Q Does USB really let you connect 127 devices to a single port and provide power for each device? I don't see how I can daisy chain my USB devices as easily as magazine articles claim.

A Yes, theoretically you can attach 127 devices to your system; and yes, a Universal Serial Bus connection does provide limited power to each device. But there are some important practical issues you need to consider to successfully hook up USB peripherals to your system.

To establish a USB connection, you need both hardware and a BIOS that support USB as well as the appropriate version of Windows. Just because your motherboard has a USB port doesn't mean you have the proper BIOS and hardware. To see if your PC is USB ready, you can run USBReady, a free utility available on this monthÆs CD or from www.usb.org/faq.html. It examines your system's hardware, installed drivers and Windows version and identifies what, if anything, is needed for USB to work.

Caption: USBReady tells you if your PC is able to use USB devices

If you're having trouble with your USB port and your motherboard is more than 18 months old, the port may be improperly designed. Some motherboard manufacturers jumped the gun and included USB ports before the final USB specifications were completed. To see whether your motherboard suffers from this problem, call your system vendor.

And if your motherboard does have an older, non-functional port, or it doesn't have a USB port installed, you can add ports via a PCI expansion card such as the $79 PCI-USB Converter card from Dynalink (www.dynalink.com.au).

Both Windows 98 and the last versions of Win 95 (OSR2.1 and 2.5) support USB. But if you use Win 95, always check with the peripheral manufacturer to ensure Win 95 USB drivers are available for it.

If your system has everything it needs for USB and you still can't get a USB peripheral to work, make sure USB is activated in your CMOS setup program. To enter CMOS setup, hit the appropriate key (as indicated by a screen prompt) when your computer first starts up. Where in the setup program you find the USB setting ù and what it is called ù varies depending on the BIOS version and brand.

To hook up more than one device to a single USB port, you need a hub. The two rectangular external connectors built into new motherboards ù which make up the root hub ù allows you to attach one peripheral to each port. And if those devices have their own built-in hubs with external connectors, you can piggyback additional peripherals on the root hub.

For example, the Philips Brilliance 151AX Flat Panel monitor comes with a four-port hub in its base that offers a convenient way to plug in a mouse, a keyboard and other desktop peripherals. And if one of those newly attached peripherals has its own built-in hub, you can continue adding more devices to the chain. But not all peripherals possess an on-board hub. In such a case, you can buy a dedicated four-port hub like the $199 USB hub from Dynalink.

USB ports don't deliver just data to peripherals; they also deliver power. USB hubs come in two types: bus-powered hubs, which draw power from the incoming connector and can output up to 100mA per port; and self-powered hubs, which draw power from their own power cord and provide up to 500mA per port.

If your attached USB peripherals draw more current than the bus can support, the entire bus may shut down. You can check whether this potential conflict is a problem for you by looking for a warning icon next to the Universal Serial Bus Controller entry in Windows' Device Manager.