MODEM OPERANDI

By J.B. MilesSpecial to GCNOnly a couple of years ago, the term mobile computing might have conjured images of business-suited pack mules'resolute road warriors marching through airports with 10 pounds or more of extra gear in their luggage.Today, the image, like the equipment, is sleeker and faster. PC Card modems and the fast, powerful notebook computers they plug into'built for speed as well as comfort'have made life on the road relatively easy, even fun if you know what you're doing.The 56-Kbps PC Card modems in this guide represent the pinnacle of current dial-up analog performance. You're not going to get many digital or fast cable connections while traveling, but good old Ma Bell and her cronies still provide nearly ubiquitous telephone lines.In rare cases, you'll get close to 56-Kbps performance from one of them, but most times you'll have to settle for considerably slower throughput. All 56-Kbps PC Cards can, if necessary, drop back to 33.6-Kbps V.34 operating speeds. This is far from the T1 speeds we all crave, but it is perfectly adequate for most travelers, except those who need to transfer huge files.As for comfort and ease of use, all PC Cards fit easily into the Type II or Type III slot of your notebook and most are easily configurable via Microsoft Windows Plug and Play. Most come with Windows 95, 98 and NT drivers, and a few also support Mac OS, OS/2 or some variants of the Unix operating system.Not long ago, plug-and-play PC Card capability was more theoretical than real. But today, even novices can get a PC Card up and running in minutes simply by popping in a floppy with the correct driver and following the manufacturer's setup directions.Prices for 56-Kbps PC Card modems have dropped significantly during the past few months, and they haven't bottomed out yet. Plenty of basic units'for fax and data only'are available for less than $100, and savvy buyers can do even better by shopping online. Many units listed in the accompanying chart that combine 56-Kbps modems and 10-Mbps or 10/100-Mbps Fast Ethernet capability in the same card also have dropped to $300 or less.Before you hit the road, however, a few cautions about 56-Kbps PC Cards are in order.Dispense with the notion that any 56-Kbps modem will provide full 56-Kbps throughput. The Federal Communications Commission has imposed limitations dictating 53 Kbps as the fastest a 56-Kbps modem can download files, and 33.6 Kbps is the fastest it can upload.In truth, even these limits are theoretical. The top speed of any modem is more often determined by line conditions than the modem's design or the protocols it uses.If you are telecommuting from a rural area that has poor line quality'lots of electromagnetic noise or hits'even the fastest, top-of-the-line 56-Kbps PC Card with V.90 protocols will slow down.Ditto for dialing up from a hotel room. Virtually all hotels and motels switch your room's phone line through a digital private branch exchange, and that will destroy any hopes of a high-speed connection. Expect 28.8-Kbps throughput at best, and prepare to settle for around 23 Kbps if you really want to prop your legs up and watch HBO while sending e-mail to the office.As for all the vendor hype about V.90 compliance, take that with a grain of salt, too. The V.90 protocol ratified last year by the International Telecommunications Union put an end to the war between camps of manufacturers who supported either the x2 or the K56Flex standard for 56-Kbps modems.For users, adoption of V.90'theoretically'took the worry out of buying a modem that might be incompatible with an Internet service provider's bank of server modems. But it didn't put V.90 suddenly at the tips of everyone's fingers.There are a couple of points to keep in mind when buying a 56-Kbps V.90 PC Card modem. First, find out whether your Internet provider supports V.90 yet. If it doesn't, then a V.90 modem might bog down and run even slower than an older PC Card with x2 or K56Flex protocols.Second, read the product literature carefully. If your new 56-Kbps PC Card is V.90-capable, you'll have to install a new V.90 driver. This can result in a few pitfalls, even for experienced users (see Close-up at right).That said, it's a good time to buy a 56-Kbps V.90 PC Card modem. The old 33.6-Kbps V.34 PC Card is a bit slow for extensive, mobile Web crawling. Most Internet providers now have 56-Kbps connections, and most of them will support V.90 protocols by year's end.To have all your bases covered, buy a modem that manages all the 56-Kbps protocols'x2, K56Flex and V.90. Because 56-Kbps speeds probably are best for dial-up telephone line connections, your 56-Kbps V.90 PC Card might be the last modem you'll ever have to buy.Here's what to look for:CardBus is the newest 32-bit standard for PC Card interfaces and is well designed for the newest Pentium III notebooks. It provides a 32-bit data path and provides for bandwidths of up to 123 Mbps. CardBus modems also require less voltage than 16-bit units.But keep in mind that, although CardBus definitely enhances Ethernet throughput, it usually doesn't affect modem throughput much. If you have a new notebook, consider a CardBus modem or dual 56-Kbps-Ethernet card. Otherwise, don't worry about it.