Curt's High Speed Modem FAQ: v.34, 28.8, 33.6, modem initialization
strings, modem setup, USR, Supra, UARTs, bps communications & comm
overruns, high-speed Trumpet, slip, ppp, & winsock setup, Sportster,
Courier, RPI Rockwell, Zoom, Hayes Microcom. Win95, Windows 95, Curt's
High-Speed Modem FAQ: analog connections, 28800 28,800 33600 33,600 modems.
                                  [Image]

                       Cur t's High Speed Modem Page

                 PC Modem News, FAQs, Files, Tips & Tricks

             Welcome visitor number 354482 (since 22 Jul 95).

    I-Way500 winner -- TheBBSList.Com's Hot Site of the Week -- Best of
                                 Teleport!

                                  [Image]
 (Three judge panel rules Communications Decency Act, which severly limits
         your Internet freedom, unconstitutional. Click for more!)

"If you have a PC, run MS Windows 3.1 or Windows 95, have or are thinking
about getting a 28,800 or 33,600 bps modem, and use or plan to use SLIP or
PPP to access the Internet under Win95 or Win3.x, then this page is for
you."

                             Table of Contents

   * Getting Individual Help                             [Best of Teleport]
   * Introduction
   * Communications Decency Act
   * 28.8/33.6 bps Modems
   * What to Buy/Not Buy
   * Chipsets and Firmware
   * Chipsets and Firmware
   * Analog and Digital                                        [I-Way Logo]
   * RPI Modems and "Software" Modems
   * 56 kbs Modems???
   * Cable Modems
   * 16550 UARTs
   * Bits, Bytes, Baud, and CPS
   * Internal vs External Modems
   * Data Compression and DTE Speed
   * PC Serial Port Hardware Setup
   * Setting Up and Running your Modem Under Win95
   * Windows Comm Settings
   * Trumpet SLIP and PPP settings
   * Trumpet SLIP and PPP settings
   * Running AT Commands within Trumpet Winsock            [WebNow Top 500]
   * Modem Initialization Strings
   * Why is my 28.8 or 33.6 Modem Connecting at 115,200?
   * Improving CONNECT Speed of High Speed Modems
        o Premises Wiring
        o Using a "Teleprotector"
        o Telephone Co. Line Quality
   * Links to Data About 28.8/33.6 Fax-modems
   * Links to Modem Manufacturer's Pages
   * Modem News Conferences
   * Items of Interest about High Speed Modems
   * How an ISP, Like Teleport, will save you $$$
   * Credits, Copyright and Disclaimer
   * My Home Page ...pretty cool -- better visit it.
   * Mark's Auto Page ...What's this got to do with modems? Nothing! But if
     you live near Portland, Ore, and need a car, see my friend Mark's Auto
     Page. Tips, leasing info, and lots of vehicles.

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   * Getting Individual Help: . . . I wish I had time to individually help
     each person who is having problems with their modem or their system,
     but I have lots of demands on my time which limits my ability to
     correspond about specific problems. I welcome mail with comments about
     my page, and of course I do benefit from hearing the specifics about
     modem problems. But if you need help, please try looking around on the
     news conference called comp.dcom.modems for similar problems and
     solutions. If you don't find an answer, then post your own article
     there requesting assistance. When you post, be polite, describe the
     problem and your system setup in enough detail that others can help,
     use a subject line that will catch people's eye, and be prepared to
     recraft your article and repost every few days if you don't attract
     expert help at first.
     [GoTop]  Return to top

   * Introduction: . . . If you have a PC, run MS Windows 3.1 or Windows
     95, have or are thinking about getting a 28,800 or 33,600 (yes, 33,600
     -- more below) bits/second (bps) modem, and use or plan to use SLIP or
     PPP to access the Internet, then this page is for you. While the focus
     here is on 28.8/33.6 bps modems, the information will also be useful
     to those running 14,400 bps modems. This page is geared to tell you in
     general terms the main things you need to know to optimize your system
     for using a high speed modem. If you want more detailed technical data
     than is provided here, check some of the references linked to this
     page.

     The word MODEM is an acronym for MOdulator-DEModulator. Modems accept
     digital data supplied by the local PC, and convert it to a modulated
     analog wave form that can be transmitted over the phone line. And
     conversely, modems also accept a modulated analog wave from the
     telephone line, convert it to a digital form, and pass it on to the
     local PC.

     A 28,800 or 33,600 bps modem can send data over a phone line up to
     fourteen times faster than a 2400 bps modem. Couple this with the
     built-in data compression ability of most high speed modems which will
     compress ordinary text data by about 2:1, and some types of data by up
     to 4:1, and you can see that throughput can be 25 to 50 times greater
     than for a 2400 bps modem. This tremendous increase in speed can
     dramatically decrease your online time and your phone charges, and
     makes it feasible to transfer graphics screens such as WWW pages in
     times acceptable to most users.

     However, these high speed modems can present a challenge to a PC owner
     -- especially for those wanting to run the modem under Windows or
     Windows 95. With improper hardware and software setup, incoming modem
     data can "over-run" the ability of Windows to process it, resulting in
     lost data, retransmission of data, and other problems. Read this page
     to find out how to optimize your system to maximize performance and
     minimize overrun problems.

     Note that even though V.34 is a relatively new protocol, an improved
     V.34 version is now in common use -- the new version keeps the V.34
     name, but adds the speeds of 33.6 Kbps and 31.2 Kbps.

     This page also includes information about how to setup and run your
     modem under Win95. As 32-bit apps become common-place, more and more
     people will be switching to Win95 due to its 32-bit architecture and
     its built-in 32-bit TCP/IP and PPP.
     [GoTop]  Return to top

   * Communications Decency Act: . . . The Internet is the first medium
   * Communications Decency Act: . . . The Internet is the first medium
     that allows anyone with a modem and a PC to publish       [ FREEDOM ]
     world-wide at a nominal cost. But on Feb 1, 1996, the
     U.S. Congress passed the Communications Decency Act (CDA), which
     places constraints on your freedom of speech and public discourse on
     the Internet. On Jun 12, 1996, a panel of three federal judges ruled
     that the CDA is unconstitutional, and enjoined the enforcement of both
     "indecency" and "patent offensiveness" statutes. This ruling paves the
     way for the supreme court to overturn the law.

     Freedom of speech is a cornerstone of the U.S. Constitution, and it is
     the First Amendment of the Bill of Rights. Free speech is critical to
     the success of the Internet, and citizens and industry must continue
     to work together to protect this fundamental right. Philippe Kahn,
     founder of Borland, says "There are no compromises to Freedom of
     expression... The price of our freedom is the burden of having to
     accept the worst in public expression. For he who starts censorship
     will never know where and when to stop". Click here for the latest CDA
     news, and what you can do to help.
     [GoTop]  Return to top

   * 28.8/33.6 kbps Modems: . . . 28.8 or 33.6 kbps modems, under ideal
     phone line conditions, will transmit data at 28,800 or 33,600 bits per
     second, and by using data compression, can achieve throughputs of 2 or
     more times that rate on compressible files.

     An improved version of the V.34 standard has just been finalized which
     adds the optional speeds of 33.6 Kbps and 31.2 Kbps. The speeds are
     optional, enabled at a manufacturer's discretion and negotiated at the
     beginning of a call. AT&T Paradyne, Penril, Zypcom and Motorola were
     among the first selling 33.6, but those were mostly high-end modems.
     USR got the jump on most other manufacturers of consumer-grade modems
     by adding 33.6 capability to their V.34 Courier and part of their
     Sportster lines. Now, MANY other consumer-grade modem manufacturers
     have 33.6. For many people that already have 28.8 modems, there may be
     little reason to run out and get a modem that supports the new
     protocol. To achieve speeds above 28.8 kpbs, the modem on the other
     end must also support the new protocol. That is, you wouldn't be able
     to get a connection above 28.8 kbps unless your Internet Service
     Provider (ISP) and the other places you normally call also have 33.6
     kbps modems. Also, many phone connections simply will not support
     speeds that high -- so if you can't get 28.8 connects now, it is
     doubtful that you would get connects faster than 28.8 with a modem
     that supports 33.6 kbps. More on this topic later.

