Computer Systems

A computer system is the combination of hardware and software. The hardware consists of the physical

components of the computer, such as the monitor or the keyboard. In other words, the parts of the computer
that you can touch are all hardware. “Software” is the term that is used to refer to the programs that run on
the hardware. Neither one is much use without the other, since without hardware you would not be able to run software and without software you would just have an expensive piece of equipment that does nothing.The two main types of software are the operating system and the application programs that run on top of the operating system.

Hardware

Categories of Computer Hardware
There are four main categories of computer hardware:

1. The Central Processing Unit (CPU)
2. Input devices, which allow data to be entered into the computer
3. Output devices, which are used for outputting (“sending out”) data from the computer
4. Storage devices, both primary and backing

The Central Processing Unit (CPU)

As its name suggests, the Central Processing Unit (CPU) is the part of the computer that does the processing. It also controls the transfer of data between memory and the other devices that make up the computer system. The CPU consists of:

• The Control Unit (CU)
• The Arithmetic/Logic Unit (ALU)
• Small, very fast areas of memory. The smallest and fastest memory is in the form of registers. There is also cache, which is larger and slower than the registers but is still much faster than RAM (you do not have to worry too much about these terms)

Input devices

In computing, an input device is any piece of computer hardware equipment used to provide data and control signals to an information processing system such as a computer or other information appliance. examples of input devices are keyboard and mouse

Output devices

An output device is any piece of computer hardware equipment used to communicate the results of data processing carried out by computer to the outside world.


Software
A computer software is a collection of computer programs and related data that provide the instructions for telling a computer what to do and how to do it. In other words, software is a conceptual entity which is a set of computer programs, procedures, and associated documentation concerned with the operation of a data processing system. We can also say software refers to one or more computer programs and data held in the storage of the computer for some purposes.
Computer software is mainly classified into two categories

• Operating Systems
• Application Software

Operating System

System software provides the basic functions for computer usage and helps run the computer hardware and system. It includes a combination of the following:

• Device drivers
• Operating systems
• Servers
• Utilities
• Window systems

Application software

Application software is developed to perform in any task that benefits from computation. It is a broad category, and encompasses software of many kinds, including the internet browser being used to display this page. This category includes:

• Business software
• Databases
• Educational software
• Image editing
• Simulation software
• Spreadsheets
• Telecommunications 
• Video editing software
• Video games
• Word processing