Classic Computer Magazine Archive ANTIC VOL. 3, NO. 3 / JULY 1984


An advance look at the fourth generation modem


The modem may be the Rodney Dangerfield of the computer gear -- it gets no respect. Maybe it's the funny earmuffs (on accustical models) or the jargony, newspeak name, but people seem to disdain the Modem, or at least to take it for granted.

They shouldn't, though. The modem is as significant, and will soon be as ubiquitous, as the telephone. The reason? The modem is the device that links you via phone lines to the rapidly expanding universe of computer-based information.

And a new kind of modem is now stepping into the spotlight. Called a "virtual" modem, it can mimic any of the capabilites of its more straightjacketed predecessors, and it's smart, too - smart enough to rebuff even the most ingenious hacker. It's a true "fourth generation" modem.

The first generation modem was a simple, acoustic unit that converted digital electronic signals into audible, analog tones and vice versa. The two ends of a telephone's receiver fit into two indentations on the acoustic modem that look like earmuffs. Next came the direct-connect modem that plugs into your computer -- no earmuffs on this device! Then the third generation modem was introduced, along with onboard programmable features such as autodial, autoanswer, number storage and variable speed.

The problem with all of these modems is that their manufacturers were unable to agree upon a standard for the industry. An international standard has been established by the Brussels, Belgium-based CITTT (an international organization made up of official representatives from governments around the world who have experience in the fields of telecommunications and banking, but influential U.S. companies such as IBM and AT&T have ignored this standard in bids to force the industry to move in their directions. There have been no clear winners in this struggle, but as a result of it there currently are a lot of different kinds of modems on the market.

Enter our hero, the fourth Generation, or virtual modem. This device automatically configures itself to match the modem it is communicating with, no matter what speed, feature or protocol is being used.

A protocol is the means by which one modem talks to another. In human terms, a conversation in French requires that the French protocol of meaningful sounds be used, and that these sounds be arranged in a specific syntax. If I talk to you in French and you understand only English, we need a French/English interpreter. The modem performs a similar function for computers, but to do so fully it requires memory and processing capabilities of its own.

The virtual modem has these capabilities. Controlled by a microprocessor, it "knows" when your data number is called, and answers automatically. It "asks" who is calling, both in terms of the equipment being used at the other end and of the person or organization making the call. It automatically configures itself to match the requirements of the other equipment, and requires that the other party pass a security test of great sophistication before it allows access to your computer. It captures messages in its own buffer, and either prints them directly or saves them onto media.

MicroTelecom of San Rafael, California, is one of the first manufacturers planning to introduce a virtual modem. Their prototype model is able to shift among speeds from 300 to 2400 baud, recognize all extant modem types and protocols (including 103, 212, x.21, x.25, SNA and IBM-3274), and operate in either full or half duplex, and synchronous or asynchronous modes, while providing both autodial and autoanswer capabilities.

Other brands and future models will undoubtedly expand upon the features of this early version of the fourth generation modem, but one thing is certain -- these new modems will rapidly, earn our respect.

One of the designers of MicroTelecom's virtual modem prototype, Bill Lee currently works as a designer for Marsten Systems Corp. of Los Altos, California. Marsten is scheduled to distribute MicroTelecom's fourth generation modem to the consumer market when the device is introduced .