1. Computer History

2. First Computer
ABACUS

3. Blaise Pascal

4. Gottfried Wilhelm von Leibniz
Stepped Reckoner
Gottfried Wilhelm von Leibniz

5. Joseph Jacquard

7. Charles Babbage
Charles Babbage

8. Babbage's Difference Engine
Charles Babbage
Babbage's Difference Engine

9. Analytical Engine

10. First Computer Programmer
Ada Byron, Countess of Lovelace

11. Herman Hollerith

12. Tabulating Machine

13. Hollerith’s Punch Card

14. Tabulating Machine Company
International Business Machines

15. Mark I Calculator
One early success was the Harvard Mark I computer which was built as a partnership between Harvard and IBM in This was the first programmable digital computer made in the U.S. But it was not a purely electronic computer. Instead the Mark I was constructed out of switches, relays, rotating shafts, and clutches. The machine weighed 5 tons, incorporated 500 miles of wire, was 8 feet tall and 51 feet long, and had a 50 ft rotating shaft running its length, turned by a 5 horsepower electric motor. The Mark I ran non-stop for 15 years, sounding like a roomful of ladies knitting. To appreciate the scale of this machine note the four typewriters in the foreground of the following photo.

16. Howard Aiken
Mark I

17. ENIAC

18. Vacuum Tubes

19. Vacuum Tubes

20. Transistor

21. Transistor Radio

22. First Computer Bug