¢ o=o=o=o=o=¢¢ Modern Modems¢ by Alan Sharkis¢¢ When I started modeming with my Atari¢ system, it was with an Avatex 1200¢ baud modem. There was nothing fancy¢ about it. It might have taken me a¢ few hours of exploration to find out¢ what kind of configuring was possible¢ on it, but basically, it worked out¢ of the box. A bit later on, I bought¢ a 2400 baud, error correcting and¢ compressing modem. It was a Practical¢ Peripherals v.42bis. Once again,¢ there wasn't much that had to be done¢ to it to make it work. When I bought¢ my first PC, a '286 machine, I simply¢ added some cables and an AB switchbox¢ to the modem so it could serve the PC¢ as well as the Atari. Once again,¢ there really wasn't much to configure¢ for each machine, and a simple¢ initialization string sent out from¢ each computer's terminal program at¢ bootup did the trick.¢¢ My next PC contained an internal US¢ Robotics (now 3Com) 28.8 Kbps modem¢ that was configured by the people who¢ assembled the PC for me. Of course,¢ I went over the way it was done, and¢ read its manual to see if I could¢ duplicate their efforts, if¢ necessary. It became necessary when¢ I switched from Windows 3.1 to¢ Windows 95. The modem was not¢ considered "plug-and-play," and I had¢ to reconfigure everything again. No¢ sweat! Only a few hours of my time¢ to make the switch of operating¢ systems, with perhaps a half-hour or¢ less of that time taken up with modem¢ concerns. Meantime, my Atari was¢ still happily purring along at 2400¢ baud. No Atari file that I could¢ find was so large that I couldn't¢ reasonably up- or download it in a¢ short time even at that slow speed. ¢ PC files were another matter. But I¢ couldn't help thinking what the¢ process would be like if I switched¢ my Atari over to an external version¢ of the modem I had in the PC.¢¢ I've had many opportunities since¢ then to configure modems for fellow¢ Atari 8-bitters. It has become a¢ most frustrating experience for them,¢ and sometimes for me. One source of¢ that frustration is that modems are¢ sold with the assumption that you¢ will use them with a PC or Mac. That¢ kind of thinking is so entrenched¢ that the modems themselves have no¢ DIP switches, must be configured¢ through software, and manuals are¢ often not worth the paper on which¢ they are printed. The manuals today¢ leave almost everything to the setup¢ programs included on 3.5" floppy or¢ CD-ROM to be run on that PC or Mac¢ the modem manufacturer assumes you¢ will be using. You're lucky if you¢ get a list of commands, and then¢ there are often limited or confusing¢ explanations of those commands. But,¢ having been through the process with¢ some of the members, I felt prepared¢ to do it for Ron Fetzer when he asked¢ me to help him.¢¢ Ron was given a 56Kbps, external, US¢ Robotics modem by a neighbor. Ron¢ assumed, correctly, that he could run¢ the modem at up to 9600 baud using¢ his Atari and either his p: R:¢ Connection or his 850 Interface. He¢ was not prepared for the fact that¢ his neighbor had, somehow, lost the¢ manual and the power supply. So, Ron¢ took my advice, secured a power¢ supply and a manual from the¢ manufacturer and tried the modem at¢ its initial factory settings. He¢ connected the modem using the same¢ special Atari modem cable he had used¢ successfully with his 2400 baud¢ modem. He fired up Ice-T 2.72, set¢ the baud rate to 9600, and dialed a¢ number. The modem dialed and¢ connected, but then would neither¢ transmit nor receive data.¢¢ Ron brought the modem to the OHAUG¢ meeting in August, where we confirmed¢ what it was doing. However, under¢ the pressure of several people trying¢ to fix a 1050 disk drive at one end¢ of the room and the anticipated¢ arrival of our president and the¢ formal start of the meeting, I¢ decided the modem had to come home¢ with me. At home, I also confirmed¢ what the modem was doing.