Open your serial box


Tip
The universal serial bus is not Kellogg's idea of public transportation. It's a radical rethink of peripherals connections that will replace serial and parallel ports. One USB port can link your PC to 127 devices at up to 12Mbit/sec.
USB will connect just about every kind of peripheral except those demanding very high speed connections, such as hard drives. It gives every connector its own jack and links all devices with one type of cable, without the usual hardware hassles. You knot together as many USB devices as your PC can handle by connecting them to hubs -- peripherals with extra USB jacks. USB also offers Plug and Play for peripherals, can distribute power to low-power devices, and accommodates smaller PCs (especially notebooks).
This is a grand idea and the future of most external computer peripherals.
But keep in mind that these peripherals have not yet arrived. And when they do appear in force, you can add a USB expansion board to your existing PC.
In the meantime, if you already have a PC and serial devices and too few ports to link them, use the following tried-and-true serial expansion options:
· A port adaptor expansion board can add two or more serial ports if your system can handle them. Check your available resources with Microsoft Diagnostics (the msd.exe program that accompanies DOS) or Windows 95's Device Manager. Windows 95 can handle eight serial ports, but you'll probably want to stick with four. If you want to connect a modem, be sure you get a 16550A or later UART chip on the board or, better still, a high-speed enhanced serial port.
· A switch box lets you divide up the ports you have if you cannot add more. Although inconvenient -- you must physically move the switch to choose between devices, and you've still got the hassle of changing driver software -- a switch box eliminates the nuisance of plugging and unplugging cables. Avoid expensive adaptors, and match the connectors on the switch box to your peripherals. A nine-wire switch works in most situations.

Category: Hardware
Issue: Feb 1997
Pages: 175-176

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