     The current 28.8 modem "standards" are V.34 and V.FC. The V.FC
     protocol was an interim protocol developed by Rockwell and introduced
     ahead of the V.34 standard being completed in a effort to capture
     market share. V.34 is a more robust protocol, and now most new 28.8
     modems meet the V.34 standard (or both V.34 and V.FC for backward
     compatibility). Almost all current high speed modems implement V.34.
     But you may want to make sure the modem you buy also supports V.FC if
     you communicate with a variety of other modems. Note that the V.34
     standard is in some ways like a tool-box: there are many optional
     parts, and manufacturers can pick and choose which of the options they
     want to include. Cheaper modems generally implement fewer of the
     options, which may limit throughput or flexibility. For example, many
     low-end modems do not support split (asymmetrical) transmit/ receive
     speeds.

     Regarding support and upgrades, note that while the V.34 standard
     continues to mature, you can anticipate many modems available now will
     have firmware upgrades issued as the standard matures and the
     manufacturers shakeout the "bugs" and compatibility problems. If you
     get a cheap, no-name modem, your chances of getting future upgrades or
     other support will probably be slim to none. Most reputable modem
     manufacturers have on-line support in the form of a BBS or better yet
     for us net-heads, a WWW page or FTP site. This page has links to a few
     of these.
     [GoTop]  Return to top

   * What to Buy/Not Buy: . . .So what modem should you buy? Well, there
     are lots of decent brands and models to choose from. While I do not
     recommend specific modems, if you read this page you will get a lot of
     good info that will help you make a wise decision. But here is some
     good general advice -- stay away from el Cheapo bargain basement
     modems -- think about this: 1) Your modem is your primary link to the
     internet, 2) You have a lot of money invested in your system, and 3)
     You are probably paying a substantial annual fee for internet access.
     So saving a few bucks on an bargain basement modem is false economy,
     and will almost always cost you in the long run. If you buy a crummy
     modem, you will most likely experience lots of setup-grief and wasted
     time. Even if the modem seems to be working fine, it may have slow
     through-put. Since everything else in your system is faster than your
     modem, it is the critical path on your net access, and therefore not
     the place to economize. My advice: stay with popular name brand models
     -- this will give you the best chance at support and future firmware
     upgrades, and they hold their value better if you decide to sell and
     upgrade. Look at the company's web site to get an idea of the level of
     their technical support and upgrade policies before you buy. And buy
     from a place that will take the modem back if you find it doesn't work
     for you...it is worth paying a few extra bucks for that. While the
     current crop of no-name 28.8/33.6 modems are generally better than the
     ones available a year ago, it is still a good idea to go with a
     name-brand product from a manufacturer who has a track record for good
     support and upgrades.

     In summary, remember this Forest Gump paraphrase: "Momma always said
     life was like a cheap modem... you never know if you're gonna
     connect..." :-) .
     [GoTop]  Return to top

   * Modem Chipsets and Firmware: . . .Lots of people ask which V.34
     chipsets are used in various modems. Most of the bargain basement
     modems use the Rockwell chipset (a few use AT&T chipsets). These are
     frequently refered to as Glue 'n Go modems -- the manufacturer does
     little more that assemble purchased chipsets on a board. Rockwell
     chipsets are also used on some modems that are NOT Glue 'n Go (Supra,
     Cardinal, Microcom DeskPorte FASTs, others) -- with these, the
     manufacturer has done fairly extensive modifications and extensions to
     the Rockwell control code, and added features (like Supra's split
     transmit/recieve speeds, flash ROM, speed display, Caller ID, etc).
     Most of the higher-end modems use their own chipsets, or higher-end
     sets not made by Rockwell (USR, Multitech, Motorola, AT&T Comspheres,
     Telebit Fastblazers, Penrils, Zypcoms, others).

     So how to you tell what chipset a modem you are considering buying
     has. Frequently it will say on the box or in the product sheet (ie
     "Industry Standary Rockwell Chipset"). If its an internal modem, you
     can just look for names on the bigger chips -- "Rockwell", "AT&T",
     etc. Or you can ask on the news conference comp.dcom.modems.

     Why should you be interested in chipsets? Most experts recommend that
     you get a modem which is similar to the ones you'll most often be
     connecting to. For example, if your ISP has Microcom modems, a good
     quality Rockwell chipset based modem should give good performance
     without having to do any extraordinary setup work-arounds. So in this
     case you would expect a Supra (a good Rockwell based modem) to work
     well, while a cheap AT&T chipset based modem may experience some
     connection problems with the Microcom. This doesn't mean modems with
     different brands of chipsets will not communicate -- it is just a
     possible problem area to be aware of (in my case, I have a USR Courier
     modem which connects with zero problems to my ISP's Microcoms). But
     even if you plan to buy a modem with the same brand of chipset as the
     modem you will most often connect to, I would still be weary of
     el-cheapo Glue 'n Go modems -- you will normally find their quality,
     documentation, and support is lacking.

     Most modem manufacturers put their "control" firmware in ROM, so
     upgrading the control code normally requires replacing a socketed
     chip. Frequently the other part of the firmware, the "datapump" code
     (the code which handles the encoding and decoding of the analog
     signal), is "mask-programmed" onto the datapump chip, which is usually
     soldered to the modem board. This means the datapump code can't be
     upgraded except at the factory. Some manufacturers, like USRobotics,
     place both the control and datapump code in a socketed ROM on some
     models so both can be easily upgraded. Upgrades are even easier if the
     manufacturer places the firmware in "Flash" ROM, which is
     electronically upgradable -- you just download the upgrades from a BBS
     or FTP site. Supra, and most other manufacturers who use Flash ROM,
     only use it for the control portion of their firmware. Some high-end
     modems have both control code and datapump code in Flash ROM -- the
     most popular example of this is the USR Courier. Because the datapump
     code is part of Courier's Flash ROM, conversion of this modem from a
     28.8 modem to a 33.6 modem involves only downloading and running the
     new Flasher program. Converting most modems which have the datapump
     code in firmware would require a factory upgrade -- making this not
     practical in many cases. However, Supra surprised many people by
     announcing that you could flash many of their Supra 288 Data/Fax
     modems to 33.6 (to tell, give the command ATI7 and you should see
     (RC288DPi Rev 05BA) or (RC288DPi Rev 04BC). The 04BC datapump requires
     a chip upgrade, but the 05BA can be flashed to 33.6 -- see the Supra
     WWW site for complete details).

     As the various manufacturers of chipsets and modems evolve their
     firmware, compatability problems diminish and life gets better. I feel
     Supra had a responsible strategy in this regard. Their first 28.8
     modems had flash rom. They knew they would be frequently upgrading
     their firmware, and Supra owners would be able to benefit by getting
     the improved firmware versions from the Supra FTP site with little
     problem. Then, after Supra had stabalized their firmware from
     experience and lots of user feedback, they introduced their non-flash
     SupraExpress model for users looking for a no-frills lower cost
     product.
     [GoTop]  Return to top

   * Analog and Digital: . . .You probably know that modems are analog
     devices. You may not know, however, that almost all calls in US are
     converted to digital at your local phone company office, and stay
     digital until the local loop of the person you call. So what is going
     on is we start with digital data at our computer, convert it to analog
     in our modem, and send it out to the phone system. The phone company
     switches it back to digital and transmits it, then converts it back to
     analog for the local loop at the other end. There, the modem converts
     it from analog back to digital for the remote computer. Eight
     conversions per byte for full-duplex -- when you think about it, it's
     amazing this stuff works at all!

     Analog V.34 modems utilize nearly the full bandwidth of the present
     day phone system (actually, more than the "rated" bandwidth) -- that
     is, 33.6 kbps is pushing the speed limit of the current analog phone
     system. Note that MANY people who have 28.8 or 33.6 kbps modems will
     never achieve connections at those rates due to phone line conditions.
     The next generation phone system will be digital. It will be called
     ISDN, which stands for "Integrated Services Digital Networks". ISDN is
     basically the existing telephone network turned all digital, using
     existing switches and wiring wherever possible. The type of ISDN most
     likely to be used in residential service will support two 64K
     voice/data channels, and one signaling/packet networking channel.
     While ISDN is starting to appear in many parts of the US, its cost
     varies from reasonable to expensive. In many places the evolution to
     ISDN will not be rapid due to the rates most phone companies are
     charging for service, and the amount of customer equipment (including
     your modem) which will require ISDN digital replacements. Watch for
     breaking news on ISDN during 1996 as modem companies announce ISDN
     products, and phone companies install more ISDN facilities. For more
     info, check out c|net's ISDN Modem Review, and Dan Kegel's ISDN Page.

