GENERATIONS OF COMPUTER:
The computer has
evolved from a large-sized simple calculating machine to a smaller but much
more powerful machine. The evolution of computer to the current state is
defined in terms of the generations of computer. Each generation of computer is
designed based on a new technological development, resulting in better, cheaper
and smaller computers that are more powerful, faster and efficient than their
predecessors.
Currently, there are
five generations of computer. We will discuss the generations of computer in
terms of:
·
The
technology used by them (hardware and software),
·
Computing
characteristics (speed, i.e., number of instructions executed per second),
·
Physical
appearance, and
·
Their
applications.
First Generation (1940 to 1956): Using Vacuum Tubes
Hardware Technology:
The first generation
of computers used vacuum tubes for circuitry and magnetic drums for memory. The
input to the computer was through punched cards and paper tapes. The output was
displayed as printouts.
Fig: Vacuum tube
Software Technology:
The instructions were
written in machine language. Machine language uses 0s and 1s for coding of the
instructions. The first generation computers could solve one problem at a time.
Computing
Characteristics:
The computation time
was in milliseconds.
Physical Appearance:
These computers were
enormous in size and required a large room for installation.
Application:
They were used for
scientific applications as they were the fastest computing device of their
time.
Examples:
UNIVersal Automatic
Computer (UNIVAC), Electronic Numerical Integrator And Calculator (ENIAC), and
Electronic Discrete Variable Automatic Computer (EDVAC).
Disadvantages:
The first generation
computers used a large number of vacuum tubes and thus generated a lot of heat.
They consumed a great deal of electricity and were expensive to operate. The
machines were prone to frequent malfunctioning and required constant maintenance.
Since first generation computers used machine language, they were difficult to
program.
Second Generation (1956 to 1963): Using Transistors
Hardware Technology:
Transistors replaced
the vacuum tubes of the first generation of computers. Transistors allowed
computers to become smaller, faster, cheaper, energy efficient and reliable.
The second generation computers used magnetic core technology for
primary memory. They used magnetic tapes and magnetic disks for secondary
storage. The input was still through punched cards and the output using
printouts. They used the concept of a stored program, where instructions were
stored in the memory of computer.
Fig: Transistors
Software Technology:
The instructions were
written using the assembly language. Assembly language uses mnemonics like ADD for addition and SUB
for subtraction for coding of the instructions. It is easier to write
instructions in assembly language, as compared to writing instructions in
machine language. High-level programming languages, such as early versions of
COBOL and FORTRAN were also developed during this period.
Computing
Characteristics:
The computation time
was in microseconds.
Physical Appearance:
Transistors are
smaller in size compared to vacuum tubes, thus, the size of the computer was
also reduced.
Application:
The cost of
commercial production of these computers was very high, though less than the
first generation computers. The transistors had to be assembled manually in
second generation computers.
Examples:
PDP-8, IBM 1401, and CDC 1604.
Disadvantages:
Second generation
computers generated a lot of heat but much less than the first generation
computers. They required less maintenance than the first generation computers.
Third Generation (1964 to 1971): Using Integrated Circuits
Hardware Technology:
The third generation
computers used the Integrated Circuit (IC) chips. In an IC chip,
multiple transistors are placed on a silicon chip. Silicon is a type of
semiconductor. The use of IC chip increased the speed and the efficiency of
computer, manifold. The keyboard and monitor were used to interact with the
third generation computer, instead of the punched card and printouts.
Fig: IC chips
Software Technology:
The keyboard and the
monitor were interfaced through the Operating System. Operating system
allowed different applications to run at the same time. High-level languages
were used extensively for programming, instead of machine language and
assembly language.
Computing
Characteristics:
The computation time
was in nanoseconds.
Physical Appearance:
The size of these
computers was quite small compared to the second generation computers.
Application:
Computers became
accessible to mass audience. Computers were produced commercially, and were
smaller and cheaper than their predecessors.
Examples:
IBM 370, PDP 11.
Advantages:
The third generation
computers used less power and generated less heat than the second generation
computers. The cost of the computer reduced significantly, as individual
components of the computer were not required to be assembled manually. The
maintenance cost of the computers was also less compared to their predecessors.
Fourth Generation (1971 to present): Using Microprocessors
Hardware Technology:
They use the Large
Scale Integration (LSI) and the Very Large Scale Integration (VLSI) technology.
Thousands of transistors are integrated on a small silicon chip using LSI
technology. VLSI allows hundreds of thousands of components to be integrated in
a small chip. This era is marked by the development of microprocessor.
Microprocessor is a chip containing
millions of transistors and components, and, designed using LSI and VLSI
technology. This generation of computers gave rise to Personal Computer (PC).
Semiconductor memory
replaced the earlier magnetic core memory, resulting in fast random access to
memory. Secondary storage device like magnetic disks became smaller in physical
size and larger in capacity. The linking of computers is another key
development of this era. The computers were linked to form networks that led to
the emergence of the Internet. This generation also saw the development of
pointing devices like mouse, and handheld devices.
Fig: Microprocessors
Software Technology:
Several new operating
systems like the MS-DOS and MS-Windows developed during this time. This
generation of computers supported Graphical User Interface (GUI). GUI is
a user-friendly interface that allows user to interact with the computer via
menus and icons. High-level programming languages are used for the writing of
programs.
Computing
Characteristics:
The computation time
is in picoseconds.
Physical Appearance:
They are smaller than
the computers of the previous generation. Some can even fit into the palm of
the hand.
Application:
They became widely
available for commercial purposes. Personal computers became available to the
home user.
Examples:
The Intel 4004 chip
was the first microprocessor. The components of the computer like Central
Processing Unit (CPU) and memory were located on a single chip. In 1981, IBM
introduced the first computer for home use. In 1984, Apple introduced the
Macintosh. The microprocessor has resulted in the fourth generation computers
being smaller and cheaper than their predecessors. The fourth generation
computers are also portable and more reliable.
They generate much
lesser heat and require less maintenance compared to their predecessors.GUI and
pointing devices facilitate easy use and learning on the computer. Networking
has resulted in resource sharing and communication among different computers.
Fifth Generation (Present and Next): Using Artificial Intelligence
The goal of fifth
generation computing is to develop computers that are capable of learning and
self-organization. The fifth generation computers use Super Large Scale
Integrated (SLSI) chips that are able to store millions of components on a
single chip. These computers have large memory requirements. This generation of
computers uses parallel processing that allows several instructions to
be executed in parallel, instead of serial execution.
Parallel processing
results in faster processing speed. The Intel Dual Core microprocessor uses
parallel processing. The fifth generation computers are based on Artificial
Intelligence (AI). They try to simulate the human way of thinking and
reasoning. Artificial Intelligence includes areas like Expert System (ES), Natural
Language Processing (NLP), speech recognition, voice recognition, robotics,
etc.
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