Binary Data Representation

A binary number may also have a binary point, in addition to the sign. The binary point is used for representing fractions, integers and integer-fraction numbers. Registers are high-speed storage areas within the Central Processing Unit (CPU) of the computer. All data is brought into a register before it can be processed. For example, if two numbers are to be added, both the numbers are brought in registers, added, and the result is also placed in a register. There are two ways of representing the position of the binary point in the register - fixed point number representation and floating point number representation.

The fixed point number representation assumes that the binary point is fixed at one position. The binary point is not actually present in the register, but its presence is assumed based on whether the number which is stored is a fraction or an integer.

The floating point number representation uses two registers. The first register stores the number without the binary point. The second register stores a number that indicates the position of the binary point in the first register.

We shall now discuss representation of data in the fixed point number representation and floating point number representation.

4.1. Fixed Point Number Representation

The integer binary signed number is represented as follows –

• For a positive integer binary number, the sign bit is 0 and the magnitude is a positive binary number.
• For a negative integer binary number, the sign bit is 1. The magnitude is represented in any one of the three ways-
• Signed Magnitude representation - The magnitude is the positive binary number itself.
• Signed 1’s complement representation - The magnitude is the 1’s complement of the positive binary number.
• Signed 2’s complement representation - The magnitude is the 2’s complement of the positive binary number.

 the representation of the signed number 18.

Signed magnitude and signed 1’s complement representation are seldom used in computer arithmetic. Let’s now perform arithmetic operations on the signed binary numbers. We use the signed 2’s complement representation to represent the negative numbers.

Addition of signed binary numbers – The addition of any two signed binary numbers is performed as follows -

• Represent the positive number in binary form.(For e.g., +5 is 0000 0101 and +10 is 0000 1010)
• Represent the negative number in 2’s complement form. (For e.g., -5 is 1111 1011 and -10 is 1111 0110)
• Add the bits of the two signed binary numbers.
• Ignore any carry out from the sign bit position.
Please note that the negative output is automatically in the 2’s complement form. We get the decimal equivalent of the negative output number, by finding its 2’s complement, and attaching a negative sign to the obtained result. Let’s understand the addition of two signed binary numbers with the help of some examples. Example 1. Add +5 and +10. We represent +5 in binary form, i.e., 0000 0101. We represent +10 in binary form, i.e., 0000 1010. Add the two numbers. The result is 0000 1111 i.e. +15.
Example 2. Add -5 and +10. We represent -5 in 2’s complement form, i.e., 1111 1011. We represent +10 in binary form, i.e., 0000 1010. Add the two numbers. The result is 0000 0101 i.e. +5. Example 3. Add +5 and -10. We represent +5 in binary form, i.e., 0000 0101. We represent -10 in 2’s complement form, i.e., 1111 0110. Add the two numbers. The result is 1111 1011. The result is in 2’s complement form. To find the decimal equivalent of the result 1111 1011 – Find the 2’s complement of 1111 1011, i.e., 0000 0100 + 1 = 0000 0101. This is binary equivalent of +5. Attaching a negative sign to the obtained result gives us -5.
Example 4. Add -5 and -10.
We represent -5 in 2’s complement form, i.e., 1111 1011. We represent -10 in 2’s complement form, i.e., 1111 0110. Add the two numbers. The result is 1111 0001. The result is in 2’s complement form.
To find the decimal equivalent of the result 1111 0001- Find the 2’s complement of 1111 0001, i.e., 0000 1110 + 1 = 0000 1111. This is binary equivalent of +15. Attaching a negative sign to the obtained result gives us -15.

Subtraction of signed binary numbers – The subtraction of signed binary numbers is changed to the addition of two signed numbers. For this, the sign of the second number is changed before performing the addition operation.

(-A) – (+B) = (-A) + (-B) (+B in subtraction is changed to –B in addition)

(+A) – (+B) = (+A) + (-B) (+B in subtraction is changed to –B in addition)

(-A) – (-B) = (-A) + (+B) (-B in subtraction is changed to +B in addition)

(+A) – (-B) = (+A) + (+B) (-B in subtraction is changed to +B in addition)

We see that the subtraction of signed binary numbers is performed using the addition operation.

