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| File Processing System |
Monday, June 30, 2014
Thursday, June 26, 2014
Helpful information
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Monday, June 23, 2014
Combinational Logic Circuits (Adders, Multiplexers, Demultiplexers etc)
Combinational Logic Circuits
Unlike sequentcial logic blocks whose outputs are dependant on both their present inputs and
their previous output state giving them some form of Memory, the outputs of Combinational
Logic Circuits are only determined by the logical function of their current input state, logic "0"
or logic "1", at any given instant in time as they have no feedback, and any changes to the signals
being applied to their inputs will immediately have an effect at the output. In other words, in a
Combinational Logic Circuit, the output is dependant at all times on the combination of its
inputs and if one of its inputs condition changes state so does the output as combinational circuits
have "no memory", "timing" or "feedback loops".
Combinational Logic
Combinational Logic Circuits are made up from basic logic NAND, NOR or NOT gates that
are "combined" or connected together to produce more complicated switching circuits. These
logic gates are the building blocks of combinational logic circuits. An example of a
combinational circuit is a decoder, which converts the binary code data present at its input into a
number of different output lines, one at a time producing an equivalent decimal code at its
output.
Combinational logic circuits can be very simple or very complicated and any combinational
circuit can be implemented with only NAND and NOR gates as these are classed as
"universal" gates.
The three main ways of specifying the function of a combinational logic circuit are:
1. Boolean Algebra – This forms the algebraic expression showing the operation of the
logic circuit for each input variable either True or False that results in a logic "1"
output.
2. Truth Table – A truth table defines the function of a logic gate by providing a concise
list that shows all the output states in tabular form for each possible combination of input
variable that the gate could encounter.
3. Logic Diagram – This is a graphical representation of a logic circuit that shows the
wiring and connections of each individual logic gate, represented by a specific graphical
symbol, that implements the logic circuit.
The Multiplexer
A data selector, more commonly called a Multiplexer, shortened to "Mux" or "MPX", are
combinational logic switching devices that operate like a very fast acting multiple position rotary
switch. They connect or control, multiple input lines called "channels" consisting of either 2, 4, 8
or 16 individual inputs, one at a time to an output.
The Demultiplexer
The data distributor, known more commonly as a Demultiplexer or "Demux", is the exact
opposite of the Multiplexer we saw in the previous tutorial. The demultiplexer takes one single
input data line and then switches it to any one of a number of individual output lines one at a
time. The demultiplexer converts a serial data signal at the input to a parallel data at its output
lines as shown below.
The Digital Encoder
Unlike a multiplexer that selects one individual data input line and then sends that data to a
single output line or switch, a Digital Encoder more commonly called a Binary Encoder takes
ALL its data inputs one at a time and then converts them into a single encoded output.
So we can say that a binary encoder, is a multi-input combinational logic circuit that
converts the logic level "1" data at its inputs into an equivalent binary code at its
output. Generally, digital encoders produce outputs of 2-bit, 3-bit or 4-bit codes depending
upon the number of data input lines. An "n-bit" binary encoder has 2n input lines and n-bit
output lines with common types that include 4-to-2, 8-to-3 and 16-to-4 line configurations.
The output lines of a digital encoder generate the binary equivalent of the input line whose
value is equal to "1" and are available to encode either a decimal or hexadecimal input pattern
to typically a binary or B.C.D. output code.
Unlike sequentcial logic blocks whose outputs are dependant on both their present inputs and
their previous output state giving them some form of Memory, the outputs of Combinational
Logic Circuits are only determined by the logical function of their current input state, logic "0"
or logic "1", at any given instant in time as they have no feedback, and any changes to the signals
being applied to their inputs will immediately have an effect at the output. In other words, in a
Combinational Logic Circuit, the output is dependant at all times on the combination of its
inputs and if one of its inputs condition changes state so does the output as combinational circuits
have "no memory", "timing" or "feedback loops".
Combinational Logic
Combinational Logic Circuits are made up from basic logic NAND, NOR or NOT gates that
are "combined" or connected together to produce more complicated switching circuits. These
logic gates are the building blocks of combinational logic circuits. An example of a
combinational circuit is a decoder, which converts the binary code data present at its input into a
number of different output lines, one at a time producing an equivalent decimal code at its
output.
Combinational logic circuits can be very simple or very complicated and any combinational
circuit can be implemented with only NAND and NOR gates as these are classed as
"universal" gates.
The three main ways of specifying the function of a combinational logic circuit are:
1. Boolean Algebra – This forms the algebraic expression showing the operation of the
logic circuit for each input variable either True or False that results in a logic "1"
output.
2. Truth Table – A truth table defines the function of a logic gate by providing a concise
list that shows all the output states in tabular form for each possible combination of input
variable that the gate could encounter.
