Classic Computer Magazine Archive COMPUTE! ISSUE 145 / OCTOBER 1992 / PAGE 110

Image Communications Twincom 96/42i. (modem) (Evaluation)
by Richard C. Leinecker

In a crowded field of modems, it's hard to be distinctive. But that's just what this internal 9600 bps modem does--stand out in the crowd. Besides having fast transfer speeds, it implements the newest error-correcting and data-compression techniques. And a unique system of speed buffering allows data to be exchanged between the modem and computer at speeds of up to 38,400 bps.

Installing the card was easy. Step-by-step instructions made installation almost foolproof. I was a bit surprised that the default COM port setting was COM4, since most modems use COM2. Don't worry, though: Setting the port is as easy as flipping several switches as indicated by a chart in the manual. Another surprise was finding there wasn't any telecommunication software included, although that helps keep the price down.

Two different error-correction methods are available. You don't have to worry about either one. When modems connect, they determine and establish the best technique for the circumstances. For those interested in the technical details or for the rest of you, who want to know what to ask the salesman in the store, LAP-M and MNP-4 are the two types of error-correcting methods included. Both of these dramatically reduce the possibility that line noise or other interference will corrupt the flow of information. Another new technology that's built in is data compression. You don't have to know anything about it; the modems figure out what to do when they first connect. The V. 42bis flavor of compression can quadruple data throughput when transferring compressible data. The MNP-5 variety can double the data throughput. All of this means that you'll send and receive information at a much faster rate.

The faster rate of data transfer poses a new problem. Since the modem is sending at a rate of 9600 bps over the phone line while compressing the data, it needs data from the computer at a faster rate than 9600 bps. Why? Remember that compression can usually at least double the data throughput. If the modem is using compression and communicating at a rate of 9600 bps, then, with the doubled throughput, it's sending at an effective rate of 19,200 bps. That means it needs information from the computer at the rate of 19,200 bps. In the best situations, with V. 42bis compression, it's sending at an effective rate of 38,400 bps and needs information from the computer at that rate.

The folks at Image Communications engineered the perfect solution in what they call speed buffering. Regardless of the over-the-phone communication rate; the baud rate of the computer can be set to 38,400 bps. Two internal buffers on the modem card manage the overflows and underflows of data. That way, under the best of circumstances, you can get an effective communication of 38,4D0 bps. At that rate I can send my entire Windows subdirectory (about 12MB)in about 42 minutes. That's incredible!

New technology is great. But it's even better when a well-designed product like the Twincom 96/42i comes on the scene. Its makers have taken the best new technologies available and combined them very smartly, so that in a crowd of competitors, the Twincom 96/42i clearly comes out ahead.


If you use your computer to perform business or scientific calculations, DigiCorp's Q.E.D. may be just the program for you. This package turns your computer into a powerful programmable calculator. chock-furl of scientific, statistical, and financial functions. Q.E.D.'s wealth of features and ease of use put to rest the question, Why not use a pocket calculator?

Q.E.D. performs all calculations in double precision, making answers accurate to 16 digits. Some pocket calculators can match this precision in their internal calculations, but. almost invariably, they must round the answer to 8 or 1D digits to fit their abbreviated displays.

The program provides easy manipulation of complex and polar numbers, something very few pocket calculators can claim. For engineers or others performing advanced mathematical calculations, this feature alone may be worth the cost of the program. Engineers may also like to know that Q.E.D. can use either i or j to denote a complex number's imaginary part.

External modules written in BASIC are supported by Q.E.D. This allows you to use the program's power in custom-written applications. With the ability to compute mean and standard deviations. solve quadratic equations, and perform trigonometric and hyperbolic functions, Q.E.D. has the power to tackle the most complex applications, including business functions; Q.E.D. will calculate depreciation, rate of return, net present value, and future value. It can also create custom amortization schedules with increasing or decreasing payments, and it can optimize savings or IRA plans. An online help system supplements the terse but adequate manual. You'll rarely need to refer to either, though. You can access most functions with only one or two keystrokes, and Q.E.D.'s menu-driven interface makes using even its advanced features simple.

This calculator easily achieves its goal of providing users considerable computational power in an easy-to-use package and at a reasonable price.