Signed and Unsigned Numbers

A binary number may be positive or negative. Generally, we use the symbol “+” and “-” to represent positive and negative numbers, respectively. The sign of a binary number has to be represented using 0 and 1, in the computer. An n-bit signed binary number consists of two parts – sign bit and magnitude. The left most bit, also called the Most Significant Bit (MSB) is the sign bit. The remaining n-1 bits denote the magnitude of the number.

In signed binary numbers, the sign bit is 0 for a positive number and 1 for a negative number. For example, 01100011 is a positive number since its sign bit is 0, and, 11001011 is a negative number since its sign bit is 1. An 8-bit signed number can represent data in the range -128 to +127 (-2⁷ to +2⁷-1). The leftmost bit is the sign bit.

In an n-bit unsigned binary number, the magnitude of the number n is stored in n bits. An 8-bit unsigned number can represent data in the range 0 to 255 (2⁸= 256).

Complement of Binary Numbers

Complements are used in computer for the simplification of the subtraction operation. We now see, how to find the complement of a binary number. There are two types of complements for the binary number system – 1’s complement and 2’s complement.

• 1’s complement of Binary number is computed by changing the bits 1 to 0 and the bits 0 to 1. For example,
• 2’s complement of Binary number is computed by adding 1 to the 1’s complement of the binary number. For example,
• 1’s complement of 110 is 001
• 1’s complement of 1011 is 0100
• 1’s complement of 1101111 is 0010000
• 2’s complement of 110 is 001 + 1 = 010
• 2’s complement of 1011 is 0100 + 1 = 0101
• 2’s complement of 1101111 is 0010000 + 1 = 0010001

BINARY SYSTEM & ARITHMATIC

The binary number system  is used in the computer systems. The digits 0 and 1 are combined to get different binary numbers like 1001, 11000110 etc. In a binary number, a digit 0 or 1 is called a bit. For example, 1001 is a 4-bit binary number, and, 11000110 is an 8-bit binary number. All kinds of data, be it alphabets, numbers, symbols, sound data or video data, are represented as combination of bits i.e. 0’s and 1’s. Each character is a unique combination of bits. We shall now discuss how to perform basic arithmetic operations in the binary number system. 

 

2.1. Binary Addition

Binary addition involves adding of two or more binary numbers. The binary addition rules are used while performing the binary addition. Table 1 shows the binary addition rules.

Table 1. Binary Addition Rules for two inputs

Binary addition of three inputs, when all the inputs are 1, follows the rule shown in Table 2.

Table 2. Binary Addition Rules for three inputs

Addition of the binary numbers involves the following steps-

1. Start addition by adding the bits in unit column (the rightmost column). Use the rules of binary addition.
2. The result of adding bits of a column is a sum with or without a carry.
3. Write the sum in the result of that column.
4. If carry is present, the carry is carried-over to the addition of the next left column.
5. Repeat steps 2-4 for each column, i.e., the tens column, hundreds column and so on.

Let us now understand binary addition with the help of some examples.

Example 1. Add 10 and 01. Verify the answer with the help of decimal addition.

When we add 0 and 1 in the unit column, sum is 1 and there is no carry. The sum 1 is written in the unit column of the result. In the tens column, we add 1 and 0 to get the sum 1. There is no carry. The sum 1 is written in the tens column of the result.

Example 2. Add 01 and 11. Verify the answer with the help of decimal addition.

When we add 1 and 1 in the unit column, sum is 0 and carry is 1. The sum 0 is written in the unit column of the result. The carry is carried-over to the next column, i.e. the tens column. In the tens column, we add 0, 1 and the carried-over 1, to get sum 0 and carry 1. The sum 0 is written in the tens column of the result. The carry 1 is carried-over to the hundreds column. In the hundreds column, the result is 1.

Example 3. Add 11 and 11. Verify the answer with the help of decimal addition.

When we add 1 and 1 in the unit column, sum is 0 and carry is 1. The sum 0 is written in the unit column of the result. The carry is carried-over to the tens column. In the tens column, we add 1, 1 and the carried-over 1. We use the rule for binary addition of three inputs shown in Table 2. We get sum 1 and carry 1. The sum 1 is written in the tens column of the result. The carry 1 is carried-over to the hundreds column. In the hundreds column, the result is 1.

Example 4. Add 1101 and 1111. Verify the answer with the help of decimal addition.

Example 5. Add 10111, 11100 and 11. Verify the answer with the help of decimal addition.

