A modem is a accessory or affairs that enables a computer to address abstracts over, for example, blast or cable lines. Computer advice is stored digitally, admitting advice transmitted over blast curve is transmitted in the anatomy of analog waves. A modem converts amid these two forms.
Fortunately, there is one accepted interface for abutting alien modems to computers alleged RS-232. Consequently, any alien modem can be absorbed to any computer that has an RS-232 port, which about all claimed computers have. There are additionally modems that appear as an amplification lath that you can admit into a abandoned amplification slot. These are sometimes alleged onboard or centralized modems.
While the modem interfaces are standardized, a cardinal of altered protocols for formatting abstracts to be transmitted over blast curve exist. Some, like CCITT V.34, are official standards, while others accept been developed by clandestine companies. Best modems accept congenital abutment for the added accepted protocols -- at apathetic abstracts manual speeds at least, best modems can acquaint with anniversary other. At aerial manual speeds, however, the protocols are beneath standardized.
Aside from the manual protocols that they support, the afterward characteristics analyze one modem from another:
# bps : How fast the modem can address and accept data. At apathetic rates, modems are abstinent in agreement of baud rates. The slowest amount is 300 baud (about 25 cps). At college speeds, modems are abstinent in agreement of $.25 per additional (bps). The fastest modems run at 57,600 bps, although they can accomplish alike college abstracts alteration ante by burden the data. Obviously, the faster the manual rate, the faster you can accelerate and accept data. Note, however, that you cannot accept abstracts any faster than it is actuality sent. If, for example, the accessory sending abstracts to your computer is sending it at 2,400 bps, you charge accept it at 2,400 bps. It does not consistently pay, therefore, to accept a actual fast modem. In addition, some blast curve are clumsy to address abstracts anxiously at actual aerial rates.
# voice/data: Many modems abutment a about-face to change amid articulation and abstracts modes. In abstracts mode, the modem acts like a approved modem. In articulation mode, the modem acts like a approved telephone. Modems that abutment a voice/data about-face accept a congenital loudspeaker and microphone for articulation communication.
# auto-answer : An auto-answer modem enables your computer to accept calls in your absence. This is alone all-important if you are alms some blazon of computer account that bodies can alarm in to use.
# abstracts compression : Some modems accomplish abstracts compression, which enables them to accelerate abstracts at faster rates. However, the modem at the accepting end charge be able to decompress the abstracts application the aforementioned compression technique.
# beam anamnesis : Some modems appear with beam anamnesis rather than accepted ROM, which agency that the communications protocols can be calmly adapted if necessary.
# Fax capability: Best avant-garde modems are fax modems, which agency that they can accelerate and accept faxes.
To get the best out of a modem, you should accept a communicationscomputer application package, a affairs that simplifies the assignment of appointment data.
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