1. Lesson 3

2. 3‐1 The History of Computers
3‐2 The Earliest Computing Devices
1. Abacus
2. Napier’s Bones
3. Oughtred’s slide rule
4. Pascal’s Calculator
5. Leibnir’s Calculator
6. Babbage’s analytical Engine
7. Hollerith’s Punched‐card Machine

3.  Historical records will tell us that man has
invented three types of devices to assist him
in calculating and processing data. They are:
 Manual mechanical
 Eletromechanical
 Electronic

4.  Manual‐mechanical : A simple mechanism
powered by hand
 Abacus
 Slide rule
 Electromechanical: It is usually powered by an
electric motor and uses switches and relays.
 Household electrical appliances
 Calculators
 Punched cards

5.  Electronic : a device which has its principal
components circuit boards, transistors or
silicon chips and the like
 Modern digital computer

6. 3‐2 The Earliest
Computing Devices
1. Abacus

7. 3‐2 The Earliest
Computing Devices
2. Napier’s
Bones

8. 3‐2 The Earliest
Computing Devices
3.
Oughtred’s
Slide Rule

9. 3‐2 The Earliest
Computing Devices
4. Pascal’s
Calculator

10. 3‐2 The Earliest
Computing Devices
5. Leibniz’s
Calculator

11. 3‐2 The Earliest
Computing
Devices
6.
Babbage’s
Analytical
Calculator

12. 3‐2 The Earliest
Computing
Devices
7.Hollerith’s
Punched‐
card
Machine