Classic Computer Magazine Archive COMPUTE! ISSUE 152 / MAY 1993 / PAGE 66

commands, the commands that tell the modem what to do (such as the command
by Rosalind Resnick

In the beginning, modems were slow but steady, the Volkswagens of the computer world.

Simple devices that converted the digital signals from your computer to analog signals capable of traversing the telephone net, early modems performed the basic tasks of transferring files and dialing up online services in a plodding but workmanlike way. If you wanted data compression, error correction, flow control, or any other bells and whistles that might make your data go faster, you had to look to your communications software. As a result, most early modems chugged along at the snaillike pace of 300 bits per second.

For a while, 1200 bps was the standard. Just a few years ago, modems that transferred files at 2400 bits per second became the mainstay of the personal computing world.

Not any more. Thanks to computer users' clamor for faster and less expensive downloads and file transfers, modem manufacturers have been slashing their prices. While some highspeed (V.32bis) modems still cost $500 or more, you can now pick up a reliable one with all the desirable features for under $200. In fact, the price differential between a V.32bis (14,400 bps) modem and a V.32 (9600 bps) modem has shrunk to less than $100.

Dataquest, the San Jose, California, market research firm, says it's only a matter of time before high-speed modems take over the marketplace, making today's 2400-bps modems virtually obsolete. The reasons: the need to transfer large graphics and database files, remote file server of LAN-to-LAN connections, and general sensitivity to connectime charges.

Here's how Dataquest sees things shaping up.

Back in 1987, 716,400 of the modems on the market were 2400-bps modems; only 20,000 were capable of transmitting data at a rate as high as 9600 bps. But the 2400-bps standard couldn't hold its ground for long. Last year (1992), 2400-bps modems peaked at 950,000 units, while sales of 9600-bps modems rose to 400,000 units and sales of 14,400-bps modems, introduced in 1991, more than doubled to 220,000.

By 1996, Dataquest predicts, the modem--not even on the market today--will account for 350,000 units sold with 9600-bps and 14,400-bps modems chalking up a total of 750,000 units sold. By contrast, sales of 2400-bps modems are expected to sink to 480,000.

"The marketplace has possessed a voracious appetite for higher-transmission-rate modems," says analyst Joe Noel, "and Dataquest does not anticipate this changing."

Today's modems are light-years ahead of their predecessors of a decade ago. Swift, smart, and powerful, the new breed of turbocharged modem is loaded with cutting-edge features capable of speeding your data across the country in the blink of an eye--as fast as 57,600 bps--saving you vast amounts of time and money.

Consider: With a 14,400-bps modem, the fastest one of the market today, it's now possible to send a 1MB file from Los Angeles to Boston in 3.05 minutes for just $0.73; sending the same file the same distance at 2400 bps would take 72.82 minutes and cost $17.48. At 9600 bps, the fastest speed available on a major online service, you can download a 1MB file from CompuServe in only 17 minutes for $6.46--less than half the $14.50 you'd pay to download the same file at 2400 bps and a fraction of the 68 minutes you'd have to tie up your computer.

And there's a bonus: Virtually all of today's high-speed modems are fax/data modems. This means there's no longer any need to print out a hard copy of your document and stuff it into your fax machine--or drive over to your neighborhood copy shot and pay exorbitant prices. You simply press a hot key, and your fax transmission is on its way.

Best of all, the new modems are relatively inexpensive. For example, U.S. Robotics offers a 14,400-bps fax/data modem for as little as $499 and AT&T Paradyne's DataPort internal 14,400-bps fax/data modem lists for $505 (at the time of this writing, the internal and external DataPorts are on sale for $399 and $439, respectively). Street prices for these products are even less, and competition is driving prices lower virtually every day. Just two years ago, modems like these cost $1,000 or more. Be sure to shop around for the best price before you buy a highspeed fax/data modem.

Ah, but just like those sexy little Ferraris that burn up the tracks on their good days but seem to spend most of their time in the shop, today's high-speed modems are riddled with technical glitches that can sap their power, at times forcing them down to a speed as slow as 1200 bps, and at other times preventing them from functioning at all.

The reasons are numerous: everything from the inevitable hardware and software incompatibilities to overtaxed communications ports and busy networks.

The glitches result in modems that can't talk to other modems, modems with fax capability that won't send faxes unless you reboot your computer, data modems that can't upload files to a bulletin board, and front-end programs that won't let you go online unless you first shut off all of your modem's special features.

In short, these high-speed modems are creating a veritable Tower of Babel that leaves many home computer users, even those who are knowledgeable about computers, frustrated and confused.

