18CSS101J(R) - Programming for Problem Solving
UNIT I
INTRODUCTION
Syllabus
Basic Organization of a Computer System – Number System – Binary – Decimal – Conversion
– Problems – Need for Logical Analysis and Thinking - Algorithm – Pseudo Code – Flow Chart.
Basic Organization of a Computer System
Input Unit Storage Unit Output Unit Results
Control Unit
Central Processing
Unit
Arithmetic Logic
Unit
Input:
• It accepts (or reads) instructions and data from outside world
• It converts these instructions and data in computer acceptable form
• It supplies the converted instructions and data to the computer system for
further processing
Output Unit:
• It accepts the results produced by the computer, which are in coded form and hence,
cannot be easily understood by us .
• It converts these coded results to human acceptable (readable) form.
• It supplies the converted results to outside world
Unit I Page 1
, 18CSS101J(R) - Programming for Problem Solving
Storage Unit:
• Data and instructions required for processing (received from input devices)
• Intermediate results of processing
• Final results of processing, before they are released to an output device
Two Types of Storage
Primary storage:
• Used to hold running program instructions
• Used to hold data, intermediate results, and results of ongoing processing of job(s)
• Fast in operation
• Small Capacity
• Expensive
• Volatile (looses data on power dissipation)
Secondary storage
• Used to hold stored program instructions
• Used to hold data and information of stored jobs
• Slower than primary storage
• Large Capacity
• Lot cheaper that primary storage
• Retains data even without power
Arithmetic Logic Unit (ALU)
Arithmetic Logic Unit of a computer system is the place where the actual executions of
instructions takes place during processing operation.
Control Unit (CU)
Control Unit of a computer system manages and coordinates the operations of all other
components of the computer system.
Central Processing Unit (CPU)
• It is the brain of a computer system.
• It is responsible for controlling the operations of all other units of a computer system.
Unit I Page 2
, 18CSS101J(R) - Programming for Problem Solving
Characteristics of computer
• Automatic: Given a job, computer can work on it automatically without human
interventions.
• Speed: Computer can perform data processing jobs very fast, usually measured in
microseconds (10-6), nanoseconds (10-9), and picoseconds (10-12).
• Accuracy: Accuracy of a computer is consistently high and the degree of its accuracy
depends upon its design. Computer errors caused due to incorrect input data or
unreliable programs are often referred to as Garbage- In-Garbage-Out (GIGO).
• Diligence: Computer is free from monotony, tiredness, and lack of concentration. It
can continuously work for hours without creating any error and without grumbling.
• Versatility: Computer is capable of performing almost any task, if the task can be
reduced to a finite series of logical steps.
• Power of Remembering: Computer can store and recall any amount of information
because of its secondary storage capability. It forgets or looses certain information only
when it is asked to do so.
• No I.Q.: A computer does only what it is programmed to do. It cannot take its own
decision in this regard.
• No Feelings: Computers are devoid of emotions. Their judgments based on the
instructions given to them in the form of programs that are written by us (human
beings).
So What is a Computer?
• The word computer comes from the word “compute”, which means, “to calculate”. Thereby,
a computer is an electronic device that can perform arithmetic operations at high speed. A
computer is also called a data processor because it can store, process, and retrieve data
whenever desired.
• A computer is a system as it comprises of integrated components (input unit, output unit,
storage unit, and CPU) that work together to perform the steps called for in the executing
program.
Unit I Page 3
UNIT I
INTRODUCTION
Syllabus
Basic Organization of a Computer System – Number System – Binary – Decimal – Conversion
– Problems – Need for Logical Analysis and Thinking - Algorithm – Pseudo Code – Flow Chart.
Basic Organization of a Computer System
Input Unit Storage Unit Output Unit Results
Control Unit
Central Processing
Unit
Arithmetic Logic
Unit
Input:
• It accepts (or reads) instructions and data from outside world
• It converts these instructions and data in computer acceptable form
• It supplies the converted instructions and data to the computer system for
further processing
Output Unit:
• It accepts the results produced by the computer, which are in coded form and hence,
cannot be easily understood by us .
• It converts these coded results to human acceptable (readable) form.
• It supplies the converted results to outside world
Unit I Page 1
, 18CSS101J(R) - Programming for Problem Solving
Storage Unit:
• Data and instructions required for processing (received from input devices)
• Intermediate results of processing
• Final results of processing, before they are released to an output device
Two Types of Storage
Primary storage:
• Used to hold running program instructions
• Used to hold data, intermediate results, and results of ongoing processing of job(s)
• Fast in operation
• Small Capacity
• Expensive
• Volatile (looses data on power dissipation)
Secondary storage
• Used to hold stored program instructions
• Used to hold data and information of stored jobs
• Slower than primary storage
• Large Capacity
• Lot cheaper that primary storage
• Retains data even without power
Arithmetic Logic Unit (ALU)
Arithmetic Logic Unit of a computer system is the place where the actual executions of
instructions takes place during processing operation.
Control Unit (CU)
Control Unit of a computer system manages and coordinates the operations of all other
components of the computer system.
Central Processing Unit (CPU)
• It is the brain of a computer system.
• It is responsible for controlling the operations of all other units of a computer system.
Unit I Page 2
, 18CSS101J(R) - Programming for Problem Solving
Characteristics of computer
• Automatic: Given a job, computer can work on it automatically without human
interventions.
• Speed: Computer can perform data processing jobs very fast, usually measured in
microseconds (10-6), nanoseconds (10-9), and picoseconds (10-12).
• Accuracy: Accuracy of a computer is consistently high and the degree of its accuracy
depends upon its design. Computer errors caused due to incorrect input data or
unreliable programs are often referred to as Garbage- In-Garbage-Out (GIGO).
• Diligence: Computer is free from monotony, tiredness, and lack of concentration. It
can continuously work for hours without creating any error and without grumbling.
• Versatility: Computer is capable of performing almost any task, if the task can be
reduced to a finite series of logical steps.
• Power of Remembering: Computer can store and recall any amount of information
because of its secondary storage capability. It forgets or looses certain information only
when it is asked to do so.
• No I.Q.: A computer does only what it is programmed to do. It cannot take its own
decision in this regard.
• No Feelings: Computers are devoid of emotions. Their judgments based on the
instructions given to them in the form of programs that are written by us (human
beings).
So What is a Computer?
• The word computer comes from the word “compute”, which means, “to calculate”. Thereby,
a computer is an electronic device that can perform arithmetic operations at high speed. A
computer is also called a data processor because it can store, process, and retrieve data
whenever desired.
• A computer is a system as it comprises of integrated components (input unit, output unit,
storage unit, and CPU) that work together to perform the steps called for in the executing
program.
Unit I Page 3
