The Executive Computer

Modem Makers Are Picking Up the Pace

By Peter H. Lewis
The New York Times

July 15, 1990

Computers are getting faster, more powerful and more reliable, and so too are modems, the devices that allow two or more computers to share information over regular telephone lines. Fairly bristling with advanced circuitry, the new modems achieve their performance by taking over a lot of processing done by computer-based software communications protocols. ''The modem is doing much more processing than the computer,'' said Dennis C. Hayes, president of Hayes Microcomputer Products Inc. of Norcross, Ga., which for many years has set the industry's standards.

The change is important for the new computer systems that can perform several tasks at once, with a communications program running in the background while the main processor is working on other applications. For the last few years, the standard office modem has been able to transfer 1,200 or 2,400 bits of information a second, through modulation and demodulation (hence the name modem). Because of improvements that safeguard the accuracy of data, industry analysts are expecting the standard to make a leap to 9,600 bits a second.

Using such techniques as data compression, which in effect squeezes out the ''white space'' between chunks of information, some makers of 9,600 b.p.s. modems boast that their devices have an actual ''throughput'' faster than 9,600 b.p.s. - several times faster, in some cases. A few brag of speeds that once were thought possible only on a digital phone network, like the Integrated Services Digital Network that is still several years from widespread use.

''Businesses are finally beginning to appreciate higher speed'' in data transmissions, said Greg Szumowski, a data communications analyst for the International Data Corporation, a market research company in Framingham, Mass. He added, ''They are aware that 9,600 is the next step up, and they've leapfrogged over 4,800.'' A 9,600 b.p.s. modem theoretically sends a file in one-fourth the time of a 2,400-b.p.s. modem, and the increased speed makes it economically feasible to exchange larger amounts of data. Because businesses increasingly need access to information stored in computers far away, long-distance telephone charges are a significant expense.

''We find that a lot of companies are changing the way they do business through these technologies,'' Mr. Hayes said. ''For example, a textile company in South Carolina is spearheading an industrial integration system where customers place orders electronically to improve service. Pharmacies and drugstore chains are using dial-in services to do drug-interaction checks, to make sure a prescription from one doctor does not cause ill effects when used with a prescription from another doctor. Companies are realizing that in providing those kinds of services there is a transmission cost involved in sending data. High-speed modems can significantly reduce phone bills and make them more competitive.''

But telephone lines were designed to handle human voices, not computer data. The quality of the line is not critical for voice transmission, because the human brain has superb built-in error correction and data compression capabilities. Computers, on the other hand, are essentially dumb boxes that have to have everything crystal clear. The slightest pop, hiss, whistle, click or echo on a phone line can knock a computer senseless. A single bit that strays out of place can lead to all sorts of problems. Often, if the modem senses that the line quality is inadequate, it will simply drop the connection and force the caller to redial.

When modems try to pump more and more bits down the same standard telephone line, the importance of error checking and correction technology increases. As a result, the Consultative Committee on International Telephone and Telegraph, or C.C.I.T.T., an organization that sets worldwide standards for such things as modem and facsimile transmissions, developed a standard for 9,600 b.p.s.modulation, which is called V.32. If the V.32 modem makes a connection with another modem, it performs a ''handshake'' in which the two devices exchange information about themselves. If the V.32 modem detects that its partner is not V.32, it typically ''falls back'' to a lower standard. ''V.32 is a funny animal,'' said Casey Cowell, chairman and president of U.S. Robotics Inc. of Skokie, Ill., a leading maker of data communications equipment. ''It was originally conceived as a way to transmit data on leased lines over short distances, and it was not really optimized for long-distance connections. The technical trick was to get it to work well with regular telephone lines.''

U.S. Robotics, Hayes and other modem makers quickly adopted the V.32 standard for high-speed communications. Then, in the quest for further speed enhancements, the C.C.I.T.T. developed a standard called V.42, for error checking and correction, and a second standard, known as V.42bis, for data compression.

V.42 incorporates and surpasses earlier error correction standards called M.N.P., for Microcom Network Protocol. Many businesses already have modems that include MNP levels 2, 3 and 4, and they will be able to communicate with V.42 modems. V.42bis also supplants an earlier standard, called MNP level 5. In general, said Mr. Cowell of U.S. Robotics, V.42bis offers about a 35 percent increase in performance over MNP-5 modems on typical data files.

In short, businesses that need to exchange a large amount of data would do well to shop for V.32 modems with V.42 and V.42bis capability. Such modems typically cost $1,000 to $1,600. Because they cut phone bills so efficiently, they have the potential to pay for themselves in a relatively short time.

Modem makers often add proprietary schemes to the industry standards in their efforts to make modems go faster. U.S. Robotics's Courier modems, for example, employ a technology called HST that boosts the effective speed of the V.32 modem to 14,400 bits a second when it is connected to another HST modem. Otherwise, it falls back to the other modem's top speed. Mr. Cowell said HST also greatly improves the chances of a successful handshake on the first try and reduces the time it takes for modems to perform that handshake, to an average of 6 seconds from the typical V.32's 14 seconds.

''That means the HST modem can send 100,000 bits of information before a regular V.32 can send bit one,'' Mr. Cowell said. ''In many applications where people are calling to remote sites to extract data several times a day, every day, those differences add up.''

And last month, Hayes introduced a modem called the Hayes V-series Ultra Smartmodem 9600, for $1,199. The Ultra 96, as it is called, can reportedly achieve pure data throughput of as many as 38,400 bits a second when connected with another Ultra 96.


Copyright 1990 The New York Times Company