Windows modem driver speed

[Zosimos]

I've got a WEIRD problem with serial port speed and an external modem. My modem is a USR Sportster 33.6 Faxmodem and I've been using it successively with Win 3.1, Win 95, and now Win 98. Note, these were each SEPERATE installs, not upgrades, so I don't see how it could be a driver being carried over. The serial port is at 115200 already. And this works ok as long as the modem is set for 57600, NOT 115200. The various settings have been properly tuned and I get almost max throughput (up to 57600) all the time. But, the modem is rated to be able to handle 115200 and it WORKS at that speed with DOS applications. If I could get it to work at that speed in Windows I'd get the full benefit of the compression. I've been struggling with it on and off for years, but it's never worked at this speed. If I tell Windows to address the modem at 115200 the throughput gets completely trashed. I get 800-1000 cps at best. The modem lights flicker slowly, as if it's getting the data at full speed but has to halt because it cannot get it into the computer, while they flicker very quickly at the 57600 setting and the data flows smoothly. I've tried all sorts of settings, checked the port speeds and all windows settings dozens of times. I've tried every vaguely compatible driver. Nothing helps. Set the modem speed back to 57600, and it kicks booty again, up to that 57600 limit! I want the 115200, but something in Windows won't accept that this modem can do 115200 even if I set it in Windows own config dialogues. There must be a registry setting or something that is causing this bottleneck? Oh, I do know about the need to use &W to reset the modem baud rate in NVRAM. Even this does not help. I can set the modem to use 115200 internally but windows still cannot deal with it unless it is told to use 57600. With the MODEM and PORT at 115200, but the Windows driver at 57600, I get almost maximum throughput all the time. This tells me that I could be getting much MORE throughput than 57600 if Windows would deal with the modem at 115200. ?????

 

[Comtech]

Let's see. A 33600bps modem is giving you throughput of 57600bps. Right. Even a 56k (56000bps) modem can't come close to 115200bps.
What is the problem? Cheers,
Jim
reboot@pcmech.com

http://members.cnx.net/reboot/

Moderator at

http://www.56k.com

Staff at

http://www.pcmech.com

Windows 9x/ME instructor.
Jim's Modems:

http://reboot.8m.com/

 

[Zosimos]

The problem is that a 33.6 modem CAN come close to 115200 with compression. Text compression of 3 or 4 to 1 is possible on many web pages. But the compression doesn't do me any good if my computer won't accept the data any faster than 57600. A few days ago I accidently 'jammed' the port somehow. The driver or whatever it is that screws me up could not reset the port speed and it stayed at 115200. I got 8k, 9k, and even a full 11.5k throughput on some pages. Then after a few hours of fun I had to reboot. End of performance. I don't know how to duplicate it or I would. The thing that clued me in was that the port could not respond to a hangup from Windows. I kept clicking the 'Disconnect' button but it would nto disconnect. The port hardware control registers were screwed up and that's why it stayed at full speed.