     What this all means is that many of us are going to be using our
     28.8/33.6 modems for quite a while -- so choose wisely when you buy!
     [GoTop]  Return to top

   * RPI Modems and "Software" Modems: . . . RPI modems are inexpensive
     modems which use a special Rockwell chip set that (in most cases)
     implements error correction and data compression in software which
     runs in your PC's CPU instead of within the modem hardware. Althought
     the range of software with built-in support for RPI is quite limited,
     there is a Windows 3.1 driver available, and more recently a Win95
     driver, which is designed to let most comm software work with RPI
     modems when running under Windows. Up until late 1995, RPI modems were
     only 14,400, but as from October 1995 there are now versions of the
     Rockwell V34 Chipsets that use RPI to provide Software Error
     Correction and Data Compression. This is in addition to, or instead
     of, Hardware Error Correction. Check out this excellent reference,
     Psimoon's RPI Information Page, for "The Truth on RPI".

     While the concept of using your PC's CPU to perform compression, error
     control, and other modem functions is reasonable and may be the wave
     of the future (especially as new PC systems continue to increase in
     processing power), RPI earned the bad reputation it has due to past
     limited software support, performance problems, extremely late release
     of Windows drivers, and deceptive packaging which gave little clue to
     purchasers that the modem they were buying was missing hardware error
     correction and data compression. While the current Windows drivers
     make the RPI modems more viable, many people still have problems with
     RPI modems. Because of their poor track record and the dirty packaging
     tricks RPI modem venders played on end users, I recommend NOT
     purchasing any RPI modem.

     If you are looking to buy an inexpensive modem, but wish to avoid RPI,
     look carefully on the box before buying for any hint that a RPI modem
     is inside ("RPI", "Software Error Correction and Data Compression",
     "Error Correction and Data Compression software included", "Fax-Modem
     with Rockwell Modem Technology", "Windows Required"). Some RPI modems
     were packaged so you just can't tell, so it is wise to get the vendor
     to agree to a return if the modem turns out to be RPI, or if you
     experience problems getting it to work (such a return agreement is a
     good thing to get no matter what kind of modem you buy). If you
     currently have an RPI modem, read the RPI FAQ and get the current
     WinRPI drivers at the Rockwell WWW site.

     USR came out with its WinModem recently (which does not use a RPI
     chipset) -- it is a modem that will only function under a Windows
     environment -- as is clearly marked on the packaging -- and performs
     many of its functions in software running in your PC's CPU (some
     people refer to this type of modem as a "software modem"). A year ago
     I would have said to stay away from such a product. But on the robust
     PC systems of today, the WinModem seems to function quite well, and is
     available at attractive prices. Upgrades to these modems will normally
     only require a software update. There are of course risks to buying a
     product that depends on a particular operating system, but if you do
     all of your communications processing under Windows, have a PC that
     has adequate horsepower for your normal processing needs, and you are
     an average to light modem user, then one of these value-priced modems
     could be worth a try.
     [GoTop]  Return to top

   * 56 KBPS Modems over ordinary phone lines? . . . You may have recently
     seen discussions about 56 kbps modems coming out which utilize
     ordinary phone lines. USR and Rockwell have both made announcements of
     coming modems which will allow downloading from your ISP at 56 kbps.
     For this system to work, your ISP will need digital connections to the
     net and special modems -- and of course you will need the a modem
     capable of utilizing this protocol. There is currently no standard for
     this technology -- without a standard, it is likely there will be
     compatibiltiy problems between manuactureres' products, and a battle
     to see who captures the market share (ala VHS vs Beta). Who's going to
     win? Good question -- so far my money is on USR, but only time will
     tell. The 56 kbps transfer rate will only be in the download direction
     (uploads world be at the normal V.34 rates). Right now these 56 kbps
     modems are vaporware. But Rockwell, USR, and other big players are
     actively working to build support and alliances for this technology,
     with some success. An approved standard by the ITU is a long way off,
     but if one of the big players can get a defacto industry standard
     started this technology could move out rapidly, driven by people
     wanting 56 kbps without having to pay the premium price of an ISDN
     line. If some of the big ISP's install the needed equipment at their
     end, other ISPs would need to follow suit to remain competitive. With
     big ISPs such as AT&T, GTE, Sprint, and others already pressing the
     smaller ISPs hard for market share, this could be the beginning of the
     end for many smaller ISPs who cannot afford a major reinvestment in
     equipment. So stay tuned for more information, and look for products
     to start appearing in the first half of 1997. Meanwhile, check out
     "X2" at the USR site, read about K56Plus at the Rockwell site, and
     stop by Motorola's "Tidal Wave" 56K technology upgrade site for more
     info. By the way, USR has a free X2 upgrade deal going if you bought a
     Sportster between 27 Nov 96 and 4 Jan 97, or a Courier by 31 Jan 97.
     [GoTop]  Return to top

   * Cable Modems . . . Over the last couple of years there has been lots
     of talk about cable modems -- modems that would hook to your TV cable,
     and let you get very high speed internet access. Yet, relatively few
     cable companies have actually made cable modems and cable internet
     service available to their customers. Bandwidth problems would
     probably be experienced by most cable companies if they brought cable
     modems into wide use. With a cable modem the extent of your access to
     the internet is decided by your cable company, as of course are your
     service fees. You should contact your cable company to see if they
     have internet service available via cable, and what their prices are
     for their cable modem and their service. Those that I have talked to
     who have cable modems seem very pleased with the service and of course
     the speed. Some have reported quite reasonable prices (less than $30
     per month), while others report higher prices ($60 per month plus
     installation). Keep me posted on what you find -- THANKS.
     [GoTop]  Return to top

   * 16550 UARTs: . . . UART is short for "Universal Asynchronous Receiver-
     Transmitter". All serial devices, such as serial modems, use a UART
     interface chip (or emulate a UART) to communicate with your PC.
     External modems connect to your PC using a serial cable hooked to one
     of your PC's UART-based serial ports, while internal modems have a
     UART-based serial port (or emulator) on-board. It is important that
     you know a little about UARTs in order to avoid problems in setting up
     your system to efficiently use your modem. Basically, UARTs convert
     parallel data from your computer into a serial data stream, and
     vice-versa. Most serial ports that come with PC's (especially
     non-Pentium systems) have a 8250 or a 16450 UART. While these chips
     are capable of passing data at rates much higher than is necessary to
     keep a 28.8/33.6 modem busy, they have only a single character buffer.
     The problem is that on many systems Windows may not be able to fetch
     characters from the UART fast enough to prevent the next incoming
     character from overwriting the single-character buffer, resulting in a
     "comm overrun" or "CRC" error.

     The 16550 UART has a 16 character FIFO (First-In, First-Out) buffer
     and performs flow control -- while the buffer may seem small, it is
     sufficient in a properly setup system. The buffer means that a 16550
     UART doesn't need to "tap Windows on the shoulder" quite so often,
     which helps Windows keep up with the data stream without missing
     incoming characters. However, even with a 16550 UART, an improperly
     setup system will cause characters to be lost, resulting in "CRC" or
     "comm overrun errors".

     Run MSD.EXE, the Microsoft diagnostic program which comes with current
     releases of both DOS and Windows (use the one with the newest file
     date), to see if you have a 16550 UART. EXIT Windows before running,
     as executing MSD in a DOS window can give bogus results. If MSD shows
     you don't have a 16550 variety of UART, you should upgrade your serial
     port hardware. You can buy a new serial card which has a 16550 UART or
     equivalent for about $30, plus or minus. For a little more money, you
     can get a multi-function IO card which includes 1 or 2 serial ports
     with 16550 UARTs or their equivalent (many modern multi-function cards
     use integrated chips that have the UARTs embedded). Be sure to look at
     the specs that come with the card to assure the UARTs are equivalent
     to a 16550. If the docs don't say so, don't believe the salesman! As
     an alternative to buying a new serial card, you may be able to upgrade
     an older serial card pirated from an old PC. If the serial card has a
     socketed 8250 or 16450 UART chip, you can just unplug that chip and
     replace it with a 16550 -- they are pin compatible. You may have a
     little trouble finding one, but a little calling around might save you
     a few bucks. Wolfgang Henke used to sell them for about $10 plus S&H,
     but doesn't list them anymore -- however, an email to him would be
     worth a try. Wolfgang is a modem expert, and is an excellent source
     for modems and all kinds of other comm equipment.