3. Logic Diagram – This is a graphical representation of a logic circuit that shows the
wiring and connections of each individual logic gate, represented by a specific graphical
symbol, that implements the logic circuit.
The Multiplexer
A data selector, more commonly called a Multiplexer, shortened to "Mux" or "MPX", are
combinational logic switching devices that operate like a very fast acting multiple position rotary
switch. They connect or control, multiple input lines called "channels" consisting of either 2, 4, 8
or 16 individual inputs, one at a time to an output.
 |
| Multiplexer Symbol |
The Demultiplexer
The data distributor, known more commonly as a Demultiplexer or "Demux", is the exact
opposite of the Multiplexer we saw in the previous tutorial. The demultiplexer takes one single
input data line and then switches it to any one of a number of individual output lines one at a
time. The demultiplexer converts a serial data signal at the input to a parallel data at its output
lines as shown below.
 |
| 1-to-4 Channel De-multiplexer |
The Digital Encoder
Unlike a multiplexer that selects one individual data input line and then sends that data to a
single output line or switch, a Digital Encoder more commonly called a Binary Encoder takes
ALL its data inputs one at a time and then converts them into a single encoded output.
So we can say that a binary encoder, is a multi-input combinational logic circuit that
converts the logic level "1" data at its inputs into an equivalent binary code at its
output. Generally, digital encoders produce outputs of 2-bit, 3-bit or 4-bit codes depending
upon the number of data input lines. An "n-bit" binary encoder has 2n input lines and n-bit
output lines with common types that include 4-to-2, 8-to-3 and 16-to-4 line configurations.
The output lines of a digital encoder generate the binary equivalent of the input line whose
value is equal to "1" and are available to encode either a decimal or hexadecimal input pattern
to typically a binary or B.C.D. output code.
Sunday, June 22, 2014
Simplification of boolean expressions
Simplification
1. Simplify the Boolean expression
XY′Z′+XY′Z′W+XZ′
The above expression can be written as
XY′Z′ (1+W) +XZ′
=XY′Z′+XZ′ as 1+W=1
=XZ′ (Y′+1)
=XZ′ as Y′+1=1
2. Simplify the Boolean expression
X+X′Y+Y′+(X+Y′) X′Y
The above expression can be written as
X+X′Y+Y′+XX′Y+Y′X′Y
=X+X′Y+Y′ as XX′=0, and YY′=0
=X+Y+Y′ as X+X′Y=X+Y
=X+1 as Y+Y′=1
=1 as X + 1=1
3. Simplify the Boolean expression
Z(Y+Z) (X+Y+Z)
the above expression can be written as
(ZY+ZZ)(X+Y+Z)
= (ZY+Z) (X+Y+Z) as ZZ=Z
=Z(X+Y+Z) as Z+ZY=Z
=ZX+ZY+ZZ
=ZX+ZY+Z as ZZ=Z,
=ZX+Z as Z+ZY=Z
=Z as Z+ZX=Z
4. Simplify the Boolean expression
(X+Y)(X′+Z)(Y+Z)
The above expression can be written as
(XX′+XZ+YX′+YZ)(Y+Z)
=(XZ+YX′+YZ) (Y+Z) as XX′=0
=XZY+YYX′+YYZ+XZZ+YX′Z+YZZ
=XZY+YX′+YZ+XZ+YX′Z+YZ as YY=Y, ZZ=Z
Rearranging the terms we get
XZY+XZ+YX′+YX′Z+YZ as YZ+YZ=YZ
=XZ(Y+1) +YX′+YZ (X′+1) as Y+1=1, X′+1=1
=XZ+YX′+YZ
Now it seems that it cannot be reduced further. But apply the following trick:
The above expression can be written as
XZ+YX′+YZ(X+X′) as X+X′=1
=XZ+YX′+YZX+YZX′
Rearranging the terms we get
XZ+YXZ+Y X′+YX′Z
=XZ (1+Y) +YX′ (1+Z)
=XZ+YX′ as 1+Y=1, 1+Z=1
1. Simplify the Boolean expression
XY′Z′+XY′Z′W+XZ′
The above expression can be written as
XY′Z′ (1+W) +XZ′
=XY′Z′+XZ′ as 1+W=1
=XZ′ (Y′+1)
=XZ′ as Y′+1=1
2. Simplify the Boolean expression
X+X′Y+Y′+(X+Y′) X′Y
The above expression can be written as
X+X′Y+Y′+XX′Y+Y′X′Y
=X+X′Y+Y′ as XX′=0, and YY′=0
=X+Y+Y′ as X+X′Y=X+Y
=X+1 as Y+Y′=1
=1 as X + 1=1
3. Simplify the Boolean expression
Z(Y+Z) (X+Y+Z)
the above expression can be written as
(ZY+ZZ)(X+Y+Z)
= (ZY+Z) (X+Y+Z) as ZZ=Z
=Z(X+Y+Z) as Z+ZY=Z
=ZX+ZY+ZZ
=ZX+ZY+Z as ZZ=Z,
=ZX+Z as Z+ZY=Z
=Z as Z+ZX=Z
4. Simplify the Boolean expression
(X+Y)(X′+Z)(Y+Z)
The above expression can be written as
(XX′+XZ+YX′+YZ)(Y+Z)
=(XZ+YX′+YZ) (Y+Z) as XX′=0
=XZY+YYX′+YYZ+XZZ+YX′Z+YZZ
=XZY+YX′+YZ+XZ+YX′Z+YZ as YY=Y, ZZ=Z
Rearranging the terms we get
XZY+XZ+YX′+YX′Z+YZ as YZ+YZ=YZ
=XZ(Y+1) +YX′+YZ (X′+1) as Y+1=1, X′+1=1
=XZ+YX′+YZ
Now it seems that it cannot be reduced further. But apply the following trick:
The above expression can be written as
XZ+YX′+YZ(X+X′) as X+X′=1
=XZ+YX′+YZX+YZX′
Rearranging the terms we get
XZ+YXZ+Y X′+YX′Z
=XZ (1+Y) +YX′ (1+Z)
=XZ+YX′ as 1+Y=1, 1+Z=1
Saturday, June 21, 2014
Boolean Algebra and logic gates
