Complete Computer Knowledge Portal

Monday, December 16, 2013

Difference Between CDMA and GSM

Acronym for
Code Division Multiple Access and also known as IS-95 or CDMAone.
Global System for Mobile Communication.
Technology Used
This Technology is based on spread spectrum technology and does not require dividing the channel by time. It also allows several users to share same frequency in a given band or space. Users are isolated by bipolar sequences and can share same frequency.
In this technology Carrier is divided into number of time slots. These different time slots are assigned to each user and until ongoing call is not finished, no other user can access this assigned slot.

Difference Between TDMA and FDMA

Acronym for
Time Division Multiple Access
Frequency Division Multiple Access
In TDMA radio spectrum is divided into time slots and in each slot only one user is allowed to either send or receive.
In FDMA individual channels are assigned to individual users. Each user is allocated a unique frequency or band.
Bandwidth Sharing
In TDMA single frequency is shared by several users.
Frequency sharing is not allowed. If FDMA channel is not in use, it can’t be utilized by other user to increase or share capacity.

Difference Between 8 bit ISA, 16 bit ISA and EISA

ISA( 8 Bit)
ISA (16 Bit)
Acronym for
Industry Standard Architecture
Industry Standard Architecture
Enhanced Industry Standard Architecture
Introduced In
Group of Nine Computer manufacturing Companies Led by Compaq(AST Research, Compaq Computer, Epson, Hewlett-Packard, NEC, Olivetti, Tandy, WYSE, Zenith Data Systems)

Difference Between Single Mode and Multi Mode Fiber

Single Mode Fiber
Multi-Mode Fiber
Core Size
It has very small sized core and allows only one mode of light to propagate.
It has large Sized core and allows multiple mode of light to propagate.
1310+ nm lasers 1 and 10 Gb/s
1 Gb/s + w/ DWDM
High precision packaging
850 nm and 1310 nm LEDs
850 nm lasers at 1 & 10 Gb/s
Low precision packaging
Distance Support
This Cable is used to transmit data to long distances. Because as the light passes through the core, the number of light reflections created decreases which decreases attenuation and creates the ability for the signal to travel faster forward. Up to 60 KMs +
This cable is used to transmit data to short distances. Because as the number of lights passes through the core, high dispersion and attenuation reduces the quality of the signal. Up to 2 KMs

Monday, December 9, 2013

Retrieving Data from MYSQL Database using PHP

Using these easy steps you can easily retrieve the data from MYSQL database. In this example I am assuming that you have already created MYSQL database and already contains some tabular data.
Create database named mydb

Create Table student on mydb Database:
Table info is created with three fields: id, name and Email Address. Id will be automatically incremented after every insert operation.
CREATE TABLE `mydb`.`student` (
`name` VARCHAR( 100 ) NOT NULL ,
`contact_no` int( 20 ) NOT NULL ,
PRIMARY KEY ( `id` )

Insert some raw data for Accessing
INSERT INTO `mydb`.`student` (`id`, `name`, `contact_no`) VALUES (NULL, 'Dashmesh', '123456');

How to insert PHP Form data into MYSQL Database?

Here are some easy steps that are used to insert PHP data into MYSQL database
      1) Create MYSQL database
           2) Create index.php or index.html page with required inputs.
           3) PHP script to insert data.
           4) Database connection
Create the database testing
Create Table info on testing Database:
Table info is created with three fields: id, name and Email Address. Id will be automatically incremented after every insert operation.
CREATE TABLE `testing`.`info` (
`name` VARCHAR( 100 ) NOT NULL ,
`email` VARCHAR( 100 ) NOT NULL ,
PRIMARY KEY ( `id` )

Saturday, September 7, 2013

SCSI (Small Computer System Interface)

SCSI (Pronounced as Skuzzy) is an Acronym for Small Computer System Interface. It is a set of standards for connecting and transferring data between Computer and Peripheral devices. It was developed by Shugart Associates Company in 1981 as a universal and intelligent disk drive interface.
This Interface is generally used for connecting Hard Disk Drives and Tape Drives but can also be used to connect wide range of other devices. This Interface is derived from Shugart Associates System Interface (SASI pronounced as sassy). SASI Controller works as bridge between Disk Drive’s Low level interface and Host Computer. Larry Boucher is considered to be the father of SASI and SCSI. Up to February 1982, ANSI developed this specification as SASI and “Shugart Associates System Interface”. Committee documenting this Standard did not allow it to be named after a company name and after a full day discussion named as SCSI (Small Computer System Interface).