     Internal modems contain a UART, or equivalent, on-board. Some
     manufacturers use actual 16550 UARTs or emulate one. Others use a
     8250, 16450, or equivalent, and add their own buffering system to
     avoid overruns (with the serial port built-in, an internal modem has
     the ability to "know" whether or not the computer has processed the
     last character yet). Generally, no matter what UART is used, an
     internal modem does not exhibit the same sort of overrun problems that
     external modems can when not connected to a serial port which contains
     a 16550. Bottom line: if you have an internal modem from any reputable
     manufacturer, you shouldn't need to worry about what UART is on-board.

     Hayes, and some other vendors, sell Enhanced Serial Ports (ESP). An
     onboard CPU and extra memory for buffering allow these ports to handle
     DTE rates up to 230 kbps without comm overruns. Most owners speak
     highly of these $100 to $150 devices, but some have had problems
     getting ESPs to work with some software or operating systems (OS2, NT,
     Win95). Because a properly configured system containing a 16550 UART
     is more than adequate for almost all real-world conditions involving a
     28.8/33.6 modem, its hard to see where you would benefit from spending
     the extra money for an ESP unless you have some unusual needs. After
     reading about Data Compression and DTE Speed you will understand more
     about the reasons for this .
     [GoTop]  Return to top

   * Bits, Bytes, Baud, CPS: . . . When people talk about modems you hear
     the terms baud, bps (bits per second), bytes, and cps (characters per
     second). Here is a little info to help you keep the terms straight.
     Baud, named after the 19th century French inventor Baudot, originally
     referred to the speed a telegrapher could send Morse Code. It later
     came to mean the number hi/lo shifts made on a line per second. A bit
     is a single binary piece of data which can be represented by a 0 or a
     1. Many people refer to V.34 modems as being 28,800 baud modems. This
     is not correct. Rather than just using simple lo/hi shifts, modern
     high speed modems transmit "symbols", each of which can signify one of
     many bit patterns. For example, V.34 modems us symbols which can
     transmit about 9 bits each, and thus can achieve a data rate of 28,800
     bits per second using a much lower symbol rate of about 3200 symbols
     per second (about the maximum bandwidth capability of today's analog
     phone systems). Even MS Windows and Trumpet lists the port speed
     setings incorrectly as "baud". So remember -- the proper term to use
     when talking about modern high speed modems is bits per second (bps),
     not baud.

     While a normal byte (a "character") contains 8 bits, start and stop
     bits (which are required for an asynchronous data stream) are added by
     the sending serial port's UART and removed by the receiving UART.
     However, with V.42 error control in effect, the start and stop bits
     are stripped away between the two modems -- the data is actually sent
     synchronously, not asynchronously. V.42 also adds and strips out error
     control check bytes for each block of characters sent.

     Based on the above, you may figure you will get a throughput of (28000
     bps) / (8 bits per char) = 3600 cps. However, there is some overhead
     which reduces that a little. All said and done, at 28800 bps, with
     V.42 error control enabled, expect real-world modem pairs to transmit
     data at an average of 3200 to 3300 cps, plus or minus. If data
     compression is enabled, and the data is compressible, the throughput
     will be greater. This will vary depending on the compressibility of
     the data, line quality, and a number of other factors. If you download
     from the Internet, be aware that the servers you are connected to may
     be serving many clients simultaneously, and the "time slice" you get
     may result in data being supplied at a slower rate, or with frequent
     starts and stops. When you connect to a busy server, you will often
     notice that your 28.8 modem isn't getting a chance to earn its keep --
     it will be waiting more than working. :-(
     [GoTop]  Return to top

   * Internal vs External Modems: . . . Internal modems are on a card that
     plugs into your PC's bus, contain their own serial port onboard, and
     use your PC's power supply. External modems are normally
     self-contained in their own case (or may be rack- mounted in
     commercial versions), have a separate power supply, and connect to
     your computer via a serial cable to one of the serial ports on the
     back of your PC.

     Advantages of each:
        o Internal: Easy to install, generally less expensive due to no
          case or power supply, less prone to people messing around with
          them, no cables to get knocked loose, consume no desktop space,
          and you can save $35 or so by not needing to buy a 16550 serial
          card and serial cable.
        o External: Generally incorporate a panel of lights, LEDs, or a LCD
          to display info about the current session, and which can aid in
          problem diagnosis and resolution. Can be powered on and off to
          reset independently from your computer. Normally have an external
          volume control. More easily moved.

     Whether you get an internal or an external modem is largely a matter
     of personal preference. I have used both for years, but tend to favor
     internal modems because they get rid a set of cords, don't collect
     dust, make your PC easier to move or work on, and you don't have to
     concern yourself with UARTs. Many people claim the lights on an
     external modem are critical for trouble shooting, but I've never had
     any trouble with an internal -- you can hear what's going on with the
     speaker, and on many modems you can hear dropped connections (relay
     click). If you still wish your internal modem had indicator lights,
     get ModemSta . This program is the famous "Modem Dashboard" program by
     Ted Johansson -- it displays a replica of modem lights on your screen
     and performs other useful functions. Ted recently announced he is
     discontinuing the shareware version of ModemSta, but may continue
     making it available for a while from his page. He also now has a
     limited-feature freeware version called "ModemSta Lite".

     HOWEVER, some of the new external modems (such as the Supra 28.8)
     feature a speed display that is really cool and perhaps even useful.
     Externals often also have a volume control, which lets you adjust the
     speaker volume very quickly and easily. And an external modem does
     look pretty slick sitting on your desk! :-)
     [GoTop]  Return to top

   * Data Compression and DTE Speed: . . . It is important to understand
     the difference between the "line speed" at which your modem talks to
     another modem (Data Communications Equipment or "DCE speed"), and the
     speed at which your modem communicates with your PC (Data Terminal
     Equipment or "DTE speed"). Modern high speed modems have the ability
     to compress the data they transmit, so you need to feed uncompressed
     data from your PC to your modem at a higher rate than the modem can
     send the compressed data over the phone line. This means you should
     normally set your computer-to-modem DTE speed higher than the maximum
     connect rate you expect your modem to achieve.

     While high speed modems generally won't be able to further compress
     files which are already compressed (such as .zip, .gif, and .jpg
     files), they will compress average text files about 2:1 and sparse
     files such as some spreadsheets and databases up to 4:1. Many people
     recommend setting your DTE rate 4 times higher than your modem speed,
     but unless you are transmitting lots of sparse files, that is normally
     not necessary and can in fact cause overruns and other problems that
     effectively reduce throughput. For 28.8 modems, a good conservative
     setting for the DTE speed in your comm program is 57,600 (38,400 for
     14.4 modems). If you have a robust system, and frequently transmit
     files that can be compressed more than 2:1, you will want to try
     increasing those to 115,200 and 57,600 respectively. However, if you
     do, be sure and check to make sure that comm overruns are not reducing
     your effective throughput.

     The above discussion shows why it doesn't make sense in most
     situations to spend money on an Enhanced Serial Port -- while those
     ports can handle DTE rates of 230 kbps, with most real-world data a
     DTE rate of 57,600 is adequate. Even with sparse data, 115,200 is all
     that is needed. So unless you have some really unusual needs, spend
     your bucks on a better modem rather than an ESP.

