WHAT IS THE INTERNET

Internet is a system of computer networks that are spread all over the word the world and use a number of protocol to communicate withe one another such as
Transmission Control Protocol (TCP) and Internet Protocol (IP). Internet is still uncharted and there is no central authority controlling the content of the internet and user connectivity. Any computer with a modem
(a computer interface to standard telephone lines) can be connected to the Internet. Following are two common of Internet connection:

Dial-UP Connections 

Individual subscribers in order to access the internet make use of dial-up connections.

To access the Internet through a dial-up connection you need a personal computer, a modem and an appropriate communication software like the Internet Explorer. In this mode, there is a host which services the client requests for the information . The host is called using a local or toll-free number. 

There are a number of dial-up connection providers is the market, so the user can decide which one to choose depending upon their needs and the services offered by he connection providers.

Direct Connection

Direct connection are those use wireless medium for information transfer. Commonly direct connection

are available to institutions, which lease high-speed connection to regional networks and service providers, An Internet connection using phone lines and modems dose not give users a speedy access to the internet . An Internet connection using ordinary telephone lines has a data transfer rate using a direct connection is of the order of mega characters per second.

Read more ...

BASIC CONCEPT OF MEMORY

A computer use tow types of storage : man memory memory and secondary memory. The main memory temporarily stores the instructions to be executed by the computer. The CPU of a computer retrieves instructions from main memory for execution.On the
other hand, secondary memory is constituted of various secondary storage devices such as magnetic disks and magnetic tapes, which stores the information permanently in the form of files.
Main memory, RAM. is the temporary read/write memory of a computer and fasted the secondary storages
devices. Main memory is a set of location defined by sequentially numbered addresses for storing programs for execution, and each location contains a binary number. You can access each byte of RAM directly without reading the previous bytes sequentially.
Each byte in a RAM has an addresses . The addresses are mostly sequential hexadecimal numbers. Usually ,
the addresses of RAM start from 00000.
The memory address that is referred to an instruction can be mentioned in two ways.
 When the exact location of a byte in RAM is mentioned, the addressing scheme is called absolute addressing . The address itself is called on absolute address. For example , the address 5508 indicates a specific location in the RAM, and 5508 is the absolute address of the location.

Similarly , a counter can also be used for location an address. For example, the starting address of a program in memory is 54EE. This address is the root or base address. All the addresses  in this program are relative to the address 54EE such as 8 bytes from the address 54EE The instruction in the program is add the content of the address 3 to the content at address 4. The address, 3 and 4 here are relative and refer to the third and fourth location in the main memory  starting form the root address 54EE. This is called relative addressing and the address itself is called relative address.

Read more ...

WINDOWS NT SERVER ARCHITECTURE

Windows NT Server contain various components among which some of the components run in user mode and other run in kernel mode. Kernel Mode is a
special type of mode in which all the hardware and system data can be accessed by  the running code,
whereas in user mode, there in only restricted access to the system data and hardware by the running code. The user mode is also referred to as non-privileged mode. The architecture of Windows NT Server contains the following components :

• Hardware Abstraction Layer (HAL)
• Kernel
• NT Executive
• Protected Environment Subsystems

Hardware Abstraction Layer (HAL)

HAL is a software interface located between the hardware and the operating system and it is the lowest level

component of the Windows NT operating system. HAL is platform-specific and carries cods for communication and controlling the hardware on which Windows NT operates. HAL gives the interface for

Symmetric MultiProcessing (SMP) and enable Windows NT Server more application-friendly.

HAL is executed as a Dynamic Link Library (DLL) and, is responsible for protecting Windows NT server based on HAL is that it is not compatible with the older version of DOS and Windows program : 

Read more ...

CLASSIFICATION OF OPERATING SYSTEMS

All operating systems consist of  similar components and perform  almost similar functions but the methods and procedures for performing these functions are different. Operating systems are classified into following different categories based on their distinguishing features: 

• Single -user Operating system
• Multi-user Operating system
• Batch processing Operating system
• Multiprogramming Operating system
• Multitasking Operating system 
• Parallel Operating system
• Distributed Operating system
• Real.time operating system

Single-User Operating System 

It allows a single user to access a computer at a time . These computer have single processor and execute 

single program . The resources such as CPU and I/O device are constantly available to the user in a single 

user operating system for operating the system. As a result, the CPU site idle for most of the time and is not utilised to it maximum. A single -user OS is divided into categories :

• Single-user, single-tasking operating system
• single-user , multi-tasking operating system

The single-user, single-tasking operating system allows a single-user to execute on

program at a time. MS-DOS and palm OS for palm hand-held computer at

examples of single-user single-tasking operating system .

Single-user multitasking operating system allows a single-user to operate multiple programs at the same time. For example, you can perform calculation in Excel sheet print a Word document and download a file from the internet concurrently .

