What Is Modem??

Short for modulator-demodulator. A modem is a device or program that enables a computer to transmit data over, for example, telephone or cable lines. Computer information is stored digitally, whereas information transmitted over telephone lines is transmitted in the form of analog waves. A modem converts between these two forms.

Fortunately, there is one standard interface for connecting external modems to computers called RS-232. Consequently, any external modem can be attached to any computer that has an RS-232 port, which almost all personal computers have. There are also modems that come as an expansion board that you can insert into a vacant expansion slot. These are sometimes called onboard or internal modems.

While the modem interfaces are standardized, a number of different protocols for formatting data to be transmitted over telephone lines exist. Some, like CCITT V.34, are official standards, while others have been developed by private companies. Most modems have built-in support for the more common protocols -- at slow data transmission speeds at least, most modems can communicate with each other. At high transmission speeds, however, the protocols are less standardized.

Aside from the transmission protocols that they support, the following characteristics distinguish one modem from another:

• bps : How fast the modem can transmit and receive data. At slow rates, modems are measured in terms of baud rates. The slowest rate is 300 baud (about 25 cps). At higher speeds, modems are measured in terms of bits per second (bps). The fastest modems run at 57,600 bps, although they can achieve even higher data transfer rates by compressing the data. Obviously, the faster the transmission rate, the faster you can send and receive data. Note, however, that you cannot receive data any faster than it is being sent. If, for example, the device sending data to your computer is sending it at 2,400 bps, you must receive it at 2,400 bps. It does not always pay, therefore, to have a very fast modem. In addition, some telephone lines are unable to transmit data reliably at very high rates. 

• voice/data: Many modems support a switch to change between voice and data modes. In data mode, the modem acts like a regular modem. In voice mode, the modem acts like a regular telephone. Modems that support a voice/data switch have a built-in loudspeaker and microphone for voice communication. 

• auto-answer : An auto-answer modem enables your computer to receive calls in your absence. This is only necessary if you are offering some type of computer service that people can call in to use. 

• data compression : Some modems perform data compression, which enables them to send data at faster rates. However, the modem at the receiving end must be able to decompress the data using the same compression technique. 

• flash memory : Some modems come with flash memory rather than conventional ROM, which means that the communications protocols can be easily updated if necessary.

• Fax capability: Most modern modems are fax modems, which means that they can send and receive faxes.

To get the most out of a modem, you should have a communications software package, a program that simplifies the task of transferring data.

How to Avoid Getting a Computer Virus or Worm on Your Windows PC

Email is one way infections can enter your computer from the internet. Below are some tips on stopping viruses or spyware from attacking your system through e-mail.


Steps:

1. Never click on a link or attachment in an email that you are not positive is from a trusted source. If you think the e-mail looks suspicious, it probably is. It never hurts to send an email to verify that this is legitimate.
2. Be careful about using Microsoft Outlook. Outlook is more susceptible to Virus and Spyware infections than other e-mail programs, unless you have efficient Anti-Virus programs running. There are many other free e-mail programs available that you can use, or a web-based program such as Hotmail or Yahoo to avoid these problems. You may also try Outlook anti-spam addons freely available on Microsoft's Web site.
3. Install an Anti-Virus program (ex. Norton, F-Secure, Sophos, McAfee, or AVG). Also available is the free AntiVir virus scanner. Make sure you keep your virus definitions updated and run a full system scan weekly.
4. Install an Anti-Spyware program (ex. Ad Aware SE, Windows Defender, Malwarebytes, spybot), that operates against internet malware and spyware. Just like Anti-Virus, keep it updated, and do a full system scan weekly. Often these anti-spyware programs will find problems that anti-virus programs overlook.