     Note -- although the Windows control panel allows you to set COM port
     speeds, virtually all modern comm programs ignore those speed
     settings. So don't worry about the Control Panel speed settings unless
     you use a serial printer or some other brain-dead device. However,
     some of the other settings such as port addresses and IRQs are
     important, so don't indiscriminately make changes to those.
     [GoTop]  Return to top

   * PC Serial Port Hardware Setup: . . . Whether you have an internal or
     an external modem, follow this advice:
        o COM2 is a good port for modems. Most people have a mouse on
          COM1...no need to move that. COM2 has a higher interrupt priority
          than COM1 -- while this is not normally a big factor, it may be a
          factor in marginal systems. Using COM2 instead of COM3 or COM4
          should avoid IRQ conflicts (see below). If you have an internal
          modem set to COM2, be sure to disable any existing COM2 port in
          your system (either in the BIOS Setup, or with a physical
          jumper).
        o Avoid IRQ conflicts -- you normally can't use both COM1 and COM3,
          or COM2 and COM4, at the same time because they share an
          interrupt. If you need to add a "high speed" serial port for your
          modem, try to disable your old COM2 serial port and install the
          new one in its place. If you need more than two serial ports,
          make sure the add-on card you buy allows alternate IRQ settings
          from the traditional IRQ4 and IRQ3 interrupts used by most serial
          ports. Watch out for conflicts with other devices that require
          IRQs. Sound cards, CD-ROM interfaces, and many other cards use
          interrupts which could conflict with the interrupts available on
          an add-on serial card.
        o If you have an external modem, make sure the modem is connected
          to a serial port that has a 16550 UART or equivalent (you don't
          need to worry about UARTs with internal modems because they
          normally contain an adequate UART or a UART emulator on-board).
     [GoTop]  Return to top

   * Windows Comm Settings: . . . When using high speed modems, it is VERY
     important to setup your Windows 3.1x program properly in order to
     avoid comm overruns (i.e., missing incoming data). The multi-tasking
     MS Windows can be a hostile environment for performing high speed
     communications through a serial port. Overruns mean that data is not
     being processed as fast as it is arriving. This results in data is
     being lost, characters being overwritten, and overall communications
     speed is being slowed due to retransmission of data. Minimize problems
     by assuring that the Windows 3.1x SYSTEM.INI file, under the [386Enh]
     section, is properly set up (for Win95, you don't need to worry about
     the settings discussed below). First, make sure that the following two
     lines, if present, read:

             MinTimeSlice=20
             WinTimeSlice=100,50

     These values are the Windows defaults, so the above lines don't need
     to be included. But if they are included, use the above values. A
     smaller value for MinTimeSlice will make multitasking appear smoother,
     but will decrease overall system performance. The WinTimeSlice values
     specify the relative amount of processing time (based on the
     MinTimeSlice setting) given to all Windows applications compared to
     non-Windows applications. Both settings, if improperly set, will cause
     comm problems with high speed modems.

     Also, add the following lines to the [386Enh] section:

           COMnFIFO=1
           COMnBuffer=1024

     Where "n" is your modem comm port -- i.e., COM2FIFO=1 if your modem is
     on Com2. Setting COMnFIFO to 1 enables the FIFO buffer on your 16550
     UART, but doesn't hurt even if you don't have a 16550. Note that
     Windows 3.0 and earlier versions do not support the FIFO feature of
     the 16550 UART -- upgrade to Windows 3.1 or better yet, Windows for
     Work Groups (which has a better architecture for handling serial
     devices than Windows 3.1). The COMnBuffer line specifies the number of
     characters that the device on the corresponding serial port will place
     in the buffer. The Windows default of 128 bytes is not optimum for
     high speed modems. Increasing the buffer to 1024 lets Windows process
     data in more efficient chunks. While recommendations for Com buffer
     settings vary widely, refer to the Navas FAQ for an excellent
     explanation of why 1024 is a good choice.

     Here are some other tips:
        o In Trumpet and other communications programs, don't set the comm
          speed faster than necessary. Setting the comm speed to 57,600 is
          adequate for almost all cases with 28,800 bps modems because very
          little data in the real world will compress more than 2:1
          (exceptions may be databases and spreadsheets). Setting the comm
          speed too high can cause data errors which error correcting
          modems correct by resending, effectively reducing throughput.
        o As mentioned above, don't worry about setting the comm port speed
          in Control Panel -- virtually all comm programs ignore those
          settings.
        o If you run Windows 3.1x (rather than WFWG), it may be desirable
          to replace the default Windows COMM.DRV in SYSTEM.INI with a
          third-part driver. While the Windows 3.1x COMM.DRV is able to
          support 28.8 modems on a fast system, it is not written to take
          best advantage of the FIFO buffer on 16550 UARTs. If you have
          comm overrun problems that you can't otherwise fix, get
          CYBERCOM.ZIP -- it contains cybercom.exe, which will install
          cybercom.drv. The best part is its free (remember -- free is a
          very good price!). NOTE: If you run Windows for Workgroups, DO
          NOT replace COMM.DRV -- WFWG has an improved communications
          architecture which works fine without 3rd party drivers.
        o Watch out for TSR's, certain SCSI drivers, certain memory
          managers, screen savers, and some S3 video cards -- all can cause
          comm problems. A typical problem is some of these disable
          interrupts long enough to cause problems for COM ports and other
          interrupt serviced devices. Try running without these, switch to
          standard VGA mode, etc. to see if you can eliminate problems you
          are having. Always make sure you have the latest drivers and
          programs updates -- many manufacturers have fixed poorly written
          code that was causing comm programs. See the Navas FAQ for more
          details about these and related problems.
        o If you have a 486 or Pentium PC with 16550 UARTs integrated on
          the motherboard, and experience PC lockups when trying to run COM
          applications, the problem may be caused by a problem with a Super
          I/O chip (SMC '665) that many OEMs used to provide serial ports
          on their PCs. This problem typically shows up on PCI-bus-based
          motherboards, but can show up on non-PCI bus PCs as well --
          having the bad chip is all that is needed to cause this problem.
          Microsoft has a software work-around for Windows for Workgroup
          users ONLY -- download the file called WG1001.EXE, which contains
          an updated SERIAL.836 driver with instructions. If you are
          running Windows 3.1x, you need to upgrade to WFWG in order to
          utilize the software work-around.
     [GoTop]  Return to top

   * Trumpet SLIP and PPP Settings: . . . First of all, MAKE SURE you only
     have one copy of winsock.dll on your system. People often end up with
     multiple copies as a result of installing Trumpet updates (i.e., one
     in c:\windows and one in c:\trumpet). Having multiple copies WILL
     cause problems, sometimes even when one is not in your path statement
     -- I know from experience! :-(

     Next, make sure your Trumpet setup values are set properly. People
     recommend any number of different Trumpet settings, but some settings
     will result in excessive data packet fragmentation, or in small
     packets which result in inefficiency due to a low data-to-header
     ratio. These reduce throughput and waste Internet bandwidth. The
     "best" values to use vary depending on your ISP and other factors.
     General guidance is that your MSS/MTU settings should not exceed your
     ISP's settings, and also the smallest MTU of all the machines on the
     path for downloads you request. MTU (the Maximum Transmission Unit) is
     normally set to MSS (the Maximum data Segment Size) plus 40 because
     the size of header added to the packet is usually 40 bytes (20 bytes
     for TCP and 20 bytes for IP). RWIN stands for receive window, and is a
     buffer your PC waits to fill before attending to other TCP/IP
     transactions while you have a download in progress. RWIN needs to be
     large enough to keep the pipe full for downloads, but not so large
     that other threads experience delays due to latency. Most people find
     that RWIN values of 3 to 4 times MSS is a good compromise, but if you
     mostly do large file downloads, then increasing RWIN up to 8 times MSS
     may give better throughput (at the expense of slightly poorer
     performance for other activities you attempt during the file
     transfer). If you set RWIN larger than your ISP has his set, you risk
     experiencing "framing errors". Most authorities recommend the
     following values, but even if ISP recommends different ones, you may
     find these provide good results:

        o For SLIP and PPP:
          - MSS: 536
          - MTU: 576
          - RWIN: 2144 or 4288

     Note that if you have a problem receiving downloads over a particular
     size, it is likely that the your MTU parameter is set too high. The
     MTU is, in simple terms, the "packet size" that your PC can handle
     comfortably. If set too high, incoming packets cannot be read fast
     enough and subsequent packets become destroyed or corrupted. This
     confuses Trumpet, causing it to hang. If you experience this problem,
     and your your MTU is greater than 576, try setting your values as
     shown above.

     Here are two excellent references which will help you troubleshoot and
     tune your Winsock settings:

     o Al's Winsock Tuning FAQ ...exceptional FAQ by Albert P. Belle Isle.
     o Trumpet Winsock Troubleshooting Reference ...comprehensive FAQ by
     Lynn Larrow.

