MODEM University by GM Raymond

The intent of this article is to tell you enough about modems to survive, install or upgrade your modem with minimum hitches. Although geared for Windows 9x users, the basic information can be applied to most all other platforms.

MO-dulatorDEM-modulator, that's the modem. I remember my first 300 baud PC modem. Then came 1200 and I was amazed. I have been amazed ever since. There was a time when a commonly heard mantra was, "nothing can go faster". That was when 9600 was in its hay day. That mantra has been pretty much silenced as new breakthroughs are occurring almost every few months.

In the last few years 57,600, or 56K as it is now more commonly known, has become rather commonplace. Fortunately or unfortunately, competition resulted in two standards. Kflex protocol, controlled by Rockwell and X2 controlled by US Robotics. However, if the Internet was to continue growing, a more universal standards was needed.

So, the International Telecommunications Unions passed an imprimatur on v90. This new protocol was highly flexible inasmuch as it could communicate with either Kflex or X2 or v90. Plus, it incorporated itself into the new modems in such a way that upgrading to later, improved, newer releases of v90 versions was a snap. Install a new driver or zap a flash rom; wammo, from a practical point of view, all the same thing.

Suggestion: If you are going to shop for a new v90 modem, make an effort to purchase one that is "already" upgraded to the most recent release of v90. This will save you a lot of time later by eliminating the need to search for new v90 drivers and having to upgrade the modem's internal protocol firmware yourself. This is typically done by a special utility provided by the manufacturer that "flashes" the modems internal EPROM (where the protocol firmware is installed) with the latest release of the v90 standard.

A recent advance in modem design is something called a Software or Win Modem. The upside to these modems are: they are very inexpensive (typically under $20), they perform well, and upgrading is only a matter of getting a copy of the most recent driver. The downside to Software Modems is they are designed to operate exclusively with Windows 95 or later operating systems and require Pretium class CPU's at speeds of 166mhz or faster. This is because the PC's CPU now takes over the function of a UART chip on the modem which is costly and no longer present. Although this design typically adds an additional 5% workload on the PC's CPU, I have noticed no observable degradation in overall performance with Software Modems and therefore find no reasons not to recommend them. NOTE: I fully expect Software Modems to eventually be available for other emerging operating systems such as Linux.

If you need to search for new drivers, here is a site where you can start looking. It covers almost every known manufacturer: www.k56flex.com

Most all modems sold today are Plug and Play types, so I will proceed with this understanding. PnP simply means that the install process should all go rather automatically "IF" certain procedures are followed and "IF" your W9x system is fully functional.

Upgrading:

CAUTION: Before physically handling your modem, its a good idea to be wearing a static ground wrist strap to prevent static electricity from damaging your new modem. Follow all manufacturers recommendations.

Step one, go to Start/Settings/ControlPanel/System/Devices and remove the original Modem entry.
Step two, shut down the computer.
Step three, physically remove the old modem.
Step four, reboot the PC, hopefully noting no errors, then shut down again.
Step five, with power off, install the new modem.
Step six, power on the PC and run Windows. The PnP portion of W9x should sense the new modem and run the Install Wizard which should guide you through the process. Make sure you have the driver floppy disk or CD that came with the new Modem.

If you are installing a new "first time" modem, begin at step Five.

All of the above steps must be followed exactly and presume your PC uses Plug and Play devices throughout. Caveat: If you have installed any non plug and play devices and manually dedicated either com port services and or interrupt services, you are possibly in for a lot of extra work that may be beyond the skills of the average user to rectify.

In this case, one painful option is to remove all non PnP devices and drivers, get your PnP modem working first, then return to re organizing your other devices one by one.

If you were successful in installing your modem, here is a cool online site where you can test it HERE

If you suspect the modem is not behaving correctly you can do some basic testing with any available modem terminal program. If you don't think you have one, you can get a free one from here: www.hilgraeve.com

This and all other terminal programs must be minimally configured or setup to use the same COM port and Interrupt that your modem is set to in order to do the following test.

After the terminal screen opens, try typing the modem attention command "AT" followed by the Enter key. If your modem is set to local echo you should see "AT" appear on the screen. If the letters "AT" do not appear, you should definitely see either a zero "0" or an "OK" appear if the modem is responding. If you do not see the zero or OK reply, the likely hood is that your modem is improperly configured or installed.

If you succeeded in getting the modem to respond try typing "ATH1" and see if you hear the dial tone appear as the modem lifts the receiver off hook. If so, type "ATH0" to hang it back up again.

At this point, and assuming you have the right terminal emulation set (ANSI is standard) you could even call and logon to a BBS or bulletin board. (Yes they still exist). To manually dial your modem using Touch Tone, type "ATDTXXX-XXXX" where the X'es are the number to be dialed.

Solving some modem configuration problems:

All modems are controlled or "set" to certain configurations by electronic commands or "switches" sometimes referred to as modem initialization strings (when several switches are linked together). Some of these commands or switches were discussed in the paragraphs above.

Most modern modems are generally set by the factory to a certain number of preset or default settings that allow the modem to operate in the widest possible PC environments. Occasionally this is not the case and switches must be manually set. The following switches will correct the most common problems users are likely to encounter.

&F reset modem back to its factory defaults
&V1 make modem show its current settings
&D2 allow modem to hang up properly
&C1 allow modem to detect lost carrier
W2 force modem to reply with all CONNECT msg's
M0 Speaker Off (its M zero)
M1 Speaker On until carrier received
M2 Speaker always On
M3 Speaker disabled while dialing and after carrier received
L0 Speaker volume Low (its L zero)
L1 Speaker volume Low (same as L0)
L2 Speaker volume Medium
L3 Speaker volume High


There are literally dozens of highly specialized switches. If you need something special, you should check the manufacturers manual that came with the modem.

More modem info:

Technically, your modem must communicate with your motherboard as well as with another modem on the other end of your phone connection. The speed that the modem talks to the motherboard is called DTE and is typically locked at the highest speed the modem can accommodate. For most 56k modems this lock speed is 115,200 baud. For slower modems it might be 57,600 or even less.

When your modem starts talking to another modem it performs something called a "handshake" wherein the two modems agree to what speed they will talk and with what protocol. This speed, called the DCE or actual modem to modem CONNECT speed should always be lower than the port locked speed or DTE. If your modem fails to pass this CONNECT or DCE speed to Windows, the most likely reason is an out of date modem driver or .INF file.

Windows will default to indicating the DTE speed of 57,600 or 115,200 anytime it fails to receive the correct CONNECT speed from the modem. Sometimes this can be corrected by adding the "W2" switch to the Extra Settings dialog box in the W9x modem setup window.

Here is some other useful information from the original standards that IBM defined for PC's. And, believe it or not, its still somewhat followed today....

COM1 by default uses the port address at 3F8 hex.
COM2 2F8h
COM3 3E8h
COM4 2E8h
COM1 by default uses interrupt service routine 4 (IRQ4)
COM2 IRQ3
COM3 IRQ4
COM4 IRQ3


Com ports above 4 were never used until AT class PC hit the market; however, when made available, they can generally be strapped with any "available" IRQ.

IRQ12 is set aside for PS/2 mice and pointers. IRQ5 and 7 are typically set aside for Printer Ports

Finally, it is also possible to have more than one modem installed in your PC as long as each is assigned its own hardware services, and or, is used under the proper (or non conflicting) circumstances.

Here are more good modem links that may help solve some problems:

Curt's Modem Page www.teleport.com/~curt/modems

ModemHelp www.modemhelp.com/

Finally, another Microsoft built modem diagnostics utility can be obtained directly from them Here

Sorry, I have no direct experience using it.