Sarasota PC Monitor
Practicing the Black Art (09/01)
Understanding Ports
by Vinny La Bash, vlabash@home.com
Member of the Sarasota Personal Computer Users Group, Inc.When it's time to shop for a scanner, printer, PDA, cordless phone or other peripheral that needs to be connected to your system with some kind of cable, one of the biggest decisions you have to make is how to hook it up to your computer. How should you hook up that scanner? Should you buy one that attaches via a SCSI port, parallel port or USB port? Maybe you should go for an infra-red connection. Most peripherals only let you connect to one kind of port, and not all computers come with every option. Here's a look at the major ports and connectors you'll find on your computers and how they work.
Serial
Serial ports are usually used to connect analog modems so you can connect to the Web. Many digital cameras also use the serial port to transfer image files to the computer. These ports carry only one bit of data at a time, causing a real problem with speed. There isn't a slower port on your computer. Serial ports can be hard to configure for the peripherals to work properly, and problems can be very difficult to diagnose and correct. This is old technology and heading the same way as the dodo bird. Avoid it if possible and go with USB.
Parallel
Parallel ports are widely used for connecting printers to the computer. Because they can carry data 8 bits at a time on parallel paths, they are much faster than serial ports. That's why many flash card readers plug into the parallel port. Since computers come with only one parallel port, if you use a flash card reader, be sure it has a passthrough connector so you can plug the reader into the one and only parallel port, and then plug your printer into it. If the reader doesn't have this capability, you have to keep swapping cables. Some manufacturers want your parallel port to connect scanners, Zip drives, and CD-Rewriteable drives. Though it's usually easy to daisy chain two parallel devices, you're asking for trouble adding a third. Our advice is the same as with a serial port. Go with USB if possible.
PS/2
Most systems that use Windows have a small diameter cable that begins on your mouse or keyboard and ends in a round 9-pin connector to the back of your computer. This type of connector will probably disappear in a year or two. If it's working, leave it alone.
Game port
Game controllers on Windows systems are difficult to configure. If you have the option of buying a joystick that uses USB vs. the game port (which is usually on your sound card), go for the USB. Some folks use this port to connect musical instruments such as keyboards, electric guitars, and so forth. Those who need this type of MIDI (Musical Instruction Digital Interface) connection should consider buying a MIDI board, which is far more suitable.
SCSI
Small Computer System Interface (SCSI, pronounced "skuzzy") has never gained widespread popularity because it's hard to install and configure. It's also considerably more expensive than other types of connections. Its biggest advantages are speed and the ability to connect more than one device to the same port. You plug your SCSI hard drive into the port and then plug your scanner into the hard drive, chaining up to seven devices per SCSI port. This process, called "daisy-chaining" reduces the number of slots taken up by all of these devices. SCSI ports are fast but on PCs you need a separate SCSI card and installing it can be a downright pain in the neck. SCSI is also being gradually replaced by USB.
USB
As input and output demands have increased, serial, parallel, and even SCSI ports have become bottlenecks to system performance. To heighten performance, USB (Universal Serial Bus) and even faster IEEE 1394 (Firewire) ports (described next), are being added to systems. Both of these ports have some features in common. They can each:
* Use thin cables to make connections easier.
* Daisy-chain devices so only a single port is needed on the computer.
* Support Plug and Play so the computer will automatically recognize a new device. (This capability is still a bit quirky, so it's sometimes referred to as "plug and pray.")
* Support hot swapping (adding and removing devices without first turning off the computer).
* Distribute power along its own cable so low-consumption devices can operate without a separate power cord.
The universal serial bus is the easiest way to attach printers, scanners, digital cameras, input devices, and most other peripherals. The exceptions are unusually high-speed devices, such as high performance hard disks and digital camcorders. The practical limit is three USB devices per port. The theoretical maximum is 127 connected to each other in a daisy chain. USB works at 12 Mbps and the even newer USB2 offers much higher transfer speeds. Windows users take note: USB only works properly with Windows 98 or higher.
FireWire
Also called IEEE 1394 or i.Link, FireWire is designed to connect high-speed devices such as hard disks and camcorders. FireWire peripherals are as easy to configure as USB. Until FireWire ports become standard, you'll need to open your computer to add a FireWire card or add it via a PC Card for laptops.
Though external ports provide a relatively easy way to add hardware, some devices such as hard disks, CD-Rewriteable drives, and DVD-ROM drives are best added internally using the interior connector cable that hooks to the motherboard. Internal installation provides the best integration among hardware devices. Other hardware, such as memory and graphics cards, cannot be added externally. :
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Copyright 2001. This article is from the September 2001 issue of the Sarasota PC Monitor, the official monthly publication of the Sarasota Personal Computer Users Group, Inc., P.O. Box 15889, Sarasota, FL 34277-1889. Permission to reprint is granted only to other non-profit computer user groups, provided proper credit is given to the author and our publication. We would appreciate receiving a copy of the publication the reprint appears in, please send to above address, Attn: Editor. For further information about our group, email: admin@spcug.org/ Web: http://www.spcug.org/
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