The main two types of computer modems are – internal and external.Internal modems, as the name itself suggests, is included in the expansion card slot inside the computer. Are available options for ISA and PCI. In addition, versions are available RSMSIA / PC Card for use with laptop computers. The internal modem does not take extra space on your desk, but you have to open the computer case to install it. Generally, internal modems are a bit cheaper than the same model in an external configuration. Configuring the internal modem may require to switch jumpers on the board to select the IRQ and I / O address. In this respect, the modem configuration resembles the configuration of network interface card. The modem must be configured to use the COM port that is not used by another device. Devices using COM ports are pointing devices, scanners, cradle for handheld computers and other devices that use a serial connection. Software drivers for the modem must also be installed.
If the modem is Plug and Play (PnP) and PnP model is supported by both BIOS-but the system and the operating system may not need manual configuration. The other type of computer modem is external computer modem. External computer modems typically cost slightly more than domestic, but they offer several advantages. No need to open the box and install the card. Just plug the modem into the serial port using a serial cable. With the new USB modems include such computer modem into a USB port or hub. This type of computer modem use IRQ and I / O address, set the serial port to which the modem is connected, so usually require fewer configurations, although this benefit may be negated by using an internal PnP modem. Typically, external modems have indicator lights or lights on the state in which you find out when the modem is on-line when transmitting or receiving data, etc.
Some internal modems are also indicator lights, but they are not always visible to the user because they are on the rear panel of the computer. Modems are produced as two physical types: internal and external. Each of the two types has its advantages and disadvantages. Depending on the type, the configuration is slightly different for the two types. Both modems are serial devices, which mean that bits are transmitted sequentially one by one on the line. The advantage of the internal modem is its compactness. It is an electronic controller (PCB), which is included in the ISA or PCI slot inside the computer. That means not taking up extra desk space and does not require the purchase of a serial cable, because often it is missing in the kit.
Typically, internal modems are more complex to configure than external. Internal modems generally provide a way to change the configuration settings. Depending on the manufacturer and model, you can change the settings of IRQ, I / O addresses and COM ports using: DIP switches, jumpers and Software. Many modern modems support the technology Plug and Play, which allows the operating system automatically detects the device, install the necessary drivers to find the necessary resources available to pay for the device. By user requires very little intervention. External modems have two advantages over domestic: most external modems have a status indicator light that shows when the modem is powered on when it is connected or when implemented data transfer, external modems are generally easier to install and configure them. This type of computer modem needs no switches or jumpers to set up and no need to open the computer case.
External modems use a separate power source, as opposed to internal use, on the computer. The serial cable connects the modem to a serial port (COM) on the rear panel of the computer. To use an external modem, you need a free serial port. Most computers have two: COM1 and COM2.