Mac Musings

A Pox on CD Burning

Dan Knight - 2002.08.21 - Tip Jar

Last week, Iomega pushed the Zip drive to the next level, announcing a 750 MB drive and media. Over on her website, Ms Geek asks if Zip is anything more than a quaint relic.

Good question.

Random Access

Once upon a time computers used punch cards, paper tape, and magnetic tape to store information. Data could only be accessed linearly.

Then came hard drives, which allowed random, nonlinear access to data. Instead of having to zip though yards and yards of tape, the drive head could go right to the platter, track, and sector where your data was. It revolutionized computing, giving us hard drives, floppy discs, magneto-optical (MO) drives, and Zips.

With any of these media, data can be read or written just like that.

Linear and Random Access

When Sony and Philips invented the CD, they used the same paradigm as the older vinyl record - a single continuous track of data going from the edge of the disc to the center (or vice versa). They encoded information about where each track began, making it easy to skip songs, just as the older LPs had visual indicators where one track ended and the next began.

The medium itself is linear, but it can be accessed randomly. The next logical step was the CD-ROM, which used the same technology as the CD, but stored computer data instead of songs. It was slow, but it could store over 600 MB of data. It eventually replaced the floppy disk as the best way to distribute software and AOL packages.

CD-R, the Curious Hybrid

Today it's really not hard to burn a CD using CD-R or CD-RW media. Pick your tunes in iTunes, pop in a blank, and burn away. Likewise, the Mac OS makes it easy to burn your data to CD: pop in a blank, prep it, drag over your files, then burn.

Unfortunately, it's not as fast as it sounds. In fact, it's a frustratingly slow process because of the way Apple insists on doing things. The Mac OS and iTunes won't simply read files and then write them. Here's what happens when you burn a data disc:

  1. Insert blank CD-R or CD-RW.
  2. Prep disc by giving it a name, choosing data format.
  3. Select files you want to copy and drag them to new CD image.
  4. Mac OS reads your files and copies them to your hard drive, even if they're already there.
  5. To actually burn the disc, drag its icon to the Trash. The Mac OS will now write your files and then verify them.

And it's only a little different in iTunes

  1. Select your music files in iTunes.
  2. Insert a blank CD-R and tell iTunes to burn.
  3. iTunes "unrips" your compact MP3 files to full sized music files. This can take a while.
  4. When this is done, iTunes can finally burn your music CD.

And you'd better have 650-700 MB of free hard drive space to deal with all those temporary files.

Stupid Is as Stupid Does

The whole process is frustrating. Unless you spring for Toast or a similar program, you can't simply copy an existing music or data CD from the original to a blank. The Mac OS and iTunes don't let you work that way. Everything has to go to the hard drive first, and files already on your hard drive actually get duplicated.

It just doesn't make any sense. Why can't the Mac OS simply duplicate a CD, just as the old Disk Tools used to let us duplicate a floppy? Why does the Mac OS have to duplicate files already on your hard drive before burning them? Why can't iTunes "unrip" MP3 files on the fly?

After all, Toast can do all of this and more, so it's not something Macs are incapable of doing.

Back to Random Access

Which brings us back to the question of hard drives, Zip disks, and MO drives vs. CDs and data tapes - random access vs. linear storage media.

Having made backup copies of nearly a dozen software discs in the past 24 hours, I find the whole process annoying. It doesn't have to be this inefficient.

Still, it does have to be inefficient. CDs are written linearly from start to finish, even rewritable ones. You can't simply append a file to a CD-RW on the Mac OS (although Windows users have software that allows it!); the whole disc must be rewritten.

Floppies, hard drives, Zips, and MO drives don't work that way. They all let you copy as many or as few files as necessary and do it in real time. None of this "copy it to the hard drive first, then write it, and then verify it" nonsense.

That means that Zips, MOs, and similar drives have a huge real world advantage over burning CDs. Data transfer rate aside, it's more efficient to only copy some files to your disk than to have to rewrite all of the data.

So why are Zips and MO drives so often bypassed in favor of CD burners? In part, it's because most people don't know that CD-RW really is a whole lot different from an oversized floppy. And in part it's because most computers today come with CD burners, so you don't have to buy anything extra.

Other parts: CD-R is cheap, usually well under 50¢ per disc in quantity. And CD is ubiquitous; even computers that can't burn CDs almost always have CD-ROM drives that lets them read CDs burned on other systems.

It's a darned inefficient system, yet just as VHS overwhelmed Beta and Windows dominates the personal computing market, consumers don't always pick the best technology.

And I'm a fine one to talk. I've never yet connected by USB Zip drive to my TiBook, and I don't have my SCSI Zip drive connected to anything right now, but I have made backup copies of 10 CD-ROMs in the past 24 hours....

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Dan Knight has been using Macs since 1986, sold Macs for several years, supported them for many more years, and has been publishing Low End Mac since April 1997. If you find Dan's articles helpful, please consider making a donation to his tip jar.

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