UNIT 1
1)Discuss briefly five generations of electronic computers
A computer is an electronic device that manipulates information or data.
It has the ability to store, retrieve, and process data.
Nowadays, a computer can be used to type documents, send email, play
games, and browse the Web.
It can also be used to edit or create spreadsheets, presentations, and
even videos. But the evolution of this complex system started around
1946 with the first Generation of Computer and evolving ever since.
There are five generations of computers.
1. FIRST GENERATION
Introduction:
1. 1946-1959 is the period of first generation computer.
2. J.P.Eckert and J.W.Mauchy invented the first successful electronic
computer called ENIAC, ENIAC stands for “Electronic Numeric
Integrated And Calculator”.
Few Examples are:
1. ENIAC
2. EDVAC
3. UNIVAC
4. IBM-701
5. IBM-650
Advantages:
1. It made use of vacuum tubes which are the only electronic component
available during those days.
2. These computers could calculate in milliseconds.
Disadvantages:
1. These were very big in size, weight was about 30 tones.
2. These computers were based on vacuum tubes.
3. These computers were very costly.
4. It could store only a small amount of information due to the presence
of magnetic drums.
5. As the invention of first generation computers involves vacuum tubes,
so another disadvantage of these computers was, vacuum tubes
require a large cooling system.
6. Very less work efficiency.
7. Limited programming capabilities and punch cards were used to take
inputs.
8. Large amount of energy consumption.
9. Not reliable and constant maintenance is required.
2. SECOND GENERATION
Introduction:
1. 1959-1965 is the period of second-generation computer.
2. 3.Second generation computers were based on Transistor instead of
vacuum tubes.
Few Examples are:
1. Honeywell 400
2. IBM 7094
3. CDC 1604
4. CDC 3600
5. UNIVAC 1108
Advantages:
1. Due to the presence of transistors instead of vacuum tubes, the size
of electron component decreased. This resulted in reducing the size
of a computer as compared to first generation computers.
2. Less energy and not produce as much heat as the first genration.
3. Assembly language and punch cards were used for input.
4. Low cost than first generation computers.
5. Better speed, calculate data in microseconds.
6. Better portability as compared to first generation
Disadvantages:
1. A cooling system was required.
2. Constant maintenance was required.
3. Only used for specific purposes.
3. THIRD GENERATION
Introduction:
1. 1965-1971 is the period of third generation computer.
2. These computers were based on Integrated circuits.
3. IC was invented by Robert Noyce and Jack Kilby In 1958-1959.
4. IC was a single component containing number of transistors.
Few Examples are:
1. PDP-8
2. PDP-11
3. ICL 2900
4. IBM 360
5. IBM 370
Advantages:
1. These computers were cheaper as compared to second-generation
computers.
2. They were fast and reliable.
3. Use of IC in the computer provides the small size of the computer.
4. IC not only reduce the size of the computer but it also improves the
performance of the computer as compared to previous computers.
5. This generation of computers has big storage capacity.
6. Instead of punch cards, mouse and keyboard are used for input.
7. They used an operating system for better resource management and
used the concept of time-sharing and multiple programming.
8. These computers reduce the computational time from microseconds to
nanoseconds.
Disadvantages:
1. IC chips are difficult to maintain.
2. The highly sophisticated technology required for the manufacturing of
IC chips.
3. Air conditioning is required.
4. FOURTH GENERATION
Introduction:
1. 1971-1980 is the period of fourth generation computer.
2. This technology is based on Microprocessor.
3. A microprocessor is used in a computer for any logical and arithmetic
function to be performed in any program.
4. Graphics User Interface (GUI) technology was exploited to offer
more comfort to users.
Few Examples are:
1. IBM 4341
2. DEC 10
3. STAR 1000
4. PUP 11
Advantages:
1. Fastest in computation and size get reduced as compared to the
previous generation of computer.
2. Heat generated is negligible.
3. Small in size as compared to previous generation computers.
4. Less maintenance is required.
5. All types of high-level language can be used in this type of computers.
Disadvantages:
1. The Microprocessor design and fabrication are very complex.
2. Air conditioning is required in many cases due to the presence of ICs.
3. Advance technology is required to make the ICs.
5. FIFTH GENERATION
Introduction:
1. The period of the fifth generation in 1980-onwards.
2. This generation is based on artificial intelligence.
3. The aim of the fifth generation is to make a device which could
respond to natural language input and are capable of learning and self-
organization.
