LinModems?

Polo was the first of several to send us an article over at LinuxWorld about PC-Tel announcing LinModems, eg, software modems that can run under Linux as well. Some interesting comments in there about hardware modems being a "Luxury" item. Kinda amusing.

Comments

What planet are these people from?

[DeadFish]

Although a hardware modem can cost up to five times more than a software modem,t hey are relatively cheap, with a current price tag at $100... ... 'I think that [in the future], a hardware modem will be a high-end luxury item'"

Okay. So even though hardware modems are *already* fairly inexpensive and will continue to go down in price, they are going to be high-end luxury items? $100 is not a high-end luxury price. The only way anyone could consider a modem high end is if everything else available was complete garbage. Of course, this *is* the prediction of a winmodem software manager

Personally, I fail to see how, with DSL, cable, and ISDN becoming cheaper and more available, any modem could be considered "high end". If you want high end connectivity, why modulate and demodulate a bunch of analog signal?

Traditionally, software modems have a bad reputation in the linux community. In fact, they've earned the nickname "WinModems" because many are optimized to work with the Microsoft Windows operating system, and refuse to cooperate with any other OS.

Funny, I always thought they "earned the nickname WinModems" because they say "WINMODEM" on the frigging box. It's the fricking model name, not a nickname.

They do not just have a bad reputation in the linux community, they have a bad reputation among just about anyone with any idea how modems work. And it's not because they aren't very cross-format, it's because they are lousy modems. I work at an ISP, and I can say with some certainty that the loathing and contempt our tech support has for WinModems is *not* because they only work on windows, but because they barely work at all

Phew. Felt good to get that out. So anyway. What planet did these people say they were from?

Re:Quality of Service

[Mr Z]

You mentioned the following:

Rather, in order to correctly interprete the wave signals from the modem in software required that the driver execute at specific times.

For a perfect software modem, yes, this is true. But for a simple software modem, there are many things you can do to be "good enough", including the following:

• Buffer up alot of samples to increase your tolerance for latency. The buffering could occur via DMA to system memory, I imagine.
• Run as a real-time task or interrupt driven device driver to place your priority over the rest of the tasks on the system.
• Treat dropped samples as line noise and just request a retransmit if you can't error-correct the glitch.
• If you miss getting samples out to the board in time, no worries -- replay your previous samples and pray the link was idle so it just looks like the idle-time carrier. If it wasn't, the remote modem will behave as if it were line noise and all will still be well.

After all, Win9x has the same problems as Linux does in this regards (eg. no guaranteed hard-real-time scheduling), yet software modems seem to function passibly in such an environment. If anything, Linux would probably do better than Win9x at this same task. In any case, missing a real-time deadline with a soft-modem would look like lag to the end user and little else. Annoying, but not fatal.

Now, I'm not running out and signing up to buy a soft modem (particularly since I'm about to get DSL service, obviating the need for a POTS modem almost entirely), but there are some interesting ideas that could make LinModems popular, depending on how open PC-Tel is.

• Software modem lights that actually work. (The ones I've seen in the past were worthless for actually diagnosing modem troubles. Eye candy at best.)
• Real-time modem connection quality statistics, such as number of retrains, current symbol rate, etc... perhaps via an entry in /proc. The more detail, the better.
• General on-the-fly control of modem parameters, such as explicitly requesting fallback/fallforward. For instance, lower symbol rates tend to work alot better for interactive sessions since latency is lower, but higher symbol rates tend to be better for downloading. You could actually request the modem to fall forward or fall backwards by signalling the driver directly. You can't really do that with an external modem.

--Joe

--

Only a good thing if the driver's free software

[Bruce Perens]

This would only be a good thing if the driver is free software. That would give us a chance to play with modulation schemes, etc., as ham radio operators are doing with sound cards - they've implemented radio modems in the linux kernel, using nothing more than a sound card for hardware.

Without a free software driver, we're stuck with a dumb piece of hardware and a closed driver. No thanks. The embedded intelligence in a modem doesn't cost more than $10, so I doubt that would fly.

I'd really like to encourage these guys...

Thanks

Bruce

Re:Maybe They'll work better...

[rde]

You won't see improvements, you didn't get first post, and Suse 6.2 is just about out (if it isn't already).
Happy birthday.

Re:Isn't this kind of hypocritical?

[dirty]

I have to disagree with the "another driver running as root" concern you brought up. By that logic linux shouldn't support ANY new hardware, since all drivers run in kernel mode (which is actually more privlaged than root) and can do anything they gosh darn please to do. Then again hardware is pretty much in the same situation.

Software modems themselves are bad. But they do allow for some really cool hacks. You could build an ultra cheap PBX out of some of these, or answering machine, or something else. Think of it more as a computer interface to a phone. Even TCP/IP telephony would be more attractive with a real phone.

If this company sells them cheap enough, and makes the docs completely open, I might pick up some and hack away. I'd never use one of these things as a modem though. Maybe it's just me but I don't think the $5 I'm gonna save is worth the CPU time it's gonna cost me.

winmodems aren't so bad

[bloosqr]

I know I am probably going to be flamed for this but I don't think winmodems are really such a bad thing for home use in the same way IDE drives are not so bad for home use. I have an 28k external modem for my linux mach. and a 56k internal which i basically got for free from tigerdirect when I bought my machine.

I think if you are logged in all day and run jobs in the background on a regular basis then by all means you should get a real modem, but to be honest everything i've ever done on the windoze side of the box (which basically involves downloading the random piece of software) the winmodem has pretty much worked exactly as specified and i get 56k transfers basically for free (which isn't so bad really).. running netscape isn't exactly CPU intensive :) Moreover, just to test out what the degradation really was like, I had the machine play mpegs (video) (I have no mpeg card so it was softwarebased decompression) at the same time and got less than 10% loss, still well above a typical 28k modem.
(Incidentally the box is an AMD 350-K2 w/ 64
megs of sdram, to give you an idea of the power)

I think if you are trying to build a $200 box for your parents so they can send email, read cnn news and other crap, winmodems are the way to go, since one of the nice things about linux is legally building costeffective machines where every penny counts, i think it would be nice to take advantage of the cheap hardware. (In the same way we now all take advantage of cheap IDE drives which are also more cpu intensive than your typical SCSI drive at home)

just so you know, more than likely if i actually buy a modem it'll be external etc but thats only because most of us are more than typical online users. (Incidentally i think i'll switch to SCSI as well next time around, mostly because 4 IDE device limit is out of control) but again the performance loss is really negligable as far as I can tell for doing typical home use stuff (not games obviously) but real_audio,surfing,email etc..