OUTPUT DEVICES: An output device is any piece of computer hardware that is used to output data that has been previously entered into a computer or similar processing device.

ELECTRONIC COUNTING DEVICE

Electronic counting devices are the modern computer. The electronic counting devices are as follows:

Herman Hollerith Punch Card
John Von Neumann Machine
Modern Computer.

Electro-mechanical counting devices are those counting devices that could be operated both electrically and mechanically

These includes the following

Blaise Pascal Machine
Gottfried Leibniz Machine
Joseph Jacquard Loom
Charles Babbage Analytical Engine

OUTPUT DEVICES:  There are the physical components of a computer used to obtain results from computer after processing. There devices convert data from machine-readable format into human-readable format.
Examples:
(a) Monitor (b) Printer (c) Plotter (d) Speaker (e) Projector (f) Microfilm, etc.

KEYS ON KEYBOARD

A keyboard is an input device that resemble a typewriter, which is used to type text, numbers, symbols, commands and to give instructions to the computer.

Alphanumeric keys: These are used to type letters and numbers, the letters A – Z, a – z and the digital 0 – 9.

INPUT DEVICES

An input device is a peripheral (piece of computer hardware equipment) used to provide data and control signals to an information processing system such as a computer or information appliance. Examples of input devices include keyboard, mouse, scanners, digital cameras and joysticks, etc.