¢¢ The US Robotics manual for Ron's¢ modem is a bit better than most. It¢ lists the commands, with descriptions¢ of each, in alphabetical order. It¢ also has, predictably, a lot of space¢ devoted to setting the modem up under¢ DOS, under Windows 3.1, and under¢ Windows 95. In addition, each of¢ these topics is doubled because the¢ manual covers both the internal and¢ external versions of this modem. I¢ didn't need any of that stuff for¢ this job. I did need the annotated¢ list of commands, and prayed that I¢ wouldn't have to resort to¢ configuring individual s-registers. ¢ I was comforted by the fact that any¢ changes I made could be saved in what¢ is refered to as "profiles" in the¢ modem's non-volatile memory. So, I¢ took that list of commands and¢ divided it into those that had an¢ obvious impact on Ron's situation,¢ those that obviously didn't, and¢ those in a gray area in-between. I¢ decided that I'd try the first group¢ right away, changing each setting,¢ trying the modem, and changing the¢ setting back if it didn't provide the¢ desired result. At the end of going¢ through this group, Ron's problem was¢ still not solved.¢¢ I decided to try the questionable¢ commands next, and here's where I hit¢ pay-dirt. The command, "AT&Rn"¢ turned out to be exactly what I¢ needed. "AT&R0" was listed as¢ RESERVED. I knew that was not¢ appropriate. "AT&R2" was the factory¢ default, and its description was,¢ "Received Data to Computer Only on¢ RTS." But, "AT&R1 -- Modem Ignores¢ RTS," turned out to be correct. ¢ After finding that out, I stored the¢ setting in the modem with an¢ "AT&W0."¢¢ Now, why did that happen? I had¢ previously, as part of my first group¢ of commands, put the modem into¢ software flow control only, and there¢ was no change. Also, the RTS line is¢ included in the Atari modem cable. ¢ (I know -- I checked the P: R:¢ Connection manual for the pinout.) A¢ call to Frank Walters cleared up the¢ mystery. Even though that line is in¢ the cable, and PCs usually use it,¢ the Atari ignores the state of the¢ RTS line and, therefore, SO MUST THE¢ MODEM. Ron now has a modem that will¢ function at 9600 baud -- faster if he¢ goes to a Black Box or MIO -- and¢ I've learned something.¢¢ I think a note here about modem¢ cables is appropriate, too. If we 8-¢ bitters are going to use non-direct-¢ connect modems, they must be external¢ modems, and they must be connected to¢ our interface with a cable. This¢ cable may LOOK like a "standard" 9-¢ pin to 25-pin RS-232 cable, but it¢ just isn't. You can't go into a¢ computer store and pick up such a¢ "standard" cable and expect it to¢ work. If you did, the first thing¢ you'd notice is that the 9-pin end¢ has a female plug and so does your¢ interface! You might be tempted to¢ go back and pick up a gender-changer¢ to solve that problem. The clerk in¢ the store would be glad to sell you¢ one. After all, he sold you the¢ cable, and here's one more item he¢ moved. But when you got home, the¢ cable still wouldn't work. You see,¢ the "standard" for that so-called¢ "standard" cable was developed by IBM¢ _AFTER_ Atari had produced the 850¢ Interface! (Maybe we should claim to¢ be standard since we were there¢ first, but that's another matter.) ¢ So, what should you do? One approach¢ is to take a "standard" cable, cut¢ off the 9-pin connector, which is¢ probably factory-molded. Then, with¢ the following pinout, either solder¢ or crimp the leads (which you've¢ buzzed out to identify them) to the¢ pins of a DB9 male plug:¢¢ DB25 Male DB9 Male¢ --------- --------¢¢ 20 1¢ 8 2¢ 2 3¢ 3 4¢ 7 5¢ 6 6¢ 4 7¢ 5 8¢ Frame to No connection¢ shield wire to shield¢¢¢ I've done this a few times, but I¢ don't advise that you do it. You'll¢ need the male plug, either crimp- or¢ solder-type, and a shell. Add the¢ cost of those items, and perhaps¢ tools and solder to the cost of a¢ factory-assembled "standard" cable¢ WHICH YOU MUST CUT, the time it takes¢ to trace out the leads (all 25 plus a¢ shield) and do the crimping or¢ soldering, and you're better off¢ ordering an Atari modem cable from¢ Best, B&C, or American TechniVision¢ (if they still have them.) Any¢ factory-molded cable is going to be¢ more reliable than one that you can¢ assemble, anyway.¢¢ o=o=o=o=o=¢¢¢
