HERE'S a computer quiz: What's as long as your thumb, shaped like a trapezoid, comes with 25 tiny holes, and sits at the back of most IBM-compatible computers?
It's a parallel port - the little prong that connects printers to a PC. (Macintoshes use a different, more flexible system.) For years, it worked just fine. Then, the portable computer came into its own, making increasing demands on the venerable connection device. Today, the parallel port is a bottleneck.
Consider two portable machines now sitting on my desk.
The first is a $350 business-card scanner from Pacific Crest Technologies called the CardGrabber. I like the idea. The machine can turn all the business cards I collect into a computer database. CardGrabber scans each card, turns it into editable text, then puts the person's name into the name field, the address into the address field, and so on.
Usually, it's accurate. If occasionally ``Research Triangle Park'' comes out ``Research Mangle Park'' - well, that's par for the course in image-to-text technology. Since the system works off the parallel port, it's easily portable.
But it's also slow, thanks to the parallel port. I watched an entire Olympic ski-jumping competition in the time it took to scan and edit 17 cards. I could type the information faster myself.
The performance penalty is even more noticeable with the second machine on my desk: Micro Solutions' double-speed CD-ROM. Like the CardGrabber, it's portable and hooks right into the parallel port. That makes it far easier to install than an internal CD-ROM drive.
No worrying about ``interrupts'' and ``addresses.'' No fussing with screws or boards. Just a couple changes to the start-up software, and you're ready to go. No wonder the drives are selling well.
The trade-off is its speed. The video and sound performance of the double-speed player is worse than on my single-speed, internal CD-ROM drive. Micro Solutions doesn't pretend the drive will handle the video- and sound-rich CD-ROM standard known as MPC. The real fault, of course, doesn't lie with the machine. It's my parallel port.
My PC and most others in use today have ``unidirectional'' parallel ports. They can send eight bits of data at a time and receive four bits back. That worked fine in the days when the port just transferred information to a printer. Unfortunately, CD-ROM drives send data - lots of it - back the other way. Unidirectional technology just doesn't cut it.
Dan Sweeney, technical support manager at Micro Solutions, figures my parallel port effectively reduces the CD-ROM player's throughput from 300 kilobits-per-second (kbps) to about 100 kbps. Newer ``bidirectional'' parallel ports, which send and receive eight bits, do better - maybe 250 to 300 kbps. But the real turning point is coming soon - a new standard called Enhanced Parallel Port or EPP.
EPP will have throughput up to 50 times greater than my unidirectional parallel port. Larry Stein, who chairs the technical committee responsible for EPP, says the new technology will sweep the PC world within a year. Some computers already have EPP. But it's not clear that they will be fully compatible since the final standard is not yet released.
The new port will also allow printer cables to be five times longer than today's standard 6-foot length. It will be ``plug and play,'' which means the port will be able to tell what peripheral device it's hooked up to. Most important, it will allow users to plug up to eight devices into a single port, greatly expanding the parallel port's usefulness.
Of course, Macintosh users have had this latter capability for years. This is one more example of how the PC is catching up to the Mac - one bottleneck at a time.
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