A computer is an electronics machine that accepts the instructions from user, converts them into digital-form, does the mathematical calculations and finally displays the result or output on some screen. Said that, the computer consists of various parts and these computer components communicate with each other to perform the calculations based on our instructions.
Classification of computers
Before the digital version of computers, the first computer invented by Charles Baggage (father of computers) was mechanical in nature. It was designed for defense services to do navigational calculations. Later in the 20th century, the non-programmable analog computer was developed. The latest in the hierarchy are the electronics or digital computers and these modern day computers are classified as below.
Block diagram of Computer
As you can see in the figure above there are four basic components of the computer and neither of these computer components communicate with each other directly. All these components communicate either in uni-direction or bi-directionally with the heart of computer called CPU or commonly called processor.
Input Devices. These are the devices that are used to feed the instructions (input by the user) to the CPU (Central Processing Unit) for processing. The most common input devices of the computer are
- Barcode scanner
Output Devices. The devices that present the results of your instructions in some form are called output devices of the computer. Some of the output devices are
- Printers (Laser/Inkjet/Dot-matrix/3D)
- Monitors (CRT/LCD/LED/TV)
- Braille readers
Memory. These are the computer components that are used to store the data or programs either on the temporary or permanent basis. There are primarily two types of memory that are found on a computer.
- ROM (Read only memory) is a permanent memory
- RAM (Random Access memory) is a volatile or temporary memory
Storage Devices. These devices are used to store the data or the work done by you. These storage devices communicate in both directions with CPU. You can send the data to these devices or the CPU can receive the data as well. Some of the storage devices are.
- Hard disk drive
- Floppy Disk Drive
- External USB drive