History of Computing – SS1 Data Processing Lesson Note (First Term)

The history of computing traces how people developed devices for fast and accurate calculation, which led to the modern computer.

Behavioural objectives

By the end of the lesson, students should be able to:

1. list the early manual, mechanical, electro-mechanical and electronic calculating devices;
2. describe the abacus and state what it was used for;
3. state who invented Napier’s bones and the Pascaline, and what each did;
4. explain how Jacquard’s loom and the punched card used holes to store information;
5. name the four number systems used to represent data.

Why were calculating devices developed?

Calculating devices were developed because people needed to calculate faster and with fewer mistakes than working by hand.

• Speed: counting and sums done by hand take a long time.
• Accuracy: people make errors when they work with large numbers.
• Growing needs: trade, record keeping and science all required more calculation.
• Result: the search for fast and accurate devices led to the development of the computer.

What are the early counting and calculating devices?

Early calculating devices fall into four groups: manual, mechanical, electro-mechanical and electronic.

How did each early device work?

What is an abacus?

The abacus is a frame with beads that is used to count and to add and subtract.

• Origin: it is among the first calculating devices, and the Chinese form is the best known.
• Frame: a frame holds all the other parts.
• Horizontal bar: it divides the frame into two parts.
• Vertical threads: each thread carries some beads.
• Use: simple addition and subtraction.
• Today: it is still used in some countries because it is simple to operate.

What is a slide rule?

A slide rule is a ruler with sliding scales that is used to multiply and divide.

• Design: a fixed part and a sliding part, both marked with scales.
• Use: the user slides one scale against the other and reads the answer.

What were Napier’s bones?

Napier’s bones were a set of numbered rods invented by John Napier, a Scottish mathematician, for multiplication.

• Name: the rods were made from bones, so they were called Napier’s bones.
• Marking: numbers were marked on the rods in a special way.
• Method: the rods were placed side by side to give products and quotients of large numbers.

What was the Pascaline?

The Pascaline was the first mechanical calculating machine, invented in 1642 by Blaise Pascal, a French mathematician.

1. The user entered numbers by dialling a series of numbered wheels.
2. A sequence of wheels passed the movement on to a dial.
3. The dial showed the result.

• Addition and subtraction: the machine did both directly.
• Multiplication: done by repeated addition.
• Division: done by repeated subtraction.

What was Leibniz’s calculating machine?

Leibniz’s machine was a calculating machine invented by Gottfried Wilhelm Leibniz and built in 1694.

• Operations: it could add and, after some changes, it could multiply.
• Special feature: a stepped gear mechanism introduced the digits to be added.

What was Jacquard’s loom?

Jacquard’s loom was a weaving machine, made by Joseph Jacquard, that was controlled by punched cards.

• Program: it was one of the first machines run by a program.
• Control: punched cards controlled the raising of the threads.
• Holes: lines of holes on a card represented the weaving pattern.
• Effect: it changed the weaving industry.

What was Babbage’s analytical machine?

The analytical machine was a general-purpose calculating machine designed by Charles Babbage.

• Importance: its design contained ideas found in modern computers, such as input, processing, storage and output.
• Title: Babbage is often called the father of the computer.

What was the punched card?

A punched card is a stiff card in which holes are punched to represent data and characters.

• Development: the punched card system developed steadily during the years 1920 to 1930.
• Size: a standard card had 80 columns and 12 rows.
• Capacity: each column held one character, so a card held a maximum of 80 characters.
• Coding: one, two or three holes punched in a column represented a character.
• Punching: a punch machine with a typewriter-like keyboard made the holes in a blank card.
• Inventor link: Herman Hollerith’s machines read punched cards.

What was von Neumann’s machine?

Von Neumann’s machine was an electronic computer design in which the program is stored in the computer’s memory.

• Stored program: instructions and data are kept in the same memory.
• Effect: the computer can run different programs without being rebuilt.

What are the number systems used to represent data?

There are four number systems used to represent data: decimal, binary, octal and hexadecimal.

• Need: to use the computer effectively, you must know how data is represented and communicated.

Evaluation

1. Who invented the Pascaline, and in what year?
2. What was Napier’s bones used for?
3. Describe the parts of an abacus.
4. How many columns and rows did a standard punched card have?
5. Name the four number systems used to represent data.

Assignment

Choose any two early calculating devices. For each, state who invented it, how it worked and what it was used for. Then list the four number systems with their bases.