The Curta hand cranked calculator was introduced in 1948. Developed by Curt Herzstark, it can do basic arithmetic and, a bit laboriously, square roots. This pepper grinder-like black cylinder is mechanically complex, beautifully made and ingenious.
Even though it remained popular in specific areas, such as sports car rallies even into the 1980s, it was generally superseded by the classic slide-rule in the 1950s and 60s. But who knows? Perhaps in the back of Jony Ive's mind, there loomed the concept of a black computational cylinder that ultimately resulted in the design of the late 2013 Mac Pro.
Computational speed: Looks like a blazing hertz or two.