35, the first scientific handheld calculator and the final step in ending reliance on slide rules among scientists and students alike. The HP-35 was named for its 35 keys, weighed nine ounces, and sold for $395. One of the tests HP co-founder Dave Packard applied to the device was to throw it across his office and see if it still worked. It did.