     NOTE: Many people ask whether SLIP (Serial Line Internet Protocol) or
     PPP (Point to Point Protocol) is better. PPP is considered to be the
     better protocol -- it is more robust, and contains error correction
     and other features. The extra coding in PPP makes it marginally
     slower, but not enough to really tell a difference. So which protocol
     should you use? PPP is the serial protocol of the future. However,
     SLIP is more widely installed, is adequate for most applications, and
     is often the only serial protocol available for a specific piece of
     hardware. For now either protocol is just fine for PC Internet
     connections over serial lines, so use whichever one your provider
     suggests. If you have a choice, and the one you are currently using is
     working fine, there is no compelling reason to change. If you want to
     use Win95, choose PPP if your ISP supports it, because Win95 has PPP
     built-in.
     [GoTop]  Return to top

   * Running AT Commands within Trumpet Winsock: There are times when you
     may want to execute one or more "AT" commands while on-line in
     Trumpet. For example, if you have a USR Sportster or Courier, running
     "ATI6" while on line will give you a report on current transmit and
     receive speeds, number of errors that have occurred, total characters
     sent and received, and other data about the current session. Other
     brands of modems frequently have other commands that return connect
     speeds and other data you may want. Many people don't know how to get
     into "command mode" while in Trumpet under Windows. Here is how:

        o Pop up Trumpet and click on Dialler/Manual Login -- this puts you
          in Trumpet's "terminal mode".
        o Type your modem's on-line attention command (usually +++ by
          default).
        o When your modem responds "OK", run ATI6 or any other commands you
          want.
        o When done, type ATO (that's oh, not zero) to put your modem back
          on line, and hit ESC to put Trumpet back on line.

     Note: With some service providers, you may not be able to get PPP
     reactivated when using the above procedure, or the connection may be
     dropped, due to the way the provider has his software setup. Some ISPs
     do this intentionally for security reasons. There is one other
     possible cause for this which may occur if your ISP is inexperienced
     -- your provider may have left his modem's attention command set to
     "+++", which could allow his modem to go into command mode along with
     yours. Whatever the case, if you experience this problem discuss it
     with your ISP -- you will probably either get a fix or an explanation.

     [GoTop]  Return to top

   * Modem Initialization Strings . . . Many people experience problems
     getting or staying connected. Often these problems can be reduced or
     eliminated by using the proper modem initialization string. It seems
     that almost every modem brand and model has its own variation of the
     "Hayes AT Command Set" and "s-register" settings -- there are
     literally hundreds of variations. Detailed discussion of modem
     initialization strings is beyond the scope of this page, but in
     general read your modem documentation carefully, and don't put more
     into the string than is necessary. As an example, with a Supra on a
     PC, the string AT&F2 is an adequate initialization string for many
     users; for a USR modem, AT&F1 is frequently adequate. These two
     examples demonstrate using a "template" -- a pre-defined set of modem
     initialization codes which can be invoked with a single command. Most
     modems contain one or more default templates for different common
     situations, and also let you save your own custom "default" string.
     Many users use an init string that calls up a template, and then
     invokes a few custom commands to tailor the defaults. Read your modem
     docs to see if one of your modem manufacturer's default templates will
     work for you (at least as a starting point). You can also Ask Mr.
     Modem what initialization string he recommends, or check Internet
     Indiana Modem Setup Info.

     Currently there are some compatibility problems between various modem
     brands that can cause connection problems. These compatibility
     problems have been reduced considerably over the last few months as
     the various manufacturers have issued firmware upgrades; the problems
     will continue to diminish as the V.34 standard matures. Meanwhile,
     tweaking your initialization string can often let you work around the
     problems. See The Navas FAQ for lots of Tips about USR modem
     connection problems, some of which are directly or indirectly
     applicable to other modem brands. Also, read news:comp.dcom.modems for
     discussion, tips, and tricks on getting or staying connected.
     [GoTop]  Return to top

   * Why is my 28.8 or 33.6 Modem Connecting at 57,600 or 115,200? . .
     .First of all, your modem is NOT communicating with the remote modem
     at 115,200 bps! What you are seeing is the DTE rate (the speed your PC
     is talking to your modem) instead of the DCE rate (the speed your
     modem is talking to the remote modem). What you want to see is the DCE
     speed -- the communications speed that the two modems negotiate with
     each other when they CONNECT.

     There are two reasons you may be seeing the DTE speed in your modem's
     CONNECT message. The most common one is that your modem is set to
     display the DTE rather than the DCE speed. Some modems, such as Supra,
     display DTE speed by default -- if you don't change the default, you
     will not be seeing the actual CONNECT speed of the two modems. So the
     first thing to do is check your modem's manual and make sure your
     modem is set to display the DCE speed in its "CONNECT" message (for
     example, with a Supra, include "W2" in the init string). The other
     thing that causes display of DTE speed is using Win95 without having
     the proper ".inf" file for your modem. The .inf file lists all the
     CONNECT messages your modem can produce -- if you have an outdated one
     that does not contain the proper messages for your updated modem,
     Win95 can't figure out what is going on with the DCE speed so it
     displays the DTE speed instead. The solution to this problem is to
     visit your modem manufacturer's site and download the most current
     .inf file for your modem, and put it in the Win95 "inf" subdirectory,
     and make Win95 "reinstall" your modem. If you have a no-name modem
     which does not have a web-presence or any other kind of support, it
     may be worth posting a question to the news conference
     "comp.dcom.modems" to see if someone else has an updated .inf file for
     your modem. If that doesn't work, you will either have to live with
     seeing a bogus connect speed under Win95, or you will have to figure
     out how to edit your current .inf file to include the updated info
     needed for your modem (.inf files are ASCII text files).
     [GoTop]  Return to top

   * How to improve the Connect speed of 28800 modems . . . If you rarely
     get 26.4 kbps or 28.8 connects, the reason is almost always a result
     of phone line quality. 28.8/33.6 modems are pushing the limits of
     today's telephone system. Getting 28,800 bps connections requires
     pristine telephone line conditions end-to-end. The following three
     paragraphs, which are from a paper entitled Of Line noise, The Phone
     Company, and Your Modem by Patrick Moore, Supra Corp., explain this in
     more detail:

       -  Repeatable results with V.FC/V.34 modems on real-world phone
          lines are sometimes difficult to obtain.  Unlike V32.bis modems,
          V.FC/V.34 modems will actually modify their data coding (symbol
          rate) and transmit levels during the connect phase.  Very minor
          differences in the phone line can lead to quite different results.

       -  A 28.8K connection on some real-world lines may not occur very
          often, if it occurs at all.  Preliminary testing in the lab
          indicates that "normal" phone line attenuation makes a 28.8K
          connection difficult even in the absence of line noise.  This is
          not surprising considering that the V.FC & V.34 coding schemes are
          relying on the bandwidth of the phone system being greater than
          what is actually available in some areas.  Very high-speed
          connections assume that there is a substantial amount of digital
          technology in the system (thereby normally increasing the usable
          bandwidth).  Some users are going to find that their local phone
          system effectively limits them to 16.8K or 19.2K.

       -  Both the originating and the answering modem are adjusting to
          their line conditions during the connect phase.  The fact that
          a connection to a given modem at a given location occurs at a
          lower rate (19.2k for example) may have nothing to do with the
          modem the call is placed with, or the location it is placed from,
          as the modem on the other end may be adjusting the baud rate down.

     For the above reasons, many people will never see 28.8 or even 26.4
     CONNECTS with their 28.8 modem. The easiest way to find out if its
     your phone line or your modem is to find someone who usually gets 26.4
     or 28.8 connects, and try your modem on her system, or his modem on
     your system. You will most likely find that the problem at your end is
     phone-line related.

     The part of the telephone system which you may be most able to improve
     is your telephone premises wiring. If you rarely get 28.8 or 26.4
     connects, try the following:

        o Premises Wiring . . . Often faulty premises wiring, bad phone
          jacks and plugs, cheap phones, old/antique phones, or too many
          phones or other devices cause problems. Here is how to determine
          if your premises wiring or equipment is affecting your CONNECT
          quality. Find the telco wiring block where all your premises
          wiring connects -- it will usually be outside or inside of your
          house near where the phone line comes in. Look at the interior
          wiring. The best wiring is "twisted pair". Most older,
          non-twisted pair wiring consists of four wires in a single
          jacket. The individual wires have solid color insulation (green,
          red, yellow and black -- but only the green and red wires are
          normally used on a single-line system). Twisted pair wiring
          consists of matched pairs of wires, normally 2 or 3 pairs in a
          single jacket. The two wires in each pair are twisted around each
          other in a gentle spiral. Of each pair, one wire has a colored
          insulation with a white stripe, and its mate is white with a
          matching colored stripe (i.e. white with blue stripe and blue
          with white stripe).

