The document summarizes the history of early mechanical and electromechanical computing devices: 1) The Pascaline, invented in 1642 by Blaise Pascal, was one of the first mechanical calculators capable of addition but had manufacturing problems. 2) Gottfried Leibniz's Stepped Reckoner of the 1670s could perform addition, subtraction, multiplication, division, and square roots. 3) Charles Babbage began designing the Difference Engine in 1822 to automate number tables but it was never completed, leading him to conceive the analytical engine. 4) The analytical engine, designed in 1833, was intended to perform calculations according to a set of stored instructions

1. Computer History

2. Mechanical Devices
Pascaline - 1642
 Invented by Blaise Pascal in 1642
 It was a complicated set of gears that operated similar to a
clock.
 Designed to only perform addition
 Manufacturing problems caused it not to work properly

3. Stepped Reckoner
• Invented by Gottfried Wilhelm von Leibniz
in the 1670’s
•Created to add, subtract, multiply, divide,
and calculate square roots

4. Difference Engine
computerhistory.org
• In 1822, Charles Babbage began working
on the Difference Engine
•Purpose was to create tables of numbers
used by ship’s navigators.
•It was never built but led to Babbage’s
Analytical Engine.

5. Analytical Engine
• Designed around 1833 by Charles
Babbage
• Purpose was to perform calculations by
following a set of instructions or program
• Information was to be stored in memory
•Ada Byron was Babbage’s chief
collaborator on the analytical engine. She
wrote a program based on the engine, thus,
becoming the first computer programmer.

6. Electro-Mechanical Devices
Tabulating Machine - 1890
 Invented by Herman Hollerith
 Invented for the 1890 Census
 Used electricity and not mechanical gears
 Used hole punch cards to tell the machine how to perform
the calculations needed

7. Mark I
• 1944 – IBM and Harvard University
created the Mark I.
•Howard Aiken was the team leader
•Used mechanical telephone relay switches
to store information and accepted data on
punched cards.

8. Assignment – Use the Internet to find 5
more facts about the following people
and inventions.
1. Pascaline
1. Blaise Pascal
2.Stepped Reckoner
2.Gottfried Leibniz
3.Difference Machine
3.Charles Babbage
4.Analytical Engine
4.Ada Byron
5.Tabulating Machine
5.Herman Hollerith
6.Mark I
6.Howard Aiken