TOLLFREE Nos 4 PC Problems

TOLL FREE Nos for any  PC Problems

AMD   18004256664

DELL  1800444026

HCL  18001808080

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Microsoft  1800111100

How to use Remote Desktop Connection (RDC)

If your home computer has Windows XP Pro (or Media Center Edition) installed, you can access it from any other computer running Windows from anywhere in the world using Remote Desktop Connection. Some versions of Windows

, like 98, Me, 2000 and require software available from Microsoft.com:
http://www.microsoft.com/windowsxp/downloads/tools/rdclientdl.mspx
There are a few steps required to configure your home network to accept connections from outside computers and additional security measures required to keep your PC safe from people who might be scanning for computers with RDC installed.

Set A Complex Password

Remote Desktop relies on Windows XP passwords for login. If you don't currently have a password configured for your account, or if your password is something simple, change it. At minimum, your password should be 10-12 characters long, with a combination of numbers, letters and special characters. This password is no longer just designed to keep out your roommate or family members, it's going to keep the entire Internet from accessing your computer.
Change the password for your Windows user account from the Users section of the Control Panel.

Enable Remote Desktop Connections

The first thing to do is enable Remote Desktop on the machine you want to connect to. Open System Properties either by right clicking the My Computer icon in the Start menu and choosing properties or Windows Key + Pause/Break on your keyboard. Click the Remote tab in System Properties and check the box next to Allow users to connect remotely to this computer.

You can verify RDC is working by connecting from any other computer on your local network.

Configure Your Router

If your router still has the factory default password, change it. While it's unlikely anyone will find your router on the Internet, not changing the password is asking to have it hacked. A strong password of 10-16 characters is advised.
The next step in the procedure is to configure your router to allow inbound connections to Remote Desktop on your local computer. This requires mapping a port on your router to a port on your local computer. The process for forwarding a port varies depending on who made your router, but in general there are a similar series of steps. Linksys refers to the port forwarding page as Applications & Gaming, most other routers refer to port forwarding options as Virtual Servers. To forward a router port your need to configure the following details:
Application or Description field: RDC
Port Range Start: 3389
Port Range End: 3389
Protocol Type: Both (or TCP if a both option isn't available)
IP Address of your PC: Type ipconfig at the command line if you don't know this
Enable: check a box to enable the port forward

For security reasons, if you don't travel often, disable this router port when you return from your trip.

Change the Remote Desktop Listening Port

For added security of your RDC setup, you can change the default port Remote Desktop Connection listens on from the host computer. This prevents detection by anyone doing a routine scan for RDC. This is also convenient if you want to connect to more than one RDC computer remotely. For instance, I have 3 computers that never leave home. By default, RDC watches the same port on all computers, which means I'll either get a conflict of some kind or I won't be able to connect at all. An alternative is to redirect RDC traffic to each computer.
You can read more about the process in Microsoft Knowledge Base article 306759
To change the listening port, you need to modify the Windows Registry. Locate the appropriate Registry key using Regedit.exe:
HKEY_LOCAL_MACHINE\System\CurrentControlSet\Control\TerminalServer\WinStations\RDP-Tcp\PortNumber
From the Edit menu, click Modify and then click Decimal. Choose a new port number. In general, choosing a number between 49152 and 65535 will avoid conflict with any other apps on your system, but you could theoretically use any port on the system. Once you set the port number you also need to configure your router to pass the specified port to your computer.
To access your computer remotely, instead of typing just the IP address, you need to type the IP address followed by the port number like this: 192.168.1.1:50001

Test Your Connection

The real trick is you need to leave home to test your configuration, so you don't really know it works until you are in the field. You need to know the IP address provided by your ISP to make the connection (Find your IP address). Visit a local coffee shop with WiFi to test the connection. Launch the Remote Desktop Connection client from Start > All Programs > Accessories > Communications.

Enter your home IP address and cross your fingers. If all went well, you'll see the Windows Login screen

Installing Remote Desktop connection on non-XP systemsInstalling Remote Desktop connection on non-XP systems

Non-Windows XP systems can also access Windows systems running Windows Remote Desktop. The local system used to access the remote computer must have the remote connectivity client software installed. To install the required Terminal Services components:

1. Insert a Windows XP Professional CD in the local system’s CD or DVD drive.
2. From the resulting Welcome To Microsoft Windows XP screen, click Perform Additional Tasks.
3. Click Setup Remote Desktop Connection from the What Do You Want To Do Screen.
4. The InstallShield Wizard will open; click Next on the Welcome To The InstallShield Wizard for Remote Desktop Connection.
5. Read and accept the license agreement and click Next.
6. Enter the customer name and organization, and specify whether the desktop connection is to be available to all users or only the logged in user and click Next.
7. Click Install.
8. Click Finish.