Wednesday, August 14, 2013

How to Test Power Supply (SMPS)?

Power Supply is the most important part of your computer System because you can not work until your computer is not powering on.  Here I am describing some techniques that you can use to troubleshoot and overcome the SMPS Problems.

Functions Performed

Following Functions are provided by the SMPS (Switch Mode Power Supply):
Its main function is to provide required DC voltage to operate all components in the system.
Different Voltage levels obtained from same power supply.
Output is not affected by the input means if input voltage is between 120V AC to 240V AC the output obtained will be constant. It also provides electrical protection to all components from under voltage or over voltage.
It Provides Necessary Cooling to its components and protects computer from overheating. 

Wednesday, August 7, 2013

8 Bit Industry Standard Architecture(ISA) or PC Bus

ISA (Industry Standard Architecture) was first used with the IBM PC in 1981. It was the first open system for PC architecture. No restriction was put on the use of this interconnection method by the IBM. IBM offered free licensing of this PC architecture technique which resulted in more popularity of this. Some main features of 8 bit ISA are:
1) It was introduced by IBM and was the first open system for PC architecture.
2) It provides data transfer rate up to 4.77 Mbps.
3) ISA interface contains 62 pins to interface add on cards. These 62 pins are arranged in two rows, each containing 31 pins.
4) Distance between each pin is 0.1 Inches.
5) 8 Bit ISA make use of Following signals:
    3 Ground Signals
    2 +5V DC Supply
   +12,12,-5V DC supply
    Bidirectional 8 bit data Bus.
   20 Address line, hence memory address space of 1MB (220=1MB)
   3 DMA request lines
   3 DMA acknowledge lines.
   Six Interrupt Support

Wednesday, July 24, 2013

Functions of North Bridge

After CPU North Bridge is the core chipset on the computer motherboard that controls data communication between CPU and Motherboard. It runs at full processor speed. It mainly works as Memory controller and System Controller. It incorporates interface between Processor and rest of motherboard components.
Chipset is actually numbered according to the number of North Bridge. Nvidia GeForce 320M is a Northbridge /Southbridge fabrication in a single chip. Following are some major functions that are performed by the North Bridge:
Processor Support: Chipset is the major decider on the motherboard that decides which processor is supported, of what speed and how many processors are supported? Following areas are covered by North Bridge under this:
CPU Interface Socket Type: North Bridge is interfaced with the processor through host processor bus and CPU socket. No. of processor sockets are available in the market for this purpose such as Socket 7,Socket -1, Socket A etc. This socket number is decider that which particular Processor class is supported on that motherboard.

Functions of South Bridge

South Bridge is a chipset that is used for controlling I/O Functions such as USB, disk interfaces, PCI Bus, Super I/O Chip support etc. In other words it works as peripheral controller. The main feature of Southbridge is that same South Bridge can be used with different types of North bridges. It is generally located at the lower edge of the motherboard.
Following are some Major Functions Performed by South Bridge:
I/O Control: South Bridge is the key point that decides which kinds of buses, at what speed, and which features will be supported by the system. South bridge controls PCI and ISA buses and transfers information to them or from them.

USB Ports Control: USB Support on the motherboard is provided by the south bridge and which is the main interface for mostly peripheral devices.

SPX (Sequential Packet Exchange) Protocols

It is the version of Novels’ Sequenced Packet Protocol (SPP). It is a transport layer protocol and is used by client server applications. This protocol provides a packet delivery system for third party applications.
Figure given below illustrate the structure of SPX packet.

