Supra 2400 modem. (Hardware Review) (Evaluation)
by Ranjan Bose
Supra 2400 is an external RS-232 modem that I can recommend. It's been around for several years, long enough for individuals, businesses, and BBSs to shake out any hardware bugs that it might have had.
It's smaller than a Beta videotape, is solidly built, and has eight LEDs that indicate the various modem operations. Supra 2400 is a Hayes-compatible smart modem that supports AT commands, extended & commands, and result codes. It has several internal registers for controlling modem functions. The modem works well with most popular shareware and commercial telecommunications programs, BeilTerm, Bobs Term, NovaTerm, and Elite Term being some of the readily available ones.
Supra 2400 is cool running, which certainly adds to its ability to transmit data for long stretches of time without errors. At 2400 bps, transmission is obviously more likely to be affected by phone-line noise than it would at lower baud rates. Supra 2400 uses adaptive equalization and impedance matching like most other modems do and gives you long sessions of error-free transmissions.
Supra 2400 supports several modem tests. A power-on test automatically checks out the modem every time it's turned on. There are also manual and self-running analog and digital loopback tests in which the modem generates and sends signals to itself to check that everything is functioning. One interesting feature of the Supra 2400 is it nonvolatile memory. Even after the power is turned off, the modem will store one telephone number. While this feature is welcome, it's overshadowed by the fact that many other terminal programs support their own phone directories and store dozens of numbers.
There's an error in the Supra manual regarding the store feature. The correct command sequence for storing a telephone number is AT&Z= followed by the dial type (T for tone or P for pulse) and the telephone number, as in AT&Z = T5551234. The equal sign character is missing from the documentation in the manual. This supposedly has been corrected by an addendum, but the addendum wasn't included with my modem. However, using the AT&W command for storing any modem settings is a more useful application of the nonvolatile memory. The settings with AT&W load automatically whenever the modem is turned on, which saves you the trouble of having to reach for the manual or the supplied reference card at each session.
I particularly like Supra 2400's power switch. It used to be that whenever I turned on my computer, my old modem would scream like a cat in heat; now peace reigns with my Supra 2400. If I want to hear a call in progress without insulting my ears, I can control the volume of the modem's speaker via the software. Supra 2400 also has its own independent power supply. Now it takes me longer to warm my coffee on my 64's power supply, but I hardly call that an inconvenience!
The Supra company sells an RS-232 interface for the 64 called Peak Modem Interface ($39.95); any similar interface will work with any RS-232 modem. The least expensive commercial model is the Com-Modem adapter ($19.95) from Aprotek. You could even build an interface with the help of the designs and descriptions available on most online services. If you want to connect your Supra through the Com-Modem adapter, make sure that you order an RS-232 straight-through DTE cable with male DB25P (25 pins) connectors at both ends.
The documentation for the Supra modem is comprehensive, although somewhat technical in places for some users. However, a good telecommunications program takes care of the technical aspects of using a modem, and you never need to bother with all those AT and & commands and what registers do. Troubleshooting is very well covered. And the best news is that Supra 2400 has a street price of less than $100 (cheaper by mail order) and comes with a five-year limited warranty.