          If you have non-twisted pair wiring, you should consider
          replacing it. But whether you have twisted pair or not, you may
          want to try this experiment. Run a good quality twisted pair
          phone cable directly between the block and the phone jack that
          serves your modem, routing so as to avoid other electrical wiring
          and devices -- and then disconnect all other premises wiring from
          the telco block. If this gives you faster connects, then your
          premises wiring or your phone equipment is causing you trouble.
          Reconnect wiring and phone devices incrementally while retrying
          the modem to see if you can find the culprit. Examine each plug
          and jack, and reseat each several times. Where visible, inspect
          the routing of the phone wiring to assure it steers clear of
          other wiring and electrical devices. If you find some of your
          equipment or premises wiring is contributing to the problem, the
          recommended solution is to replace or eliminate the equipment
          and/or wiring. However, read on for one alternative solution.
     [GoTop]  Return to top

        o Using a "Teleprotector" . . . There is one other solution that I
          have used to eliminate premises problems without replacing or
          eliminating premises wiring or equipment. I have an antique pay
          phone which was causing a problem, but I did not want to
          eliminate that treasure from my system. I ran a new, dedicated
          line from the telco block to my modem jack. Then I bought a $10
          device from Radio Shack called a "Teleprotector" (Cat. No.
          43-107). The Teleprotector is designed to protect fax and data
          transmissions from interruptions, and to shut-off answering
          machines when you lift an extension. The device is a small cube
          with a phone jack on one side and a short phone cord with phone
          plug coming out of the other side. When installed in a phone
          line, the Teleprotector disconnects the phone line downstream of
          itself when any upstream device is off-hook.

          Here is how I used the device: I marked the cord side of the cube
          "telco" and the jack side "phones". I inserted the plug-end of
          the line coming out of the Teleprotector into the jack on the
          other side of the Teleprotector. Then I cut the resulting cord
          loop in half, and stripped the red and green wires at the cut
          ends -- this resulted in the Teleprotector having stripped red
          and green wires sticking out both sides (ignore the
          Teleprotector's yellow and black wires). Next, I removed all
          premises wiring from the telco block except for the new line
          going to my modem. I connected the Teleprotector's red and green
          wires on the side marked "telco" to the telco block, and
          connected the red and green wires coming out the other side to
          all of the premises wiring I had disconnected. NOTE: As mentioned
          above, most residential phone systems which use non-twisted pair
          wire only use the green and red wires -- you can ignore the black
          and yellow wires (just leave them unconnected). Here is a
          schematic:

                             Telco Block
          Incoming             +-----+     Radio Shack
            Telco   >============o-o |   "Teleprotector"
            Line               |     |       +---+
                               | o-o=========|   |=======> To all premises
                               +--\\-+       +---+           phone devices
                                   \\                        except modem
                                    \\
                                     ``==================> Dedicated line
                                                             to modem

          DONE! Now, whenever my modem has the line, all other phone wiring
          and devices in the house are switched off-line by the
          Teleprotector. My average connect rate used to be 24 kbps -- now
          it is extremely rare that I get a less-than a 28.8 kbps CONNECT.
          Another benefit -- now all of the other phones in the house are
          dead whenever my modem has the line, so if anyone lifts a phone
          it doesn't mess up my data connection. Lots of benefits from a
          $10 expenditure!
     [GoTop]  Return to top

        o Telephone Co. Line Quality . . . If you determine that your
          premises wiring is not causing problems, and you still get low
          connect speeds, you can try a few other things like calling a
          known quiet number and listening carefully -- if you hear
          hissing, humming, a radio station or other background voices, you
          have a line problem (you may have a line problem even if the line
          sounds quiet). Reporting noisy conditions will probably be
          sufficient to get the phone company to look into the "problem".
          You may be able to get them to test and improve your line, but be
          aware that all they guarantee to provide is a line meeting voice
          quality standards, and also they may want to charge you for the
          testing if they find no line problem. So you telling them your
          modem can't get 28.8 connections probably won't motivate them.
          However, it has been reported that the phone company will
          generally be responsive to fax problems, so report those if you
          have them. Your connect speeds will frequently be lower when you
          are distant from your telephone exchange , and when your call
          must pass through more than one exchange. See the The Navas FAQ
          for a more detailed discussion about line problems.
     [GoTop]  Return to top

   * Links to Data Sources on 28.8/33.6 fax-modems:
        o The Navas 28800 Modem FAQ ...very comprehensive, with special
          emphasis on USR ...an excellent resource!
        o Data Comm FAQ, Win Ver ...good high speed modem page -- check it
          out.
        o V.34 Modems ...Khu Yi Ming's modem recommendations.
        o Everything You Ever Wanted To Know About Modems But Were Afraid
          To Ask ...Rosenet's modem pages.
        o "V34 Technology" ...Black Box Corp's info page on V.34
          technology.
        o Understanding Comm Port Overruns ...good paper by Dave Houston.
        o Microsoft Knowledge Base ...search for word "modem" plus other
          keywords.
        o Midcom's "Industry Links" ...a page of MANY excellent telephony
          links.
        o Internet Indiana Modem Setup Info ..."A great place to find those
          funny little modem strings."
        o AccessOne Modem Init Strings ...Init strings for MANY modems.
        o More Modem Init Strings: Strings I, Strings II, and Strings III
          ...By the time you get here, you may no longer need these! :)
        o "Connecting Minds" FAQs ...several informative comm FAQs.
        o Wolfgang's Modem Archives ...Modem manuals and other files.
        o Modem.Com Reference Site ...good, but very basic, modem term
          glossary.
        o FAX Facts Part 1 and FAX Facts Part 2 ...just the FAX madam!
        o Wolfgang Product & Price List ...specializes in modems and comm
          products.
        o International Telecommunications Union ...the people who set the
          standards!
        o Modem Basics & Setup ...tech paper -- some good data.
        o Modem Protocol Overview ...tech paper; OK overview.
        o Joy of Telecomputing ...from a book -- older, but pretty good.
        o " License to Speed" ...Computer Shopper modem review -- see note
          below.

     NOTE: There has been much discussion on the conferences about magazine
     reviews such as the Computer Shopper article above. Their tests give
     some useful data, but miss much of the real world stuff. Examples --
     Sportster Spiraling Death Syndrome (now fixed), Practical Peripherals
     and Hayes in chapter 11, etc. I would not base a buying decision
     solely on this or other magazine reviews.

     If you have other links which should be listed here, or find errors or
     outdated links in the above, please mail them to me -- thanks!
     [GoTop]  Return to top

   * Links to Modem and Comm Product Manufacturer's Pages:
        o Aceex Modems ..."in search of innovation".
        o AcerOpen Modems ...Acer Computer's modem page.
        o AMQUEST Corporation ...the home of V.34 230k HyperModems.
        o Apache Modems ..."packed with useful features".
        o Archtek Telecom ...Smartlink Modems.
        o AT&T Paradyne Commercial Modems ...AT&T no longer sells consumer
          modems.
        o Best Data Products ...Best Data Modems Page.
        o Boca on Line ...Boca Research's Home Page.
        o Byte Runner Technologies ...High-speed 16550 & 16650 serial I/O
          cards.
        o Cardinal Modems ...Cardinal's new, and nearly content-free, web
          page ;-(
        o Unofficial Cardinal Page ...Latest flashers, good info.
        o Compaq's Comm Products Page ...Compaq PCMCIA modems.
        o Creative Labs ...Modem Blaster and Phone Blaster modems.
        o DynaLink Modems of Australia ...28.8/33.6 USR compatable modems.
        o E-Tech Web Page ...E-Tech Modems & ISDN Products.
        o Eiger Labs Game Modem ...14.4 DSVD Game Modem w/ Simultaneous
          Voice.
        o Empower Labs ...PC Card Modems.
        o Global Village ...homepage of Global Village.
        o Hayes Microcomputer Products ...Hayes' Home Page.
        o Logicode Technology ...Data/Fax modems and more.
        o Megahertz ...The Mobile Connectivity Company.
        o Microcom ...Microcom's Home Page.
        o Microfax of Australia ...Miniature 28.8 fax/data modems work even
          when your PC is off & print from their own parallel port. Cool.
        o Motorola Modem Problem ..Motorola Power & Lifestyle problem &
          fix.
        o Multi-Tech Home Page ...Multi-Tech, a high-end American-made
          modem.
        o MWave-based modems ...There is no official MWave page, but this
          is a mailing list for MWave owners.
        o NetComm Limited ...Australian manufacture of PC comm products.
        o Newcom modems ....Rockwell chip set modems from NewCom, Inc.
        o PCtel HSP Modems ...Replaces the Modem Data Pump, Controller and
          UART with drivers running on your PC.
        o Penril Datability Networks ...Professional Modems for Corporate
          Use.
        o Philips Solutions Modems ...Big in Europe, not much USA modem
          presence yet.
        o Phylon Communications ...software oriented data communication
          technology.
        o Practical Peripherals ...PP's Web Site.
        o SatisFAXtion FAX Modems ...WildCard Technologies (formerly
          PureData) offers business FAX/data solutions.
        o Racal Datacom ...Racal's data products home page.
        o Reveal Computer Products, Inc. ...Reveal modems and other PC
          products.
        o Rockwell's Baudman ...talk to Baudman with the Baud-A-Cator!
        o Rockwell Modem Systems ...Rockwell's modem home page.
        o Supra (Diamond) Modems ...now part of Diamond MultiMedia.
        o Supra FTP Site ...Flashers, manuals.
        o Telebit Corporation ...Telebit's homepage.
        o TriTech MicroElectronics Intl. ...maker of CODECs that support
          ASVD/DSVD/V.34.
        o USRobotics WWW Site ...General USR Product Line plus Files.
        o WiseCom, Inc ...We are probably inside your PC!
        o Xircom ...Specializing in mobile solutions.
        o Zoltrix Modems ...New, and under construction.
        o Zoom Telephonics ...Zoom Modem homepage.
        o ZyXEL Modems ...ZyXEL's Home Page

