A modem is a peripheral device used to transmit information over a telephone line. The word itself is derived from the abbreviation "modulator-demodulator".
Instructions
Step 1
Modems are subdivided into external, internal and built-in modems according to their design. External modems are connected via USB, COM or LPT port, or using the RJ-45 connector in the network card (Ethernet interface). They usually have a separate power supply, but there are modems that are powered by USB. Internal modems are installed on the computer motherboard using one of the following interfaces: PCI, PCI-E, PCMCIA, ISA, CNR, or AMR. Built-in modems are one part of the device in which they are built, such as a laptop.
Step 2
According to their principle of operation, modems are divided into hardware, software and semi-software. In hardware modems, all work is carried out due to the computer built into it. In addition, it contains read-only memory (ROM), it contains the microprogram that carries out control. In software modems, all tasks are performed by the program, and the computation load is performed by the central processor. In semi-software modems, the computer's central processing unit performs only a certain part of the tasks.
Step 3
By the type of connection, modems are subdivided into: - dial-up telephone line modems; - ISDN-modems (intended for digital telephone lines); - DSL-modems (designed to create leased lines, a telephone network is used, they operate in a frequency range that differs from that used by dial-up telephone line modems); - cable modems (special cable lines are used for their operation); - radio modems (use a radio channel for their work); - cellular modems (work on the basis of GPRS, EDGE, 3G, etc., often made in the form of a key fob); - satellite (work with a satellite signal); - PLC (electrical network cables are used for work).