4. This generation is based on ULSI(Ultra Large Scale Integration)
technology resulting in the production of microprocessor chips having
ten million electronic component.
Few Examples are:
1. Desktop
2. Laptop
3. NoteBook
4. UltraBook
5. Chromebook
Advantages:
1. It is more reliable and works faster.
2. It is available in different sizes and unique features.
3. It provides computers with more user-friendly interfaces with
multimedia features.
Disadvantages:
1. They need very low-level languages.
2. They may make the human brains dull and doomed.
1)what is computer architecture? Explain the Flynn’s classification of computer
architecture?
Computer architecture is a specification detailing how a set of software
and hardware technology standards interact to form a computer system
or platform. In short, computer architecture refers to how a computer
system is designed and what technologies it is compatible with.
M.J. Flynn proposed a classification for the organization of a computer
system by the number of instructions and data items that are
manipulated simultaneously.
The sequence of instructions read from memory constitutes
an instruction stream.
The operations performed on the data in the processor constitute a data
stream.
Parallel processing may occur in the instruction stream, in the data
stream, or both.
SISD
SISD stands for 'Single Instruction and Single Data Stream'. It
represents the organization of a single computer containing a control unit,
a processor unit, and a memory unit.
Instructions are executed sequentially, and the system may or may not
have internal parallel processing capabilities.
Most conventional computers have SISD architecture like the traditional
Von-Neumann computers.
Parallel processing, in this case, may be achieved by means of multiple
functional units or by pipeline processing.
1. Where, CU = Control Unit, PE = Processing Element, M = Memory
Instructions are decoded by the Control Unit and then the Control Unit sends the
instructions to the processing units for execution. Data Stream flows between the
processors and memory bi-directionally.
Examples: Older generation computers, minicomputers, and workstations
SISD
SISD stands for 'Single Instruction and Single Data Stream'. It
represents the organization of a single computer containing a control unit,
a processor unit, and a memory unit.
Instructions are executed sequentially, and the system may or may not
have internal parallel processing capabilities.
Most conventional computers have SISD architecture like the traditional
Von-Neumann computers.
Parallel processing, in this case, may be achieved by means of multiple
functional units or by pipeline processing.
1. Where, CU = Control Unit, PE = Processing Element, M = Memory
Instructions are decoded by the Control Unit and then the Control Unit sends
the instructions to the processing units for execution. Data Stream flows
between the processors and memory bi-directionally.
Examples: Older generation computers, minicomputers, and workstations
SIMD
SIMD stands for 'Single Instruction and Multiple Data Stream'. It
represents an organization that includes many processing units under the
supervision of a common control unit.
All processors receive the same instruction from the control unit but
operate on different items of data.
The shared memory unit must contain multiple modules so that it can
communicate with all the processors simultaneously.
SIMD is mainly dedicated to array processing machines. However, vector
processors can also be seen as a part of this group.
MISD
MISD stands for 'Multiple Instruction and Single Data stream'.
MISD structure is only of theoretical interest since no practical system
has been constructed using this organization.
In MISD, multiple processing units operate on one single-data stream.
Each processing unit operates on the data independently via separate
instruction stream.
1. Where, M = Memory Modules, CU = Control Unit, P = Processor Units
Example:
The experimental Carnegie-Mellon C.mmp computer (1971)
MIMD
MIMD stands for 'Multiple Instruction and Multiple Data Stream'.
In this organization, all processors in a parallel computer can execute
different instructions and operate on various data at the same time.
In MIMD, each processor has a separate program and an instruction
stream is generated from each program.
1. Where, M = Memory Module, PE = Processing Element, and CU = Control Unit
Examples:
Cray T90, Cray T3E, IBM-SP2
1. C) A 60 MHz processor executes a benchmark program with
following instruction
Mix and clock cycle count. Determine 1)CPI 2)MIPS
Instruction Type Instruction Count Clock cycle count
Integer 40%(40,000) 1
Data transfer 30%(30,000) 2
FP 10%(10,000) 4
Control 10%(10,000) 8
Ans. CPI= (0.4*1+0.3*2+0.1*4+0.1*8) =2.2
6
MIPS = clock rate/CPI x 10
= 60 x 106/2.2 x 10 6
=27.27
