SECOND GENERATION COMPUTERS
(ERA OF TRANSISTORS)
1956 - 1964
ERA OF TRANSISTORS
Transistors replaced vacuum tubes and ushered in
the second generation computers.
Transistors are devices composed of semi conductor
material that amplifies, opens and closes a circuit.
Invented in 1947 by three scientists working at AT &
T Bell Labs (John Bardeen, William Shockley and
Walter Brattain). Today’s micro processors contain
millions of microscopic transistors.
DISADVANTAGES OF VACUUM TUBES
Required a great deal of space
Needed to be replaced more often. ENIAC
computers for example had 18000 vacuum
tubes in them; think of the cost of housing
and cooling the system. The transistor had
solved all these problems.
CHARACTERISTICS OF 2ND
Become smaller and Faster (increased processing speed)
Cheaper in terms of production and maintenance (produced
less heat and therefore minimal time for break downs)
More energy efficient and reliable (due to better circuitry)
First computers to store instructions in memory --- moving
away from magnetic drums
Employed assembly language
Employed Assembly language rather than Machine language
employed in the 1st generation computers. They started to
show characteristics of modern computers
The instructions (programs) could be stored inside the
computer memory. High level languages such as COBOL and
FORTRAN were used for programming.
Machine Language: Languages
understood by the machine (almost
impossible for humans to understand)
High Level or Assembly Languages:
Assembly language contains the same
instructions as a machine language, but
the instructions and variables have
names instead of being just numbers.
High-level languages are translated into
assembly language or machine
language by a compiler. Assembly
language programs are translated into
machine language by a program called
1st COMPUTER BUG
Among other developments in this
generation was the founding of the first
computer bug by GRACE MURRAY
She found a moth stuck in a relay which was
responsible for a malfunction; she ultimately
called it DEBUGGING a computer.
THIRD GENERATION: THE ERA OF
INTEGRATED CIRCUITS (1964 – 1974)
Integrated circuits are defined as a single chip
that has thousands (or even millions) of
transistors, resistors and capacitors integrated
Placing a large number of transistors onto a
single chip significantly improved the speed or
power of a single computer and lowered its
CHARACTERISTICS OF THIRD
Smaller computers compared to 2nd generation
User interaction with the help of the operating
system, keyboard and mouse
Multi-tasking (allowing the computer to run
different applications at the same time)
Magnetic tape and Disks replaced Punched
cards as a medium for input and output)
Consumed less power compared to the
previous generation computers
FOURTH GENERATION: THE ERA OF THE
MICROPROCESSOR (1971 –TO DATE
This generation saw the largest scale
integration of computer circuitry. It is
characterized by two principles: development
of monolithic integrated circuits (thousands
or millions of transistors put onto a single
integrated circuit) and the invention of the
microprocessor (a single chip that could do
the processing of a full scale computer).
Microprocessors can as well be defined as
integrated circuits that can interpret, execute
program instructions and handle arithmetic
operations. This makes 4th generation
computers the fastest, smallest and most
Earliest chips developed was the INTEL
4004 Chip developed in 1971
Microprocessors are a defining trait of computers
today, and therefore to choose the best computer for
your needs, you must know their different
CLOCK SPEED (CLOCK RATE)
It’s the speed at which a microprocessor executes
instructions. Every computer contains an internal
clock that regulates the rate at which instructions are
executed and synchronizes all the various computer
Clock speed is stated or measured in either
MHz or GHz... 1 MHz (MEGAHERZ) is equal
to 1 million cycles per second, while 1 GHz
(GIGAHERZ) is equal to 1 billion cycles per
second. HERZ refers to cycles per second.
At present most microprocessors run from
1.8GHz to 3.2 GHz.
Instruction set is the second characteristic of
microprocessors. All possible operations that
can be performed by the microprocessor are
based on the set of its instruction set.
Advanced processors may have more 150 or
200 instruction sets and therefore can have
extremely advanced or complicated tasks.
Pentium 5 has a bigger instruction set than
Pentium 4 machines.
It refers to the high speed storage mechanism
that holds recently read data and instructions
from the main memory. Most programs access
the same information repeatedly while running.
This eliminates the processor from having to
constantly access the main memory which may
slow down the computer system.
Bus speed refers to how many times data can be
transferred over the system Bus per second. It’s
measured in MHz (the same unit used to measure
the clock speed). The processor usually
communicates with other devices through the DATA
BUS. While a processor might be working at up to 3
GHz, quite often the performance of the computer is
hampered by a slower data bus speed. Data bus
speeds range from 200MHz up to 1GHz.
Examples of the earliest 4th
Altair 8800 computer kit in 1975
Apple 2 in 1977
PC from IBM in 1981
In summary, 4th generation computers are
associated with the following characteristics; use of
microprocessors, large scale integration of computer
parts, saw the development of sophisticated
operating systems and more friendly programs,
introduction of computer networks, development of
Graphical User Interfaces (GUI) to name a few.
Computers became more powerful and were applied
in many spheres of life.
FIFTH GENERATION: THE ERA OF
ARTIFICIAL INTELLIGENCE (PRESENT AND
Also known as the future computer
generation, such computing devices are
based on the principle of Artificial Intelligence
and are a rapidly growing technology that is
being researched and applied worldwide.
Artificial intelligence is a field whose major thrusts
are to develop intelligent computer power to
supplement human brain power, and to better
understand how we think, reason and learn.
Artificial Intelligence is therefore a branch of
computer science concerned with making computers
behave like humans, with characteristics such as self
diagnosis and healing, self organizing, visual and
audio input and output and learning from experience.
Various applications of Artificial Intelligence are being developed
every day. These include; Expert Systems, Natural Language
Understanding Systems, Speech Recognition and Understanding
Systems, Robotics, and Computer Vision.
John McCarthy coined the term Artificial Intelligence in the late 1950s
---- and the biggest question of the day then, was, “what possesses
something to have artificial intelligence?”
Intelligence refers to the capacity to acquire and apply knowledge,
while knowledge is defined as familiarity, awareness or
understanding gained through experience or study. Artificial
Intelligence is the ability to acquire and apply an understanding
gained through experience or study in order to mimic "natural
intelligence." This is, in fact, what expert systems are being designed
LIMITATIONS OF ARTIFICIAL
“What makes an expert system seem not truly
intelligent? With today's technology, there are a
number of limitations of expert systems that
might make expert systems appear to some to
be "artificially stupid."
Ability to possess and use common sense
Development of deep reasoning systems
Ability to vary an expert system's explanation
Ability to get expert systems to learn
Ability to have distributed expert systems
Ability to easily acquire and update knowledge