CompuServe member Steve Ringley, an electronics technician who works for the Ohio National Guard, bought a high-speed modem in October to help cut his long-distance phone bills. Because Ringley lives in McConnelsville, a small town about 100 miles southeast of Columbus, there aren't any local access numbers he can dial to log on to his favorite online services.

The new modem managed a connection to CompuServe, Ringley recalls, but wouldn't connect with two other popular services, Genie and America Online. Finally, after numerous calls to technical support staffers and hours of trial and error of his own, Ringley hit upon some modem initialization strings that worked.

"The lack of standardization is the real culprit," Ringley says. "The modems need to figure out what language they're going to use to negotiate with one another."

Asked about the problems, the modem manufacturers and the online services readily acknowledge the trouble but disagree on who's to blame.

"It takes two to tango," says Paul Hansen, vice president of technology and marketing services at Practical Peripherals, a leading manufacturer of high-speed modems. "There is no possible way, with all of the backward compatibility that the marketplace demands, to cover every sort of thing. Why should we as a modem manufacturer do what the software people should be doing?"

The online services, for their part, say they'd like to see the manufacturers get their act together. Les Briney, Prodigy's director of development, says the service offers roughly 35 different modem initialization strings in a downloadable text file and keeps adding new ones every day to keep up with the hundreds of different high-speed modems as they come into the marketplace.

"The problem," Briney says, "is that no two modem vendors have identical modems. The standards are not as strong as they used to be."

Making Peace

If you can't get your modem up and running, it doesn't really make much difference who's to blame. Here's a quick guide to some of the common problems involving high-speed modems, along with some practical solutions suggested by computer users and modem experts.

Problem: With my old 2400-bps modem, I had no problem dialing up my favorite online service. With my new high-speed modem, all I get are error messages.

Solution: If your online service is Prodigy or America Online, there's a reason for that. Both services use proprietary front-end programs developed back in the days when modems were a lot less powerful than they are now. To speed data flow, the two companies built things like data compression and error correction into the software itself. Unfortunately, even when you dial up an online service with a smart modem that has all the latest features, the software still wants to take control.

Change your modem initialization string (the set of commands that begins with AT) to turn off your modem's data compression, error correction, flow control, and other special features. This way, your front-end software will be able to call the shots, letting you dial up and log on with no problem.

Unless you enjoy reading modem manuals (and have the technical savvy to make sense of them), the fastest way to find an initialization string that works with your modem is to call the technical support department of the company that manufactured your modem or the online service you're trying to reach.

Problem: I've changed my modem initialization string, but I keep getting error messages anyway.

Solution: Maybe it's a hardware problem. Before two modems can talk, they must first shake hands, deciding which signaling, error-correction, and data-compression protocols to use in their conversation. However, each modem manufacturer uses its own slightly different method for conducting the protocol handshake. Some even use proprietary protocols that aren't compatible with those of other modem vendors.

To find out if you have a hardware compatibility problem, call the technical support staff at your online service and explain exactly what kind of modem you have. Unfortunately, some of the earlier high-speed modems, such as the V.29 series, aren't supported by online services such as Prodigy. If you have one of these earlier models, you may have to make a choice between logging on to your favorite online service or scrapping your old modem and buying a new one.

Problem: Most of the time, my high-speed modem lets me go online at 9600 bps, but other times when I log on, communication is really slow.

Solution: The problem may be the communications network. If lots of people log on at the same time, the network may slow to a crawl-the same way it takes twice as long to drive home from your office during rush hour. That's why it makes sense to log on early in the morning or late at night when CompuServe and the other services aren't so busy.

Problem: When I try to use the modem, my computer locks up and I have to turn off the computer and reboot it.

Solution: The problem may be an interrupt conflict on your serial port, especially if you've already installed a mouse, an optical scanner, a tape backup, or other serial devices in your PC. Because of the way IBM originally designed the PC way back in 1981, communications ports 1 and 3. use interrupt 4 and communications ports 2 and 4 use interrupt 3. That's why, if you assign both a mouse and a modem to COM1, you're going to have to open up your computer and reset the DIP switch on your modem. Check your modem manual for instructions.

Problem: With my high-speed modem, I keep losing data when I try to transfer files with my Windows-based communications program.

Solution: Maybe it's your UART (Universal Asynchronous Receiver/Transmitter) chips, the chips that control the serial port of all personal computers. During modem communications, your computer's UART and the CPU transfer large amounts of data. When you run your communications program through a multitasking environment such as Windows, DESQview, or OS/2, especially at high speeds, the CPU can't juggle it all and bits of data start falling out along the way.

To fix this problem, you may need to invest in a new piece of hardware. If your computer has an 8250 UART, try replacing it with a 16550A UART that creates a buffer stack that allows the UART to save any incoming data while waiting for the CPU to catch up. Another option is Hayes's ESP Communications Accelerator for Windows, an add-on serial card with a dedicated coprocessor capable of supporting data transfers as fast as 57,600 bps.

