Modems are devices that are used for communicating with other PCs over common telephone lines. modems come in many different types, internal, external and acoustic. Internal modems a installed inside the system and have two jacks for connecting the phone line and a handset. External modems are connected to the system on the outside and generaly have a serial cable for transfering data back and forth to the system from the modem. Acoustic modems (very old ones) are also connected by a serial cable but have a rubber set of cups that are placed on the microphone and earpeice of the phone, these types are rarely used today. There are a variety of internal modems on the market today, ranging from standard 56k V.90 with voice to Winmodems. The differance will depend on what you want to do with the modem and the level of reliability you want. Winmodems for example have only a portion of the logic circuitry that is required to make it work, the remaining of the nessesary logic and control is used from the operating system (Windows). In many cases these modems will work fine, however they don't work and play well with all programs and can cause conflicts with other devices. They are however the least expensive of all the modems generaly costing around $20.00 Good reliable modems that will work with any progam would consist of a jumper set on the adapter card for setting the comm port and interupt manually and are plugged into an ISA slot on the mainboard, thus the system can not change the settings at it's will. Some programs must see the modem at a "traditional" system location and will not work properly unless it's there lending to problems with PCI type modems that are "Plug & Play" where the system decides where it's located in memory and hardware. The overall best and most reliable modems are external, these modems afford much better control and quite often have superior filtering built into them. They also provide the ability to power them down for resetting independanty from the system in the event of a problem on the phone line that hangs the modem thus eliminating the need to shutdown and restart the entire system to reset the modem. External modems also have there own power supply that plugs into the wall or power strip thus not robbing the system of power for it's needs. These modems are the most expensive of all the modem types, however they are also the best ranging in price from $100.00 to several hundred dollars, averaging about $150.00 or so.
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