The older Windows system can now open the Remote Desktop Connection menu by clicking Start | Programs | Accessories | Communications | Remote Desktop Connection or by opening a command prompt and typing mstsc.

The Remote Desktop Connection

The Remote Desktop Connection software is pre-installed with Windows XP. To run it, click Start, click All Programs, click Accessories, click Communications, and then click Remote Desktop Connection. This software package can also be found on the Windows XP Professional and Windows XP Home Edition product CDs and can be installed on any supported Windows platform. To install from the CD, insert the disc into the target machine's CD-ROM drive, select Perform Additional Tasks, and then click Install Remote Desktop Connection.

Windows Remote Desktop

Connecting to a remote desktop is fairly straightforward, but a few elements must be in place first:

• The host desktop must have Internet access (preferably high-speed).
• The local system (the PC connecting to the remote desktop that will serve as the host) must be running Windows XP Professional (or a Windows 2003-flavor server) or have the appropriate Terminal Services tools installed.
• Firewalls between the local system and the remote host must be configured to pass the appropriate traffic.
• Remote Desktop must be installed and enabled on the target system.

Installing Remote Desktop

Remote Desktop is an optional Windows XP Professional service. To install it on a host system (to enable a computer to accept a remote connection request), Microsoft recommends you:

1. Click Start.
2. Click Control Panel.
3. Select Add Or Remove Programs.
4. Select Add/Remove Windows Components.
5. Select Internet Information Services.
6. Click the Details button.
7. Select World Wide Web Service.
8. Click the Details button.
9. Check the Remote Desktop Web Connection checkbox.
10. Click OK.
11. Click Next.
12. Click Finish to complete the wizard.
13. Click Start.
14. Select Run.
15. Enter Net Stop w3svc and click the OK button or press Enter.
16. Click Start.
17. Select All Programs.
18. Select Microsoft Update.
19. Select Scan For Updates.
20. Install all critical updates on the host system.
21. Click Start.
22. Select Run.
23. Enter Net Start w3svc and click the OK button.

Risk Management in IT

It is the method, by which the business managers control the overall operational and financial costs, on all their important business procedures which ultimately yield them profits.

Asset is an entity that demands security/safety. For e.g.

1. Information assets: e.g.

 Databases: about customers, personnel, production, sales, marketing, financial. These Information assets are critical for the business its confidentiality, integrity and availability is of utmost importance.
Data files: transaction data giving up to date information about each event.
Operation and support procedures: These have been developed over the years and provide detailed instructions on how to perform various activities.
Archived Information : Old Information that may be required to maintain by law.
 Continuity plans: These would be developed to overcome any disaster and maintain the continuity of business. Absence of these will lead to Ad-hoc decisions in crisis.


2. Software Assets:

 Application softwares.
 System Softwares.


3. Physical Assets:

 Computer Equipments
 Communication Equipments
 Storage Media
 Technical Equipments
 Furnitures and fixtures.

4. Services:

Computing services that the organization has outsourced.
Communication services like voice communication, data communication, value added services, wide area network. Environmental Conditioning services like heating, lighting, air conditioning and power.



Risk Assessment:

 A step in Risk Management Process
It is the determination of quantitative or qualitative value of risk related to a real situation and a well-known threat.
Quantitative risk assessment requires calculations of two components of risk:
R, the magnitude of the potential loss L, and the probability p that the loss will occur.

Bluetooth History

The name Bluetooth was derived from the Danish king Harald Blatand (Bluetooth), who is credited with uniting the people from Scandinavia during the tenth century. The Bluetooth SIG (Special Interest Group) was formed in February 1998. The original founding members of Bluetooth SIG consisted of Ericsson, IBM, Intel, Nokia, and Toshiba.

By June 2001, the member list of participating companies exceeded 2400. The role of the SIG is to develop the specifications for Bluetooth as per the requirements, promote and market the technology and brand name, handle legal and regulatory issues, and certify the Bluetooth products that meet the conformance and interoperability requirements. Any company, by signing a zero-cost agreement, has complete access to the SIG specifications and can qualify for a royalty-free license to build products based on the Bluetooth technology.