Mac OS Windows 95, Windows 98, Windows NT Workstation and Windows 2000 Professional, operating system for desktop and laptop computer are the examples of single-user, multi-tasking operating system. 

Read more ...

The Visual Basic Interface with video tutorial

Before we begin Visual Basic 6 programming, let us understand some basic concepts of programming. According to Webopedia, a computer program is an organized list of instructions that, when executed, causes the computer to behave in a predetermined manner. Without programs, computers are useless. Therefore, programming means designing or creating a set of instructions to ask the computer to carry out certain jobs which normally are very much faster than human beings can do.

A lot of people think that computer CPU is a very intelligent thing, which in actual fact it is a dumb and inanimate object that can do nothing without human assistance. The microchips of  a CPU can only understand two distinct electrical states, namely, the on and off states, or 0 and 1 codes in the binary system. So, the CPU only understands a combinations of 0 and 1 codes, a language which we called machine language. Machine language is extremely difficult to learn and it is not for us laymen to master it easily.  Fortunately , we have many smart programmers who wrote interpreters and compilers that can translate human language-like programs such as BASIC into machine language so that the computer can carry out the instructions entered by the users. Machine language  is known as the primitive language while Interpreters and compilers like Visual Basic are called high-level language. Some of the high level computer languages beside Visual Basic are  Fortran, Cobol, Java, C, C++, Turbo Pascal, and etc .  

Read more ...

Visual Basic Programming An Introduction

Why Visual Basic?

• H Programming for the Windows User
• 
  
• Interface is extremely complicated.
• 
  
• H Other Graphical User Interfaces (GUI) areno better.

• H Visual Basic provides a convenient methodfor building user interfaces.

• H Visual Basic can interface with code written

in C, for efficiency.

What Visual Basic is not

H Visual Basic is not, a powerful

programming language that enables you to

do anything you want.

H Visual Basic is not, elegant or fast.

H Visual Basic is not, a replacement for C.

H Visual Basic is not, anything like any other

programming language you have ever used.

When You Program in VB:

H You draw pictures of your user interface.

H You draw buttons, text boxes, and other

user-interface items.

H You add little snippets of code to handle the

user interaction.

H You add initialization code, usually as the

last step.

H If you like, you can code more complex

functions. (But many do not.)

Read more ...

Object-Oriented Design & Programming

Object-Oriented Design and Programming

C++ Basic Examples

Bounded Stack Example

Linked List Stack Example

UNIX File ADT Example

Speci cation for a String ADT

String Class ADT Example

Circular Queue Class Example

Matrix Class Example, 

Bounded Stack Example

The following program implements a bounded

stack abstraction

{ This is the solution to the rst programming

assignment

e.g.,

/* The stack consists of ELEMENT TYPEs. */

typedef int ELEMENT TYPE;

class Stack f

private:

/* Bottom and maximum size of the stack. */

enum fBOTTOM = 0, SIZE = 100g;

/* Keeps track of the current top of stack. */

int stack top;

/* Holds the stack's contents. */

ELEMENT TYPE stack[SIZE];

2

Bounded Stack Example (cont'd)

/* The public section. */

public:

/* Initialize a new stack so that it is empty. */

Stack (void);

/* Copy constructor */

Stack (const Stack &s);

/* Assignment operator */

Stack &operator= (const Stack &s);

/* Perform actions when stack is destroyed. */

~Stack (void);

/* Place a new item on top of the stack

Does not check if the stack is full. */

void push (ELEMENT TYPE new item);

/* Remove and return the top stack item

Does not check if stack is empty. */

ELEMENT TYPE pop (void);

/* Return top stack item without removing it

Does not check if stack is empty. */

ELEMENT TYPE top (void);

/* Returns 1 if the stack is empty,

otherwise returns 0. */

int is empty (void);

/* Returns 1 if stack full, else returns 0. */

int is full (void);

g;

String Class ADT Example

/* Check whether String S is a substring

in this String. Return ??1 if it is not, oth-

erwise return the index position where the

substring begins. */

int String:: nd (const String &s) const f

char rstc = s[0]; // s.operator[] (0);

int end index = this->len ?? s.len + 1;

for (int i = 0;

i < end index

&& ((*this)[i] != rstc jj

memcmp (&this->str[i] + 1, s.str + 1, s.len ?? 1) !

i++)

;

return i < end index ? i : ??1;

g

/* Extract a substring from this String of

size count starting at index pos. */

String String::substr (int index pos, int count) const f

if (index pos < 0 jj index pos + count > this->len)

return "";

else f

String tmp (count);

for (int i = 0; i < count; i++)

tmp[i] = (*this)[index pos++];

/* tmp.operator[] (i) =

this->operator[] (index pos++); */

return tmp;

g

g

Read more ...