One of the many joys of owning a computer is the ability to attach lots of different items to it. Of course, no joy in the PC world is earned without duly fought frustration of having to work through choosing and then configuring these peripherals. My goal within the confines of this column is to give you a basic guide to existing methods of attaching all the cool stuff that is being developed. Also, I'll throw in some purchase suggestions and tips for use along the way.
Right now there are six primary ways to attach devices to your computer, based on the type of port you are using to attach the device to a printer. The ports available are serial, parallel, Small Computer System Interface (SCSI, pronounced "scuzzy"), Infra-Red (IR), Universal Serial Bus (USB), and IEEE 1394 (Firewire).
Have I lost you in all of this nerdese yet? Nope? OK, let's dig in.
A serial port is the computer's oldest port, which was developed for communicating to attached devices, and therefore, is the most limiting. In the standard PC, these ports are represented by COM and a number to designate the port ID. Thus, COM1 is serial port 1. From a PC point of view, serial ports have their neck in the PC guillotine because of newer technologies being pushed along. Serial ports can only transmit up to 112,500 bits per second (bps).
To give you all a frame of reference for speed, we will use 1 megabyte (MB), or 8,192,000 bits, as a benchmark. As a comparison, a serial port pushes data at 1.4 percent of the benchmark. In plumbing terms, if 1MB is a water main coming into a home, the serial port is the copper tube going to the refrigerator's ice machine. The next question is, "What should you use a serial port for?" Modems and devices that do not require a lot of data throughput (a.k.a. bandwidth) should be used on serial ports. Modems are perfect because the telephone companies currently limit them to 56,000 bps. As an example of attached devices, on my system I have two modems using two serial ports, plus my backup power supply uses a third and the docking station for my handheld PC uses a fourth.
The other port you will see on all computers is the printer port, which was developed just after the serial port. Unlike serial ports, which allow one item per port, you can daisy chain items off a printer port. Daisy chaining is like wiring items up in serial connections. For example, from the printer port on my computer I had a tape drive, which in turn was attached to my ink jet printer. So, in order to print, the data would have to flow from the computer through the tape drive, which would see if it was meant for it, and then to my printer, which would print.
Some classic items daisy chained off the printer ports are scanners, zip drives and tape drives. Frankly, printer ports should be used only for printers. Let's go back to my tape drive example. The tape drive would not perform a backup if the printer was on. Both were from the same manufacturer but different divisions. Because the tape drive required a certain communication parameter and the printer another, they were incompatible. I have seen this scene re-enacted time and time again with zip drives, scanners and other peripherals. Life is simply easier by just keeping one item to one port with printer ports.
Nitty GrittyNow, let's muddy the waters even more. It's time to talk about SCSI ports. SCSI is the answer to the limitations of serial and parallel ports when it comes to the number of attached items, throughput speeds and configuration issues. The typical SCSI port can have up to seven items attached to it, with throughput speeds up to 40MBps. A SCSI item is identified by a switch on the device that is set to one through seven. Until recently, SCSI was the unchallenged king of the roost when it came to device management on a PC.
So, where do you see SCSI devices? Macs and higher-end PCs. The Macintosh made the SCSI interface standard many years ago while the PC platform uses SCSI interfaces for heavy input/output intensive devices and applications. For example, let's go back to the tape drive I had attached to my printer port. Well, I sold it to a client without the printer problems I was having, and I bought a SCSI tape drive (SCSI ID 3), added a scanner (SCSI ID 5) and then threw in my SCSI zip drive from my Mac (SCSI ID 4). Most times, though, I use a high-end SCSI card on the servers I deploy. These SCSI cards cost a bundle, allow up to 15 devices and have a max throughput rate of 160MBps. For this type of use, there are no competitors.
Now, let's apply the brakes and talk about Infra-Red (IR) ports. Speed-wise, an IR port is about as fast as a serial port, but the capabilities will be become more prevalent in the near future. An IR port allows a detached device to send data to another device and even swap data. Great examples of this are the PDAs and Pocket PCs. Both the Palm Pilots and Pocket PCs have an IR port, which allows you to send data to another device. The classic example is two Palm Pilot users swapping their business cards by "beaming" the data between their IR ports. Cute and nerdy, huh?
Here is how this technology will apply to your industry in the near future. I can take my HP Jornada Handheld PC, create a document in my Pocket Word program and beam it to a laser printer. Companies now are developing the programs that allow you to print an invoice in the field for a client and then synchronize the data with your master accounting program, either by serial port, phone or IR port.
OK, soapbox time. Here is my up-and-coming favorite port, the Universal Serial Bus (USB) (www.usb.org). USB was developed about five years ago as the replacement to the serial port. It sat on the shelf until Apple replaced all of its serial ports with USB ports. While the columnists berated Apple for doing so, Apple set about a chain of events that has made life better and easier for all of us, to which serial ports will no longer be installed on new PCs within three years! Oh, those columnists are eating crow now.
Why is USB so great? Two key reasons: speed and flexibility. A USB port allows up to 1.2MBps of data to flow through it. USB 2.0, which has been released by the time you read this, allows up to 60MBps of data. The other benefit is flexibility. Name a device É it can be attached to a USB port. Yes, even the old serial and parallel port devices can work on a USB port.
If you need more then one device, a USB port theoretically can handle 127 devices. Because of bandwidth issues (60MB of bandwidth divided by 127 devices equals slow throughput), that would not be practical in all situations. However, you can add more USB ports to your PC to compensate.
Now, the best part of USB's flexibility É it is hot swappable. Let me explain. A hot-swappable device can be plugged in, removed, and turned off while the PC is in use, without impacting the PC. For example, if my printer is not plugged in when I turn my PC on, it may not print. Likewise, I cannot just add in my SCSI zip drive without rebooting my PC. However, if I had a USB zip drive, I could plug it into my PC whenever I wanted, and my PC would reconfigure itself on the fly.
Qualifying FactorsI do need to address some limitations to USB. Because PC manufacturers were using USB as a marketing tool, not all USB ports on older PCs are USB compatible. USB also is limited by the operating system being used. USB is 100 percent supportable on iMacs and the newer Macs. Some flavors of Windows 95 support USB, while Windows 98 and 98se support USB. Windows NT Workstations 4.0 does not support USB.
Some intrepid companies have made drivers for their USB devices for this operating system. However, the drivers will work only with that device. Thankfully, Microsoft saw this flaw and Windows 2000 Professional and Server are both USB compatible. So, if you have a Mac with a USB port, Windows 98, or are brave enough to try Windows 2000, take the dive into USB devices. My clients love them.
Last but not least, IEEE 1394, affectionately known as Firewire (www.apple.com/firewire/). Firewire is another development spearheaded by Apple. Like USB, it is hot swappable, allows up to 63 devices and is just as easy to use as USB. Throughput-wise, it is ahead of USB. Like USB, companies are preparing FireWire products to include digital cameras, both still and video, scanners, hard drives, removable drives - including CDR and CDRW drives - and printers.
I believe USB will win out in the consumer market, but the high-end graphics industry probably will use the Firewire technology even more because of its ability to handle video. Either way, USB and Firewire ports are available on all PCs, whether built in to the PC or added later via internal cards.
However you choose to connect devices, the number of devices and their capabilities and potential uses within your business are growing exponentially. In my next column, I'll look into part one of a two-part series on computer security. Until then, download your monthly anti-virus update.