The Bluetooth SIG completed the initial specification work and released the first version of the official Bluetooth standard in July 1999.

Data in GSM Networks

The Global System for Mobile Communication (GSM) is a multiservice cellular network. It provides not only voice service, but a good set of data services as well. This chapter describes the data services offered by a GSM network. It describes the data services before the advent of GPRS and EDGE.

The GSM data services can be categorized in terms of traffic, signaling, and broadcast channel data services. The GSM standard specifies data services on the traffic channel (TCH), which can be utilized by data applications such as fax and Internet service provider (ISP) connection. This is also referred to as circuit switched (CS) data service. The data service on a signaling channel is known as the point-to-point short message service (SMS). Using SMS, a subscriber sends or receives a short string of text (maximum 126 characters) using a signaling channel. There is another type of SMS service called SMS broadcast, which is the only broadcast channel data service. This service transports data on a specially defined broadcast channel to all the subscribers in a cell. The broadcast data applications, such as traffic reports and weather alerts, were anticipated to use this service, but it didn't get much attention in deployment from cellular service providers.

CYBER FORENSICS

Cyber forensics can be defined as the process of extracting information and data from computer storage media and guaranteeing its accuracy and reliability. The challenge of course is actually finding this data, collecting it, preserving it, and presenting it in a manner acceptable in a court of law.
Electronic evidence is fragile and can easily be modified. Additionally, cyber thieves, criminals, dishonest and even honest employees hide, wipe, disguise, cloak, encrypt and destroy evidence from storage media using a variety of freeware, shareware and commercially available utility programs.
A global dependency on technology combined with the expanding presence of the Internet as a key and strategic resource requires that corporate assets are well protected and safeguarded.
When those assets come under attack, or are misused, info security professionals must be able to gather electronic evidence of such misuse and utilize that evidence to bring to justice those who misuse the technology.
Cyber forensics, while firmly established as both an art as well as a science, is at its infancy. With technology evolving, mutating, and changing at such a rapid pace, the rules governing the application of cyber forensics to the fields of auditing, security, and law enforcement are changing as well. Almost daily, new techniques and procedures are designed to provide info security professionals a better means of finding electronic evidence, collecting it, preserving it, and presenting it to client management for potential use in the prosecution of cyber criminals.

Internet Registries

Three regional Internet registries are responsible for the assignment of IP addresses and autonomous system numbers globally (other organizations are responsible for the assignment of domain names):

• ARIN— American Registry for Internet Numbers
• APNIC— Asia Pacific Network Information Centre
• RIPE— Réseaux IP Européens

ARIN is a nonprofit organization established for the purpose of administration and registration of IP numbers for the following geographical areas: North America, South America, the Caribbean, and sub-Saharan Africa.

APNIC represents the Asia Pacific region, comprising 62 economies. It is a not-for-profit, membership-based organization whose members include Internet service providers, national Internet registries, and similar organizations.

RIPE is an open collaborative community of organizations and individuals operating wide area IP networks in Europe and beyond. The objective of the RIPE community is to ensure the administrative and technical coordination necessary to enable operation of a pan-European IP network. RIPE has no formal membership, and its activities are performed on a voluntary basis.

Satellite Communication Systems

The era of satellite systems began in 1957 with the launch of Sputnik by the Soviet Union.
However, the communication capabilities of Sputnik were very limited. The first real communication
satellite was the AT&T Telstar 1, which was launched by NASA in 1962. Telstar 1
was enhanced in 1963 by its successor, Telstar 2. From the Telstar era to today, satellite
communications [16] have enjoyed an enormous growth offering services such as data,
paging, voice, TV broadcasting, Internet access and a number of mobile services.
Satellite orbits belong to three different categories. In ascending order of height, these are
the circular Low Earth Orbit (LEO), Medium Earth Orbit (MEO) and Geosynchronous Earth
Orbit (GEO) categories at distances in the ranges of 100–1000 km, 5000–15 000 km andapproximately 36 000 km, respectively. There also exist satellites that utilize elliptical orbits.
These try to combine the low propagation delay property of LEO systems and the stability of
GEO systems.
The trend nowadays is towards use of LEO orbits, which enable small propagation delays
and construction of simple and light ground mobile units. A number of LEO systems have
appeared, such as Globalstar and Iridium. They offer voice and data services at rates up to 10
kbps through a dense constellation of LEO satellites.