Tuning Modem Performance in Windows 3.x

Of course, all of the following assumes that the Trumpet Winsock stack is in use (see my main page).

For better utilization of the 16550 FIFO in the modem, get cyberdrv.zip from the US Robotics website. The INSTALL procedure updates SYSTEM.INI to replace the COMM.DRV serial i/o driver with CYBERCOM.DRV. It has my seal of approval. There is documentation that gives better explanations of what it does. I installed it and the following on my machine, and the difference in NetScape was amazing!

The following are extracted from various WINSOCK FAQs I found while searching for WinSock client source code from http://www.well.com/user/nac/alt-winsock-faq.html



   (If you're using a COM port other than 1, change the com1 to com2, 


For further info on how to set up the Trumpet WinSock, see MTU and MSS and Communications Tuning.FAQ. Here is a local mirror of the busy FTP site Communications Tuning.FAQ. An excellent discussion of troubleshooting Trumpet problems and optimizing modem throughput is available here.

After reviewing all of the information provided, I chose to keep the Trumpet defaults. They are giving good performance with the changes earlier here.

I usually load up TCPMETER.EXE, which comes with Trumpet's WinSock. This gives a graphic representation of the data thruput of the modem. There is no documentaion, but... The green at the top is incoming data, the red at the bottom is outgoing data. The menu bar indicates full-scale scale. At 28800, I use 4096. Left mouse click increases the scale, right button decreases it.

ModemSta is a nifty shareware program shows the speed, the modem indicator lights (which are invaluable for knowing when the phone line has been dropped) and counts bytes TD and RD, for a numeric representation of thruput, among other things.

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