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

Generations of Computers

First Generation (1940-1956) Vacuum Tubes

The first computers used vacuum tubes for circuitry and magnetic drums for memory, and were often enormous, taking up entire rooms. They were very expensive to operate and in addition to using a great deal of electricity, generated a lot of heat, which was often the cause of malfunctions.

First generation computers relied on machine language, the lowest-level programming language understood by computers, to perform operations, and they could only solve one problem at a time. Input was based on punched cards and paper tape, and output was displayed on printouts.

The UNIVAC and ENIAC computers are examples of first-generation computing devices. The UNIVAC was the first commercial computer delivered to a business client, the U.S. Census Bureau in 1951.

First Generation Computers

Second Generation (1956-1963) Transistors

Transistors replaced vacuum tubes and ushered in the second generation of computers. The transistor was invented in 1947 but did not see widespread use in computers until the late 1950s. The transistor was far superior to the vacuum tube, allowing computers to become smaller, faster, cheaper, more energy-efficient and more reliable than their first-generation predecessors. Though the transistor still generated a great deal of heat that subjected the computer to damage, it was a vast improvement over the vacuum tube. Second-generation computers still relied on punched cards for input and printouts for output.

Second-generation computers moved from cryptic binary machine language to symbolic, or assembly, languages, which allowed programmers to specify instructions in words. High-level programming languages were also being developed at this time, such as early versions of COBOL and FORTRAN. These were also the first computers that stored their instructions in their memory, which moved from a magnetic drum to magnetic core technology.

The first computers of this generation were developed for the atomic energy industry.

Second Generation Computers

Third Generation (1964-1971) Integrated Circuits

The development of the integrated circuit was the hallmark of the third generation of computers. Transistors were miniaturized and placed on silicon chips, called semiconductors, which drastically increased the speed and efficiency of computers.

Instead of punched cards and printouts, users interacted with third generation computers through keyboards and monitors and interfaced with an operating system, which allowed the device to run many different applications at one time with a central program that monitored the memory. 

Computers for the first time became accessible to a mass audience because they were smaller and cheaper than their predecessors.

Third Generation : Integrated Circuits

Fourth Generation (1971-Present) Microprocessors

The microprocessor brought the fourth generation of computers, as thousands of integrated circuits were built onto a single silicon chip. What in the first generation filled an entire room could now fit in the palm of the hand. The Intel 4004 chip, developed in 1971, located all the components of the computer—from the central processing unit and memory to input/output controls—on a single chip.

In 1981 IBM introduced its first computer for the home user, and in 1984 Apple introduced the Macintosh. Microprocessors also moved out of the realm of desktop computers and into many areas of life as more and more everyday products began to use microprocessors.

As these small computers became more powerful, they could be linked together to form networks, which eventually led to the development of the Internet. Fourth generation computers also saw the development of GUIs, the mouse and handheld devices.

Fourth Generation : Microprocessors

Fifth Generation (Present and Beyond) Artificial Intelligence

Fifth generation computing devices, based on artificial intelligence, are still in development, though there are some applications, such as voice recognition, that are being used today. The use of parallel processing and superconductors is helping to make artificial intelligence a reality. Quantum computation and molecular and nanotechnology will radically change the face of computers in years to come. The goal of fifth-generation computing is to develop devices that respond to natural language input and are capable of learning and self-organization.

Fifth Generation : Artificial Intelligence