JSS1 Computer Studies Lesson Note on Mechanical Counting Devices

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TOPIC:  HISTORICAL DEVELOPMENT OF COMPUTERS:

CONTENT: 

Mechanical Counting/Calculating Devices

As a result of the disadvantages of the early counting devices, more advanced mechanical counting/calculating devices were invented. Some of these devices are;

• Abacus (Chinese)
• Napier’s Bone (John Napier)
• Slide Rule (William Oughtred)

THE ABACUS

The Abacus is made up of beads threaded on iron rods. The iron rods are fixed to a rectangular wooden frame. It is used for addition and subtraction only. It could not carry out complex mathematics.  The Abacus was early used for arithmetic tasks, it was developed in China about 5000 years ago. It was successful that its use spread from china to many other countries.

NAPIER’S BONE

After the Abacus, the next significant development was Napier’s Bone by John Napier in 1617. John Napier was a Scottish mathematician, physicist, and astronomer. He is best known as the discoverer of logarithms. He also made common the use of the decimal point in arithmetic and mathematics. Napier’s bone is a manually-operated calculating device for calculation of products and quotients of numbers.

Using the multiplication tables embedded in the rods, multiplication can be reduced to addition operations and division to subtractions. More advanced use of the rods can even extract square roots. Note that Napier’s bone is not the same as logarithms, with which Napier’s name is also associated. The complete device usually includes a base board with a rim; the user places Napier’s rods inside the rim to conduct multiplication or division. The board’s left edge is divided into 9 squares, holding the numbers 1 to 9. The Napier’s rod consists of strips of wood, metal or heavy cardboard. Napier’s bone is three-dimensional, square in cross section, with four different rods engraved on each one. A set of such bones might be enclosed in a convenient carrying case.

SLIDE RULE

The slide Rule which is also called the slip-stick in the United States of America was invented around 1620-1630 shortly after John Napier’s publication of the concept of logarithms. It is a mechanical analogue computer. The slide rule is used primarily for multiplication, division, and also functions such as roots, algorithms and trigonometry, but is not normally used for addition or subtraction.

Slide rules come in diverse range of styles and generally appear in a straight or circular form with a standardized set of markings (scales) essential to performing mathematical computations.

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