INTRODUCTION The process of converting control objectives into a ladder logic program requires structured thought. Boolean algebra provides the tools needed to analyze and design these systems.
BOOLEAN ALGEBRA The techniques can model a logical system with a single equation. The equation can then be simplified and/or manipulated into new forms. The same techniques developed for circuit designers adapt very well to ladder logic programming. Boolean equations consist of variables and operations and look very similar to normal algebraic equations. The three basic operators are AND, OR and NOT; more complex operators include exclusive or (EOR), not and (NAND), not or (NOR). Small truth tables for these function. Each operator is shown in a simple equation with the variables A and B being used to calculate a value for X. Truth tables are a simple (but bulky) method for showing all of the possible combinations that will turn an output on or off.
Gates with truth tables
BOOLEAN ALGEBRA The techniques can model a logical system with a single equation. The equation can then be simplified and/or manipulated into new forms. The same techniques developed for circuit designers adapt very well to ladder logic programming. Boolean equations consist of variables and operations and look very similar to normal algebraic equations. The three basic operators are AND, OR and NOT; more complex operators include exclusive or (EOR), not and (NAND), not or (NOR). Small truth tables for these function. Each operator is shown in a simple equation with the variables A and B being used to calculate a value for X. Truth tables are a simple (but bulky) method for showing all of the possible combinations that will turn an output on or off.
Gates with truth tables
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| Truth table with logic gates |
Functional units of computer system,control unit and arithmetic logic section
FUNCTIONAL UNITS OF A COMPUTER SYSTEM Digital computer systems consist of three distinct units. These units are as follows: Input unit Central Processing unit Output unit these units are interconnected by electrical cables to permit communication between them. This allows the computer to function as a system. Input Unit A computer must receive both data and program statements to function properly and be able to solve problems. The method of feeding data and programs to a computer is accomplished by an input device. Computer input devices read data from a source, such as magnetic disks, and translate that data into electronic impulses for transfer into the CPU. Some typical input devices are a keyboard, a mouse, or a scanner. Central Processing Unit The brain of a computer system is the central processing unit (CPU). The CPU processes data transferred to it from one of the various input devices. It then transfers either an intermediate or final result of the CPU to one or more output devices.
CONTROL SECTION The control section directs the flow of traffic (operations) and data. It also maintains order within the computer. The control section selects one program statement at a time from the program storage area, interprets the statement, and sends the appropriate electronic impulses to the arithmetic-logic and storage sections so they can carry out the instructions.
ARITHMETIC-LOGIC SECTION The arithmetic-logic section performs arithmetic operations, such as addition, subtraction, multiplication, and division. Through internal logic capability, it tests
CONTROL SECTION The control section directs the flow of traffic (operations) and data. It also maintains order within the computer. The control section selects one program statement at a time from the program storage area, interprets the statement, and sends the appropriate electronic impulses to the arithmetic-logic and storage sections so they can carry out the instructions.
ARITHMETIC-LOGIC SECTION The arithmetic-logic section performs arithmetic operations, such as addition, subtraction, multiplication, and division. Through internal logic capability, it tests
Friday, June 20, 2014
Introduction to Computer Organization & Architecture:
Computer architecture refers to those attributes of a system visible to a programmeror we can say those attributes that have a direct impact on the logical execution of a program.
Computer organization refers to the operational units and their interconnection that realize the architecture specification.
