Connecting peripherals to computers has come a long way.  In the “old days”, keyboards, mice and printers were connected to computers with “parallel” and “serial” cables.  These cables worked well, unless you accidentally disconnected them while the computer was running.  This brought your computer to a screeching halt.  You had to shut down the computer, reconnect the cable, and restart.  In 1998, Apple’s iMac debuted with a new way to connect peripherals – USB (Universal Serial Bus).  USB carried data faster, and was “hot-swappable” – you could plug and unplug the cables with impunity.  The rest of the industry followed suit, and today USB is the standard for connecting keyboards, mice, printers, scanners, external CD burners, digital still cameras, even hard disk drives.

Before we continue, here’s a quick and really simple refresher on computer data.  Data on computers is made up of “bits”, which are ones and zeros, the language that computers understand.  Bits are arranged in groups of eight, which are known as “bytes”. This article, as a MS Word data file on my computer, is 224 thousand bits in size – divided by the eight bits in a byte, we see it on the computer as 28 kilobytes, or KB.  A one megabyte (MB) digital photo consists of (you guessed it) one million bytes (or eight million bits).  A 20 gigabyte (GB) hard drive can store 20 billion bytes of data.

One measure of data transfer speed is bits per second (bps).  Let’s look at a 1 MB digital photo file (remember, that’s 8 million bits) and see how long it takes to move across some common data transfer protocols, from slow to fast.  A 56K (the K is for kilobits) modem can transport 56000 bits of data per second, or roughly 7000 bytes (7 KB) per second. Therefore, a 56K modem would take 142 seconds (over two minutes) to transfer the file.  A 256 Kbps cable modem connection would transfer it in around 30 seconds.  A USB 1.0 cable, which can transfer at 12 million bits per second (Mbps), would transfer the 1 MB file in less than a second.

Once we get into the even faster protocols, it’s easier to think of the transfer rates in terms of megabytes per second.  Standard ethernet networks can move 12 MB per second.  FireWire and USB 2.0 both move 50 to 60 MB per second.  Apple’s new FireWire 800 weighs in at 100 MB per second.  Finally, the new Gigabit Ethernet connections blaze along at 125 MB per second.  Remember that 20 GB hard drive we mentioned earlier?  Gigabit Ethernet can transfer that whole drive in under two and a half minutes.  That’s pretty fast.

But, hey, who needs wires and cables at all?  Wireless networking is now the rage, with “hotspots” popping up in coffee shops, bookstores, hotels, and airports.  The 802.11b (Centrino) wireless standard can move 11 Mbps (or around 1.5 MB per second), and the emerging 802.11g standard easily doubles that rate.

Another wireless technology gaining ground is known as “Bluetooth”.  Bluetooth uses a globally available frequency band (2.4 GHz) to enable short-range (about 30 feet) wireless connections between desktop and notebook computers, personal digital assistants (PDAs), mobile phones, camera phones, printers, digital cameras, keyboards, and mice.  Bluetooth’s speed is roughly equivalent to that of a USB cable.

You’ve probably seen (or even used) a wireless mouse or keyboard.  In the past, these wireless peripherals were linked to the computer via infrared, which could only operate in line-of-sight with the receiver, at close range.  Since Bluetooth is a radio receiver, it doesn’t have these limitations.

© 2003 Peter F. Zimowski