Jack Schofield
Two years after it was launched, the Universal Serial Bus (USB), a connector designed to replace serial and parallel printer ports on personal computers, should start to take off this Christmas.
More than 100-million personal computers have been shipped with built-in USB ports, software support has been provided in Windows 98 and Mac OS 8.5, and more than 450 firms have signed up to offer peripherals such as printers, scanners, modems, digital cameras, joysticks, mice and loudspeakers with USB connections.
Retailers like the idea, because USB ports have been designed to make peripherals much easier to install, and the same USB peripherals will work with both PCs and Macs, using different software drivers. In particular, USB should reduce the number of scanners returned after installation failures owing to what is called “pilot error”.
Users will benefit because USB peripherals are “hot swappable” -they can be plugged in and unplugged without restarting the computer. USB also offers higher speeds than earlier ports, and can connect more devices – up to a total of 127.
But USB may have teething problems, because not all manufacturers will have followed the specification exactly, and not all products being launched have been tested for interoperability, according to David Murray, the product marketing vice- president with USB specialist supplier Entrega Technologies, California.
Murray was an originator of the multi- vendor USB specification when he worked at Compaq Computer, and he holds patents on some of the technology. The USB Implementers Forum held “plug fests” or “compatibility workshops” where suppliers could test their equipment, but Murray says he’s seeing products bearing the USB logo from “vendors that have never even shown up to a single compatibility workshop”.
Some of the problems are connected with one of USB’s benefits: its ability of to carry electrical current. Because electrical resistance will cause a power drop over the length of the wire, USB cables have to be manufactured to precise length-to-gauge standards. The idea of consumers figuring out that a 24 gauge wire can be 2m long doesn’t bear thinking about.
Another potential problem is that the USB specification allows both powered and low- powered USB ports, which provide 500 and 100 milliamps respectively. A peripheral that expects to draw 500 milliamps will not work when plugged into a low-powered port.
Even with powered hubs – little boxes that convert one USB port into four or more USB ports – there can be problems. A four-port hub should have a power supply that can deliver two amps. “But we’ve seen several four-port hubs with one amp power supplies,” Murray says. “You really have to open the box to see the power supply to know that it’s not compliant.
“When a new technology like this gets out to the marketplace and users have problems, there go the benefits of USB right out the window,” he says.