Problem: The communications program I've been using for years won't run my new modem at its highest speeds.

Solution: Much of the communications software that came out in the late 1980s won't support modem speeds faster than 9600 bps. You'll need to buy a new program (or an upgrade to your old one) that lets you dial up at 14,400 bps and higher. It's also important to get a program that can take advantage of the 16550A UART described above.

Modem Wars

Remember when Hayes-compatible sounded like modem's first name? Most modems continue to be Hayes compatible, but there's been trouble in modemland. The fallout is incompatibility, consumer confusion, and bad blood by the gallon.

Unless you are an industry insider, you probably are unaware that telecommunications has been mired in a legal morass over the past half decade. The morass was created by a battle that tested the rights of the creators of,intellectual property to protect that property even as the rest of the industry tried to make that property a standard. It was a situation simular to the one Lotus created when it sought to stop the publishers of 1-2-3 look-alikes by bringing lawsuits against them, but with important differences. Hayes, the creator of the industry-standard escape sequence used by most modems, was willing to share its property through licenses, and it found itself the target of lawsuits rather than the instigator.

What exactly is an escape sequence? The escape sequence tells the modem to switch from data mode to command mode. In data mode, your modem is sending information to the receiving modem, and in command mode it's ready to receive AT commands, the commands that tell the modem what to do (such as the command ATH, which tells your modem to hang up) or configure the modem. The guard time mechanism prevents the modem from going into command mode unless there's a period of silence before and after the escape sequence. The escape sequence consists of a period of silence, three plus signs (+), and then another period of silence. The purpose of the guard time mechanism is to ensure that if you're sending a file that happens to contain a series of three plus signs in a row, your modem won't accidentally go into command mode and wait for further instructions.

To make sense of the conflict, here is the recent history of telecommunications in brief. In June 1981, Hayes Microcomputer Products filed for a patent for its escape sequence and guard time mechanism. This patent was granted in October 1985. A year later, Hayes offered to license the technology to other makers of modems. Within a month a consortium of modem manufacturers was formed (called the Modem Patent Defense Group), and two of the members (U.S. Robotics and Prometheus Products) brought suit against Hayes, challenging its patent. Hayes countersued. Microcom, Multi-tech, and Ven-Tel sued Hayes. Hayes sued Everex and Omnitel for patent infringement. Microcom and U.S. Robotics settled out of court and agreed to license the patent. Three of those companies-Everex, Ven-Tel, and Omnitel-ended up in court, where the Hayes patent was upheld. All of the remaining lawsuits were either settled out of court or adjudicated in Hayes's favor.

Where does that leave us? Hayes has licensed its escape sequence and guard time mechanism to two chipmakers, Rockwell and Silicon Systems. If you purchase a modem with one of these chip sets, you are legally allowed to use Hayes's patented technology. However, a competing standard called TIES (Time-independent Escape Sequence) has emerged. TIES is not patented and is free for use by anyone who wishes to adopt it. The TIES sequence differs from the Hayes sequence only slightly. it consists of three plus signs, then the letters AT, and then a carriage return. Some argue that this sequence might be more prone to cause a shift into command mode in the middle of a file. The odds are still very slight that it will happen on any particular transmission. A Hayes white paper on the subject estimates that an individual computer user who transmits files for about an hour a day will encounter about six files per year that cannot be transmitted in full. Companies that send thousands of files a month might discover large numbers of files that can't be sent using TIES, and for reasons that would be a complete mystery to most computer users.

The international standard-setting organization CCITT is not likely to set a standard that incorporates the Hayes escape sequence. However, Hayes has established a de facto standard that has become so widespread that any competing standard will have difficulty prevailing over it.

The Future's Here to Stay

Despite the many problems that currently plague,high-speed modeming, one thing is clear: There's no going back to the days of 2400-bps communications. Modems are going in only one direction, and that's toward faster speeds. So, while fine-tuning your modem may not be anybody's idea of a fun time, it may be worth your while to invest a couple of hours learning a little about modem technology to save a lot of time and money later on.

The good news is that some day soon the nation's homes and businesses will be rewired with digital phone lines, making modems-and modem problems-obsolete. Unfortunately, it may be a long time before PC communications will be as easy as plugging a phone line into the back of your computer and dialing up your favorite online service. You'll still need to buy a terminal adapter and navigate your way through another host of technological issues.

"Hopefully, in another year or two, there will be a standard switch interface for the terminal adapter to talk to," says John Copeland, vice president of technology for Hayes. As for the adapter manufacturers themselves, "People are always going to want to differentiate their products and include some feature or enhancement that the rest of the crowd doesn't have."

That's just modem nature.