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Winmodems™, Software, Soft & HSP Modems

"Winmodems are no good".... or worse, is a much believed falsehood.

If you surf around the 'net, or monitor news:comp.dcom.modems, you're likely to see people resorting to 4-letter words to describe their hatred for "Winmodems™"). Like most products, there are good and bad ones, but the fact that there were (and are) Winmodem "lemons" is not cause to dismiss the entire lot.

"Winmodem" (WM hereafter) is a registered trademark of 3Com/US Robotics, but the mark is widely used to refer to any modem made by anyone that depends upon an operating-system driver in order to function. Traditional external modems are interfaced to the computer system through a serial port (also COM port, RS232 port, Asynch, etc.), and cannot be a WM. Traditional internal modems look like a standard COM port to the computer; WMs, or "soft" modems on the other hand have some of the functions of the modem performed by the PCs processor, and through the driver, emulate a standard COM port so standard modem applications function.

My first experience with a WM was a Cardinal product (28.8k) using a Rockwell chipset. This modem was junk. I can see how WMs got their bad reputation. Some WMs (3Com/USR) today still are provided with drivers that won't allow the modem to operate in a DOS box under Windows. On the other hand, IBM has OS/2 drivers today for the Lucent LT Win Modem.

I've happened upon systems that are using 3Com 56k WMs, and they work; however, I'd never buy a 3Com WM because of the lack of support for a DOS box, or support for NT for their retail versions. (Note - WindowsNT is supported on some OEM versions of the 3Com WM.)

There are actually 2 types of software modems: those that contain a DSP (digital signal processor), and those that don't (usually referred to as Soft or HSP modems). There is a big difference in the load these 2 types place on your CPU. See this Lucent-sponsored page [which in my opinion is incorrect as it refers to only 2 types of modems - hardware and software, and would classify a modem that has a DSP but requires an OS-specific driver as a hardware modem].

My most extensive experience has come with my PC (IBM-Aptiva) - a "LT Win Modem", and I'm very impressed. It's a product I would now purchase if I needed a modem. (See LT Win Modem page and Should You Buy a 56k Modem?)

"Winmodems" will tax your CPU

Not necessarily true. Ed Schulz, who works for Lucent, had this to say in a newsgroup reply:

> I was told by somebody that LT Win modem requires a Pentium 133 or higher speed PC but I only have a Pentium 100 and that's why it is slow

Ed Schulz wrote:
Absolutely untrue.  I am connected now using our reference LT Win Modem using recent production drivers at 48k.  This is running on a 486 DX2/66.  My mother runs her LT Win Modem on a 75 MHz Pentium with no problem.

In one lab study, the CPU load of our modem host controller was less than that of the Windows serial driver handling a standard external modem while downloading identical files at identical DCE rates.  The fear that a well designed "Win Modem" will tax your precious CPU cycles is simply not true.

There are many variations on the design of WMs, and I'm not familiar with all of them. Personally, I'm still skeptical enough about WMs that I'd tend to avoid WMs that are not Lucent-based, but the LT product has me convinced that Ed's statement above is correct - and, that the Lucent-based product is "well designed". Note though that many companies make WMs based upon the Lucent chipset, and they probably aren't all the same in terms of quality and design.

There are differences in the designs of WMs. Some, like the Rockwell/Conexant Soft56, PCTel, and others have the host processor (your PC's CPU) do all of the work, and require a MMX processor. The modem is little more than a cheap chip and software, and should be avoided! The better design has a powerful DSP chip (effectively a CPU) on the modem, and the host processor has a significantly lower load.

What's the difference between a "real" modem and a Winmodem?

Yes, some detractors insult the WM name by implying it is not a real modem. A "real" modem has a controller and interfaces to a PC (or other device) that outputs asynchronous serial data - through a COM port on a PC. The modem hardware then does all sorts of processing to this data, to convert it to the analog phone line output representing synchronous serial frames of data conforming to the protocols in use. Some of this processing is done by the PCs CPU in a WM, and the resulting data is transferred to the modem card through a "virtual" COM port. (A WM doesn't actually use a COM port, but since all modem application software is designed to use a COM port, the WM driver emulates a physical port so that communications software applications will work.) In a "well-designed" WM, the extra load on the CPU to do the processing a "real modem" performs is substantially offset by eliminating CPU load involved in the transfer of data over the COM port to a "real modem". The amount of processing done by the CPU instead of the modem, and the resulting effect on PC performance varies widely among different WM designs and products. It's extremely difficult to find the technical description of any vendor's WM implementation, so you can't go wrong by insisting on a "real" modem; but, you can find some well designed WMs that may serve you well until all of today's analog modems are history.

Also see:
Rockwell HCF Modem
Lucent LT Win Modem
Rockwell/Conexant V.90 Product Overview
Rob Clark's 'Winmodems are not Modems' -
Modems, Winmodems  & Linux


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