The LEO was a series of early computer systems created by J. Lyons and Co. The first in the series, the LEO I, was the first computer used for commercial business applications.
A circuit board from a LEO III computer
A computer is a machine that can be programmed to automatically carry out sequences of arithmetic or logical operations (computation). Modern digital electronic computers can perform generic sets of operations known as programs. These programs enable computers to perform a wide range of tasks. The term computer system may refer to a nominally complete computer that includes the hardware, operating system, software, and peripheral equipment needed and used for full operation; or to a group of computers that are linked and function together, such as a computer network or computer cluster.
A human computer, with microscope and calculator, 1952
The Ishango bone, a bone tool dating back to prehistoric Africa
The Antikythera mechanism, dating back to ancient Greece circa 150–100 BCE, is an early analog computing device.
Charles Babbage c. 1850