The document provides information on computer organization and architecture. It discusses the basic characteristics of computers such as speed, accuracy, reliability, versatility, and others. It also covers the classification of computers according to functionality, purpose, and size. The key structural components of a computer are described as the central processing unit (CPU), main memory, input/output (I/O), and interconnect system. The CPU contains a control unit, arithmetic logic unit (ALU), and registers. Computer organization refers to how the operational units are interconnected, while computer architecture describes the attributes visible to programmers.

1. Computer Organization

2. Characteristics of Computer
Basic characteristics about computer are:
• Speed : A powerful computer is capable of
executing about 3 million calculations per
second.
• Accuracy(wbuLyZ) : A computer's accuracy is
consistently high; if there are errors, they are due
to errors in instructions given by the programmer.
• Reliability(wbf©i‡hvM¨) : The output generated by
the computer is very reliable as long as the data is
reliable.

3. Characteristics of Computer
Basic characteristics about computer are:
• Versatility(PÂjZv): The computer can accomplish many
different things. It can accept information through various
input-output devices, perform arithmetic and logic
operations, generate a variety of outputs in a variety of
forms, etc.
• Automation: Once the instructions are fed into computer it
works automatically without any human intervention.
• Diligence(Aa¨emvq): A computer will never fail to perform its
task due to distraction or laziness.
• Convenience(myweav): Computers are usually easy to
access, and allow people to find information easily that
without a computer would be very difficult.

4. Characteristics of Computer
Basic characteristics about computer are:
• Flexibility: Computers can be used for
entertainment, for business, by people who hold
different ideals or who have varied goals. Almost
anyone can use a computer, and computers can
be used to assist with almost any goal.
• Repetitiveness: Computer can work one task
again and again without getting bored.
• Memory/Storage Capacity : The computer can
store large volumes of data and makes the
retrieval of data an easy task.

5. Limitations of Computer
a. No Self Intelligence
A computer is able to do a work which is difficult for man.
Computers are used to do risky and dangerous work and
where sharp actually is needed. But it does not have any
intelligence of its own. It works according to the
instruction only.
b. No Decision-Making power
Computer cannot take any decision of its own. It does only
those tasks which are already instructed to it.
c. No learning power
Computer has no learning power. Once you give
instructions to a computer how to perform a task, the
very task is cannot perform if you do not give it any
instructions for the next time.

6. Classification of Computers
According to functionality/signal, computers are
classified as :
• Analog Computer : An analog computer is a form of
computer that uses continuous physical phenomena
such as electrical, mechanical, or hydraulic quantities
to model the problem being solved.
• Digital Computer: A computer that performs
calculations and logical operations with quantities
represented as digits, usually in the binary number
system.
• Hybrid Computer (Analog + Digital): A combination of
computers those are capable of inputting and
outputting in both digital and analog signals. A hybrid
computer system setup offers a cost effective method
of performing complex simulations.

7. Classification of Computers
According to purpose, computers are classified as :
• A special-purpose computer is designed for a specific
application. It is also known as dedicated computer. Many
such computers have instructions permanently
programmed into them that are designed to perform only
one major function. Special-purpose computers are used to
control traffic lights, to control the collection of tolls on
highways, and in automobiles, weapons, appliances and
games etc.
• General-purpose computers are used to handle a variety of
tasks. By this concept, a program containing a series of
instructions is prepared for an application and temporally
stored in memory. Once stored in the computer’s memory,
the program can be executed to perform the specific
function. After the completion of the execution of one
program, another program can be used for some other
task.

8. Classification of Computers
On the basis of Size/Capacity
• Super Computer: The fastest and most powerful type of
computer, Supercomputers are very expensive and are
employed for specialized applications that require immense
amounts of mathematical calculations. For example,
weather forecasting requires a supercomputer. Other uses
of supercomputers include animated graphics, fluid
dynamic calculations, nuclear energy research, and
petroleum exploration.
• Mainframe Computer: A very large and expensive
computer capable of supporting hundreds, or even
thousands, of users simultaneously. In some ways,
mainframes are more powerful than supercomputers
because they support more simultaneous programs. But
supercomputers can execute a single program faster than a
mainframe.

9. Supercomputer in NASA

10. Classification of Computers
• Mini Computer: In size and power, minicomputers lie between
workstations and mainframes. In the past decade, the distinction
between large minicomputers and small mainframes has blurred.
But in general, a minicomputer is a multiprocessing system capable
of supporting from 4 to about 200 users simultaneously.
• Micro Computer or Personal Computer
• Desktop Computer: A personal or micro-mini computer sufficient to
fit on a desk.
• Laptop Computer: A portable computer complete with an
integrated screen and keyboard. It is generally smaller in size than a
desktop computer and larger than a notebook computer.
• Palmtop Computer/Digital Diary /Notebook /PDAs(Personal
Digital Assistant): A hand-sized computer. Palmtops have no
keyboard but the screen serves both as an input and output device.
• Workstations: A terminal or desktop computer in a network. In this
context, workstation is just a generic term for a user's machine
(client machine) in contrast to a "server" or "mainframe."

11. Classification of Computers

12. What are the differences between
supercomputer and mainframe Computer?

13. What are the differences between
supercomputer and mainframe Computer?
• The chief difference between
a supercomputer and a
mainframe is that a
supercomputer channels all
its power into executing a few
programs as fast as possible,
whereas a mainframe uses its
power to execute many
programs concurrently.

14. Computer Organization
• Computer organization refers to the
operational unites of a computer and their
interconnections that realize the architectural
specifications. These include
-Control system
-interfaces between the computer and its
peripherals
-memory technology used, etc

15. Computer Organization

16. Computer Architecture
• Architecture refers to the attributes of a
computer that are visible to the programmer
and they have a direct impact on logical
execution of a program.

17. Computer Architecture/Structure

19. Computer Structure
Four main structural components are
1. Central processing unit (CPU): Controls the
operation of the computer and performs its
data processing functions; often simply
referred to as processor.
2. Main memory: Stores data.
3. I/O: Moves data between the computer
and its external environment.
4. System interconnection: Some mechanism
that provides for communication among
CPU, main memory, and I/O.

20. Main Structural components of the
CPU:
1. Control Unit: Controls
the operation of the CPU
and hence the computer.
2. Arithmetic and Logic
Unit (ALU): Performs the
computer's data
processing functions.
3. Registers: Provides
storage internal to the
CPU.
4. CPU Interconnection:
Some mechanism that
provides for
communication among
the control unit, ALU, and
registers.

21. Registers use in computer
• Memory buffer register (MBR):Contains a word to be stored in
memory or sent to the I/O unit, or is used to receive a word from
memory or from the I/O unit.
• Memory address register (MAR):Specifies the address in memory of
the word to be written from or read into the MBR.
• Instruction register (IR): Contains the 8-bit opcode instruction being
executed.
• Instruction buffer register (IBR): Employed to hold temporarily the
right-hand instruction from a word in memory.
• Program counter (PC):Contains the address of the next instruction pair
to be fetched from memory.
• Accumulator (AC) and multiplier quotient (MQ): Employed to hold
tem-porarily operands and results of ALU operations. For example, the
result of multiplying two 40-bit numbers is an 80-bit number; the most
significant 40 bits are stored in the AC and the least significant in the
MQ.

23. Getting bored?
Good news is enough for today!