The origin of computers dates back to when our fore fathers used their early calculating devices to count. For example

  1. Counting with fingers and toes: calculations were done by our fore fathers with their toes and fingers before the invention of computers.
  2. Counting with pebbles: when counting with fingers became inadequate the early men later introduced pebbles (stone) to count the number of flocks they had.

Prior to the invention of alternative means for counting, fingers ,toes ,stones and beads were used in counting in the performance of simple arithmetic calculations such as additions and subtractions etc.

This simple way of counting was a difficult to use for large numbers. This early method was in place till the invention of Abacus device.



The Abacus device was invented to replace the manual method (finger/ stone) of counting. The Abacus dates as far back as 500 B.C. It was invented to make calculations easier and to suit various numbers of system. It was used in China, Greece, and Rome etc.

FEATURES AND COMPONENTS OF ABACUS: Abacus generally consists of rectangular wooden frame with horizontal rods. Beads made of stones placed in these rods.

COUNTING WITH ABACUS: Counting is done by shifting the beads from one place to another; it is a hand use device for addition and subtraction. The Abacus consists of several columns. Farthest from the right represents ‘ones’; the next one ‘tens’; then hundreds and so on.

USES OF ABACUS: Abacus was mainly used for addition and subtraction.



The slide rule, also known colloquially in the United States as a slip stick, is a mechanical analog computer. The slide rule is used primarily for multiplication and division, and also for functions such as roots, logarithms and trigonometry, but is not normally used for addition or subtraction. It was invented by William Oughtred.

FEATURES AND COMPONENTS: This device makes use of a cursor, which is moved up and down various scales to perform multiplication and division using the principle of logarithms. The device is similar to today’s calculator.

USES: The slide rule is used mainly for multiplication and division functions.


NAPIERS BONE (features and components)

The next significant development after Abacus came in, was when John Napier a Scottish mathematician developed a device having a set of rods made of bone for calculation involving multiplication.

USES: The Rods had numbers printed on them in order that these numbers would appear in a multiplication table. To perform a multiplication, individual stripes are arranged in order to represent the number to be multiplied. Napeir’s bone is a type of calculator.

PASCAL CALCULATOR: This was invented by Blaise Pascal in the year 1642 when he was only 19 years old. This calculating machine is called Pascaline. Blaise Pascal was a French mathematician.

FEATURES AND COMPONENT: This was the first mechanical digital calculator that could perform addition and subtraction on whole numbers. It consists of clogged wheels, gears. It had a system of interlocking rotating cog wheels. Each wheel had ten segments. When one wheel completes a rotation, the next wheel moves one segment. Numbers 0 to 9 are there on the circumference on the top row of eight movable of the wheel.

USES: this was the first mechanical digital calculator that could perform addition and subtraction on whole numbers. Pascal calculator is also called Pascaline or the Arithmetique.



A German Gottfried Von Lebuiz famous mathematician invented Leibuizs multiplier. This is made up of wheel. The machine is about 67 cm (26 inches) long, made of polished brass and steel, mounted in an oak case.

USES: Leibuiz multiplier allowed long multiplication and division to be done. The process of multiplication involved repeated addition.




·      List the different pre computing devices?

·      State the components in each of the device mentioned above?

·      State what each device was used for in those days?

Teacher gives correction on the evaluation test and summarizes the lesson. Teacher allows students to ask question to for better understanding and to clear doubt.


1.      Describe what an Abacus looks like and its use

2.      State the components the slide rule, Pascal calculator is made of

3.      Make a research online on  Jacquards 100m and Charles babbage


See also

Computer Hardware and Software

Constituents Parts of a Computer System

Logic Gate

Logic Gate

Logic Circuit


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