A system consist of set of objects or components such as monitor,keyboard,cpu and softwares as well.
so designer analys it as structure and function
Structure it is the arrangement of components
Function it is the operation of each component as a part of structure
Computer organization refers to the operational units and their interconnection that realize the architecture specification.
A system consist of set of objects or components such as monitor,keyboard,cpu and softwares as well.
so designer analys it as structure and function
Structure it is the arrangement of components
Function it is the operation of each component as a part of structure
Thursday, June 19, 2014
Database management system (DBMS)
Database:- It is collection of data.
Database management system (DBMS):-It is the software that interact between the user,application and data itself.
Database management system (DBMS):-It is the software that interact between the user,application and data itself.
Computer system architecture defination
COMPUTER ARCHITECTURE:-
Computer architecture is a detail how a set of software and hardware technology standards interact to form a computer system.
Computer architecture is a detail how a set of software and hardware technology standards interact to form a computer system.
Computer system architecture (CSA) Syllabus
- Introduction to Computer Organization & Architecture:
- Evolution of Computers from 1st Generation to Pentium and
- Power PC
- Von Neumann machine Flynn's Classification - SISD, SIMD, MISD,
- MIMD
- Basic Computer Organization:
- Computer Registers, Instruction Codes, Computer Instructions
- Timing and Control, Instruction Cycle
- Memory Reference Instructions
- Input-Output and Interrupt
- Complete Computer Description
- Basic Computer Organization taking 8085 as an example
- binary arithmetic - add, subtract, multiply - algorithms and
- Microprogrammed Control: Control Memory, Address Sequencing,
- Micro program Example
- Design of Control unit:
- Central Processing Unit introduction
- General Register Organization
- Stack Organization. Instruction Format ( Three address, Two
- Address, One address, Zero address),
- Program Control:
- Status bits, Conditional Branch Instructions, Program Interrupts
- & Types
- Addressing Modes, Data Transfer and Manipulation
- Program control, RISC/CISC Characteristics
- Pipelining and Instruction cycle:
- Parallel processing, Pipelining, Arithmetic pipelining
- Input-Output Organization:
- Peripheral Devices, I/O Interface Asynchronous Data Transfer,
- Modes of Transfer
- Direct Memory Access(DMA),DMA Transfer, DMA Controller
- Input-Output Processor(IOP), CPU-IOP Communication
- Memory Organization:
- Memory Hierarchy Main Memory(RAM & ROM Chips), Auxiliary
- Memory(Magnetic Disc & Tapes) Associative Memory Cache
- Memory(Associative Mapping,
- Direct Mapping, Set-Associative Mapping), Virtual Memory
Wednesday, June 18, 2014
Syllabus for data structure
- Introduction: Basic Terminology, Elementary Data Organization,
- Data Structures and Operations, Algorithm : Complexity, Time-Space Tradeoff, Asymptotic Notations for Complexity( Ω ,θ, O),
- Array: Introduction, Representation of Linear Arrays in Memory, Traversing Linear Arrays, Arrays: Inserting and Deleting (at Beginning, middle and at the end)
- Searching: Linear and Binary Search with their Complexity
- Sorting: Bubble Sort & its Complexity,
- Linked List: Introduction & its memory representation, Traversing a Linked List,
- Insertion into Linked List (sorted and unsorted Linked List)
- Deleting from Linked List,
- Operations on Doubly Linked List,
- Circular linked List & its applications,
- Stacks & Queues: Array and Linked representation of Stacks,
- Implementations of recursive and non recursive procedures by Stacks,
- Applications: Arithmetic Expressions
- Polish Notation: Evaluation of Arithmetic Expressions
- Transforming Infix Expressions into Postfix Expressions
- Queues : Representation as Array and Linked List, Deques, Priority Queues
- Sorting Techniques-Quick sort , Merge Sort , Radix Sort, Selection Sort, Insertion Sort & their complexity,
- Trees: Binary trees, complete binary trees,
- Binary Search Trees, Data structures for representing binary trees.
- Insertion, deletion and searching in these trees.
- Tree Traversal: preorder, In order, Post order and their algorithms,
- Balanced binary Trees, AVL trees,
- insertion and Deletion in AVL tree, Heaps
- Difference between heap and Array, insertion and deletion in heap.
- Heap sort and its applications,
- Graphs: Basic terminology, directed and undirected graphs, notion of path.
- Representation of graphs: edge list structures, adjacency list structures, adjacency matrix.
- Linked List representation of Graph, Operations on Graph
- Graph traversals: DFS, BFS,
- Hashing: Techniques, Collision and its resolving.
Tuesday, June 17, 2014
Data Structure
Data structure is a way to organise data in memory.
There are five types of data structures:-
1.Array
2.Linked list
3.Queue
4.Stack
5.Trees and Graphs