Connection Control Flag
DataStream Type
Source Connection ID
Destination Connection ID
Sequence Number
Acknowledge Number
Allocation Number
0-534 bytes of data

Monday, July 22, 2013

How to Download YouTube Videos?

Hello friend today I am going to tell you very special software with the help of which you can download videos from any site like YouTube. Actually this is a plugin that comes with our beloved Mozilla Firefox web browser. So the primary platform to install this plugin is Mozilla Firefox. Here are some important points about this plugin:
Plugin Name is Video Download Helper. It is a tool for web content extraction and can download videos and pictures from other sites.
It’s absolutely free and can be downloaded from official website of Mozilla (Click Here to Download)
No need to install any video downloader.
No Download Limit.
Fast Download Speed.

Saturday, July 20, 2013

Intel 8255 (Programmable Peripheral Interface)

Intel 8255 is a PPI (Programmable Peripheral Interface) and is used to interface Peripheral devices to microcomputers. It can be programmed in a variety of ways as per Programmer Requirements. It has two versions 8255A and 8255B. Both of them are similar in general description but are different in their electrical characteristics.
Intel 8255 Consists of Three 8 Bit Ports: Port A, Port B and Port C. The Port C is further divided into two 4 Bit Ports: Port CUPPER and CLOWER. These three ports are divided into two groups for the purpose of Programming:
Group A: This Includes Port A (PA0-PA7) and 4 MSBs of Port C (PC4-PC7).
Group B: This Includes Port B (PB0-PB7) and 4 LSBs of Port C (PC0-PC3).

Wednesday, July 17, 2013

User Defined Data Types in C++

The third type of data type in C++ is user defined. Following are some user defined data types:
Structure:  Collection of data elements grouped under one name is called Structure. Different data elements are called members and can have different data type of different length.
Struct Student
Int roll_no;
Float marks;
In this example Student is declared as Structure with members roll_no and marks. BA, BSC, BCOM are the objects of structure Student. Here roll_no is declared as integer and marks as float, which are fundamental data types.

Tuesday, July 16, 2013


Operating a Chip at higher clock speed than its rated clock speed is called Overclocking. CPU Clock speed is the product of FSB (Front Side Bus) Clock and clock multiplier. Overclocking is achieved by either increasing FSB Clock or Clock multiplier or either by increasing both.

Need of Overclocking
The idea behind the use of Overclocking concept is to increase the system performance at no cost or very little cost. We can Overclock a processor by just changing some settings on motherboard or in CMOS setup. The main considerable point in Overclocking is heat. Processor can only be overclocked if and only if proper cooling is there. E.g. Pentium 4 @2.0 GHz Processor can be overclocked to gain 2.2 GHz Clock speed.

Difference Between Online and Offline UPS

Online UPS
Offline UPS
Inverter always remains ON all the time and provides output Power.
Inverter is switched on only is main supply is off.
Switching Time
Online UPS has switching time between 0-1 ms
Switching Time is generally <5 ms.
Area of Use
Generally used in large organizations and the areas where perfect UPS supply is needed.
Generally used for personal use at homes or small offices.

Tuesday, July 9, 2013

Derived Data Type in C++

The Data type that is derived from fundamental data types is called derived data type. Some of them are explained below:

 Array:  An array is a collection of homogeneous type of data. It is a named list of finite numbers of data elements. In array each data element is referenced by a set of consecutive numbers i.e. 1, 2, 3……n. If TECH is an array of five elements than its elements will be referenced as: TECH [1], TECH [2], TECH [3], TECH [4], TECH[5]. An Array can either be one dimensional, two dimensional or multidimensional.

Thursday, July 4, 2013

Fundamental Data Types in C++

These are those data types that are not composed of any other data types. C++ makes use of following five fundamental data types

1) Char
: This data type is used to store basic character sets. It is sometimes referred to as integer type because letters and symbols are represented in memory by the associated number codes. Table given below illustrates various types of character types along with their range.

Character Type
Size in Bytes
Minimal Range
-128 to 127
Unsigned Char
0 to 255
Signed Char
-128 to 127