What is a Modem?

The name modem evolves from the term Modulator-Demodulator. It is a device that modulates an analog carrier signal to encode digital information, and also demodulates such a carrier signal to decode the transmitted information.

It is the device used for connecting and accessing the internet in the domestic sphere.

History of Modems

The first types of modems ever used were the ones used by The United States Air Force for communication between radar stations, air bases ad command centers. They worked on a simple phone line system (the twisted copper wires). The idea for using modems was derived by the telegraph system.

The early modems were called voice band modems, which worked on the binary system. The voice band modem used to turn the digital 1s and 0s of a personal computer into sounds that can be transmitted over the telephone lines of Plain Old Telephone Systems (POTS), and once received on the other side, it converted those 1s and 0s back into a form used by a USB, Ethernet, serial, or network connection.

The first commercial modem was the Smart Modem, which was launched by US Robotics in 1981. It was a modem with the capacity to send/receive data at 300 bits per second. It was attached to a small controller that let the computer send commands to it and enable it to operate the phone line. The command set included instructions for picking up and hanging up the phone, dialing numbers, and answering calls, and this made it the first modem that had a number of functions that we see today, i.e., making and receiving calls, faxes et al.
Present day modems

The modems used these days are classified into two types: Fixed line modems and radio modems.

The fixed line modems are the most used ones, due to their commercial availability and they are also very pocket friendly. Under the fixed line modems we have Dial-up modems, Broadband modems and USB modems.

The radio modems include WiFi and WiMax technology modems.

Fixed Line modems

The dial-up modem is one of the most widely used modems in the world. It usually works at speeds varying between 33 kbps and 56 kbps. It uses a phone line connection to access the internet. It connects to the PC using either a serial, parallel or USB connection if it is an external modem, and is attached to the motherboard if it is an internal one. It connects to the phone line using a RJ-11 jack. It connects by dialing a number to the service provider, and hence a connection is established. It is slow and depends on the availability of the network and congestion. The billing is also done just as a phone call is, that is on the basis of the pulse of the telephone.

The USB/PCI laptop modems are dial up modems for more portability, and are used mostly for laptops, but are compatible with desktops also. It is best suited for travelers and professionals who need access to internet at all times. They work on a microwave/mobile network technology, the same that cellular phones use (CDMA or GSM). They also dial a number to the service provider but the difference is that they use a cellular network instead of a landline. A USB modem operates either through USB port or PCI slot.

The broadband connection is the most popular form of connectivity due to its high speed. The speed ranges from 128kbps to 2mbps, which is suitable downloading multimedia. They are more secure than dial ups as they support firewalls and other security measures. They work either on a RJ 45 jack or a USB port. Many broadband modems include the functions of a router (ethernet/WiFi), which enables the user to setup a small home network too. It is much more economical as compared to dial ups as it does not work on the pulse system and hence is not fully dependent on phone line.

Major Service Providers of Broadband connections

BSNL/MTNL
Tata Telecom
Reliance Communications
Bharti AirTel

Major Modem Brands

Motorola (Better for radio modems)
Beetel (provided with all major service providers as the default modem)
Logitech

What to look for when buying a modem

Compatibility with the motherboard (in case of internal modem)
Speed of connection
Connectivity with the Motherboard (in case of external modem, serial, parallel, USB, Firewire, RJ45, RJ11)
Portability and network availability, in the case of USB modems.

So friends here we are going to discuss about solutions of problems which come after removing viruses..

so lets first start with major problem which is non opening of drives on double click so what to do for it itz so simple you can make

your drives work after tweaking some data in registry so now i am going to tell you which data u have to tweak.

1-Goto Start-Run and in run command panel type regedit.

2-In Registry Edit window you saw some list these are the registry information of your whole system.

3- In that goto HKEY_CURRENT_USER---Software---Microsoft---Windows---Explorer---MountPoints2

thats it now your are in core registry of your drives in mountpionts u saw your drives key also like C,D,etc

in those drive keys delete all binary value except Default and Base Class.

after deleting crap values close registry editor and goto my computer and open your drive now your drives will open on

double click.

Another major issue which come is you are not able to see hidden files in your pc.

1-For that again open registry editor goto HKEY_LOCAL_MACHINE---Software---Microsoft---Windows---CurrentVersion---Explorer---Advanced---Folder---Hidden in this key value you will see two more keys change nohidden checked and default value to 2. and in show all change first one to 1 and second one to 2. thats it now you can open hidden files in ur pc.

if you have a problem like task manager option is blocked or registry editor is not opening then for that again goto run this time write GPEDIT.msc after typing this a new window will open in that window goto ctrl-del-options goto remove task manager and set it to disabled..

If u got any problem while performing feel free to ask i will help you.

r read permission

w writepermission

x the shell will attempt to execute the fie when its name is entered as command

Read permission means the contents of the directory can be listed with “ls” command

Write permission means can we make files in directory

Decimal values for folder permission

Read 4

Write 2

Execute 1

Permission set to a folder

Command is

Chmode 7 6 4

Eg chmode 4+2+2 user 4+2 group 4 others

1. Shut computer down

2. Step 2

   Disconnect all components from the back including power

3. Step 3

   Remove side panel- all computers are a little different this may need a screwdriver and two screws to remove or it may be as simple as a plastic button to push on top and/bottom.

4. Step 4

   Once side panel is removed you will be able to see the cooling fan and/or cooling fan channel (green) if you have the channel then it will need to be removed

5. Step 5

   Plug in your vacuum to a GROUNDED outlet. you will need a vacuum with a hose attachment and plastic ends.

6. Step 6

   Vacuum dust and debris from heat sink (metal piece). careful not to push on or move this piece it is protecting your processor.

7. Step 7

   Vacuum cooling fan. be careful not to touch this fan with anything as the blades will turn extremely fast with the vacuum.

8. Step 8

   You should also take this opportunity to vacuum any other dust or debris from the base of the computer careful not to touch any of the components.

9. Step 9

   Follow these directions in reverse to put things back together.