# The history of the calculator

If you need an illustration of the accelerating speed of technological change, look no further than the **electronic calculator**, that modest little device that does the most
complex sum instantly and that you hold in the palm of your hand.

Or more likely don't any more... for the pocket calculator, which took more than four millennia to evolve and only reached its current form in the 1990s, is already obsolescent, if not actually obsolete.

The **history of the calculator** is split into four pages - one for each chapter:

- Beginnings: The Mechanical Age
- Business Calculator: The Electronic Age
- Pocket Calculator: The Microchip Age
- Calculators Now: The Virtual Age

## Beginnings: The Mechanical Age

*The Abacus: Bean counter's friend*

In the very beginning, of course was the **abacus**, a sort of hand operated mechanical calculator using beads on rods, first used by Sumerians and Egyptians around
2000 BC.

The principle was simple, a frame holding a series of rods, with ten sliding beads on each. When all the beads had been slid across the first rod, it was time to move one across on the next, showing the number of tens, and thence to the next rod, showing hundreds, and so on (with the ten beads on the initial row returned to the original position).

It made addition and subtraction faster and less error-prone and may have led to the term 'bean counters' for accountants.

But that was where the technology more or less stuck for the next 3,600 years, until the beginning of the 17th century AD, when the first mechanical calculators began to appear in Europe. Most notably, the development of logarithms by John Napier allowed Edward Gunter, William Oughtred and others to develop the slide rule.

*The Slide Rule: good enough for Dr. Strangelove*

The **slide rule** is basically a sliding stick (or discs) that uses logarithmic scales to allow rapid multiplication and division. Slide rules evolved to allow advanced trigonometry and logarithms, exponentials and square roots.

Even up to the 1980s, knowing how to operate a slide rule was a basic part of mathematics education for millions of schoolchildren, even though by that time, mechanical and electric calculating machines were well established. The problem was that these weren't portable while the slide rule fitted into the breast pocket of your button-down shirt.

Real Rocket Scientists used slide rules to send Man to the Moon - a Pickett model N600-ES was taken on the Apollo 13 moon mission in 1970.

### Gears, Wheels and Buttons

The first mechanical calculator appeared in 1642, the creations of French intellectual and mathematics whizz kid Blaise **Pascal** as "a device that will eventually
perform all four arithmetic operations without relying on human intelligence."

Pascal's machine used geared wheels and could add and subtract two numbers directly and multiply and divide by repetition. Gottfried Leibniz then spent the best part of his life designing a four-operation mechanical calculator, based on his ingenious slotted 'Leibniz wheel,' but ultimately failing to produce a fully operational machine.

*The Arithmometer: Soldiered on till 1915*

That had to wait until 1820 and the patenting in France of Thomas de Colmar's four function **Arithmometer**.

This first commercially viable counting machine was manufactured from 1851 to 1915 and copied by around 20 companies across Europe.

By then, the main tide of innovation had moved across the Atlantic, with the development of hand cranked adding machines like the **Grant Mechanical Calculating
Machine** of 1877 and, more famously the **P100 Burroughs Adding Machine** developed by William Seward Burroughs in 1886.

This was the first in a line of office calculating machines that made the Burroughs family fortune and enabled the son, William S. Burroughs, to pursue a career consuming hallucinogenic drugs and writing subversive novels like 'The Naked Lunch'.

*The Comptometer: Press key calculating at last*

A further step forward occurred in 1887 when Dorr. E. Felt's US-patented key driven '**Comptometer**' took calculating into the push button age. This machine, too,
spurred a host of imitators.

The **Curta calculator**, which first appeared in 1948, was perhaps the ultimate expression of the mechanical calculator, so compact that it could, somewhat lumpily,
fit into a pocket and capable of addition, subtraction, multiplication and division.

Machines like this ensured that mechanical calculators dominated 20th century office life all the way through to the late 1960s. By then, electronics were beginning to take over, as we shall see in the next part of this series.

*Curta calculator: mechanical could be compact*

**On the next page** we look at the electronic age and the development of the business calculator.

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Last update: 24 March 2014