     If you have other links which should be listed here, or find errors in
     the above, mail them to me.
     [GoTop]  Return to top

   * Modem news conferences:
        o comp.dcom.modems -- modems & comm software.
        o comp.sys.ibm.pc.hardware.comm -- comm hardware.
        o misc.forsale.computers.modems. -- forsale and wanted.
     [GoTop]  Return to top

   * Modem Items of Interest

        o The 33.6 V.34 Standard is now Official: . . . A new "33.6"
          version of V.34 is now approved by the ITU-T. In its original
          form, V.34 defined speed switching among the suite of speeds
          between 28.8 Kbps and 2400 bps -- the new version of V.34 adds
          speeds of 33.6 Kbps and 31.2 Kbps. The speeds are optional,
          enabled at a manufacturer's discretion and negotiated at the
          beginning of a call.

        o Courier FLASH ROM Updates: . . . USR released a 33.6 kbps FLASH
          ROM upgrade for the US/Canadian version of their Courier 28.8
          modems in Jul 95, has updated it several times since, and the
          current US/Canadian version is dated April 29, 1996. The SDL.EXE
          flash programs for all Couriers can be downloaded (including the
          "MDMUSRCR.INF" file if you use Win95) from the USR FTP Site, DL05
          directory, or from the USR WWW Page. In Feburary USR removed the
          US/Canadian version SDL flash program from their sites and bbs
          due to "export restrictions", but it is now back on line. Another
          way to get the SDL.EXE file is by calling USR's Courier
          1-800-550-7800 support number. By the way, the updates include
          two significant new features -- Caller ID and Distinctive Ring.
          The SDL.EXE file is self-extracting. Be sure to totally EXIT
          Windows before running the new flasher, and its also not a bad
          idea to unplug the phone line from the modem.

          In Oct 95 USR included this new 33.6 kbps V.34 protocol in the
          Sportster line of V.34 modems, allowing the Sporster to achieve
          speeds up to 33.6 kbps when communicating with another modem
          which supports the new V.34 protocol. USR says their 33.6
          software also implemented improvements which consistently allow
          connects of 2400 to 4800 bps faster than older versions. Be sure
          that the box indicates the modem supports 33.6, and also shows
          the modem as "Plug and Play".

          An upgrade ROM chip replacement containing the 33.6 software is
          available for owners of 28.8 V.34 Sportsters. The upgrade chip
          cost is $25 plus shipping -- contact USR customer support at
          847-982-5151 to order.

        o Supra Items: . . . Until recently Supra was an Oregon based
          company, but in 1995 was aquired by Diamond MultiMedia. Visit the
          Diamond MultiMedia page for the latest flash updates and drives
          from their very well organized site. Do an ati3 command from your
          terminal program to see which ROM version you have, and download
          a new flash if yours is not the latest. By the way, the latest
          Supra flagship modem series is the SupraSonic, which features an
          LCD display of speed and modem activity, Flash ROM, Caller ID,
          voice mail capabilities, nonvolatile memory to store user
          configurations, and a headset for hands-free phone calls -- all
          is a compact form factor.

        o USR Sportster 28.8 Spiraling Death Fix: . . .While this is not
          new news, it is important if you own an early USR Sportster V.34
          modem. USR issued a ROM upgrade dated 4/18/95 which fixs the
          "Spiraling Death Syndrome", which is a declining connect speed
          believed to be caused by subtle changes due to thermal drift in
          modem components such as the transformer. Several manufacturers
          probably had similar problems, but USR got the bad press. The ROM
          is free to Sporster V.34 owners. Check your current ROM date with
          an ati7 command, and if you do not have a ROM dated 4/95 or newer
          (US & Canada; other countries may have different dates), you need
          either this free upgrade, or the 33.6 kbps V.34 $25 ROM upgrade
          mentioned above. If you want to get the free ROM, I suggest you
          order from the USR BBS -- have your serial number handy, use your
          modem and comm program to call 1-847-982-5092, and simply type
          "SPV34" from the main menu and then follow the directions. If you
          got your 28.8 Sportster as part of an OEM computer package and
          have trouble inputting your serial number on USR's bulletin board
          when trying to get the spv34 upgrade chip, you need to contact
          USR customer service -- call 847-982-5151 and prompt for
          Technical Support.

     [GoTop]  Return to top

   * How an ISP, like Teleport, will save you $$$: . . . Compared to a
     service like AOL, using an independent Internet Service Provider can
     save you major bucks on Internet access. Teleport, my ISP, is based in
     Portland Oregon and serves several cities in Oregon and southern
     Washington. Their flat monthly rate for a large block of online time
     really frees me to enjoy using my 28.8 modem without worrying about a
     killer-bill at the end of the month.

                 [TELEPORT Logo] helps make this page possible.

   * Credits, Copyright and Disclaimer: . . . I have assembled this page
     primarily from information collected from reading thousands of posts
     on the news conference comp.dcom.modems, from numerous FAQs and modem
     info pages on the net, and from corresponding with a number of
     individuals. I am not a real modem guru . . . I'm just a collector of
     data who has had a fascination with modems ever since I got my first
     one in 1984. I wish to give special recognition and credit to John
     Navas, a true modem expert who's constant contributions on
     comp.dcom.modems and through his exceptional and comprehensive web
     page, " The Navas 28800 Modem FAQ", have contributed immeasurably to
     the web community. I also need to thank Teleport, my ISP, for
     tolerating the traffic this page sometimes experiences.

     This page Copyright (C) 1995, 1996, 1997 by Curt. All Rights Reserved.
     Trademarks belong to their respective owners. You may download one
     copy of the information found on these pages for your personal,
     non-commercial internal use only. You may not modify the materials or
     use them for any commercial purpose or any public display, or remove
     this copyright or other proprietary notices contained herein, or
     transfer the materials to another person. No mirroring of this site is
     allowed. A link to this page may be added to your pages, but if you do
     so please do it in a way that will avoid attracting merely the curious
     (in order to minimize bandwidth), and please EMail me with the URL of
     your page. Contact me with requests for a license for any other use of
     these materials.

     I have no financial associations with any modem manufacturer, nor do I
     endorse any particular manufacturer's modems. I have provided these
     pages purely as a volunteer effort, and their content is intended for
     general information purposes only. Use the information from these
     pages at your own risk, as I make no claim to its completeness or
     accuracy, nor will I be responsible for any subsequent problems you or
     others may encounter from its use. Sorry about including this somewhat
     harsh sounding disclaimer, but it turns out that without such words
     numerous others have been sued for trying to provide free help via the
     Internet.
     [GoTop]  Return to top

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Please mail me any new modem- related links you would like to see here or
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