DSL Softmodems
Although the term has historically been used to indicate the traditional "analog" PSTN software modems, there are some software-based DSL modems or even routers, which work on the same principles as their PSTN ancestors, only on a larger bandwidth and on a more complex signal. One of the first software based DSL modem chipsets was Motorola's SoftDSL chipset, for which similar considerations as "ordinary" PSTN modems can be made. The term WinDSL has shown up on technology sites like Slashdot regarding this trend. DSL softmodems generally require the same interfaces as PSTN softmodems, such as USB or PCI.
However, the increasing popularity of home networking limited the prospects for DSL softmodems. Many households and small businesses have a router connected to the DSL modem, and all their computers are connected by various types of wired or wireless networks to that router. For that reason, most broadband modems today (cable as well as DSL) are external devices with either Ethernet connections for single PCs or routers, or built-in routers of their own; these interfaces require a full-hardware implementation. Most current broadband modems with USB jacks also have Ethernet jacks, and thus are full-hardware modems.
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