The disc drive is dead -- or it's at least issuing a triumphant death rattle.

Not in PCs just yet, but certainly in Apple's Macs. Earlier this week Apple introduced updated versions of its MacBook Pro with Retina Display, alongside an all new Mac Pro. What wasn't updated was Apple's line of non-Retina MacBook Pros, the only Apple devices that were still sporting a disc drive. In fact, Apple axed the 15-inch version and trimmed the non-Retina line to a single, 13-inch machine. The company has whittled away at product lines like this in the past, and it's usually a sign of imminent extinction.

All this started with the arrival of the MacBook Air in 2008. The specialty computer trimmed the MacBook Pro's inch-thick size by getting rid of the disc drive and many of the ports.

A high price tag kept most people from snapping up an Air over one of Apple's less expensive notebooks. But as time went by, slimmer, cheaper, and more powerful models came out, and it eventually replaced Apple's plastic MacBooks as the entry level notebook.

But rewind back to 2008, and Apple was making a gamble. It was a whole three years before the company would introduce its Mac App Store for distributing software -- both its own, and apps made by other companies. It was also years before some major third-party companies, namely Adobe and Microsoft, were pushing their biggest products as cloud subscriptions. Even Netflix's streaming service -- now used by more than 40 million subscribers worldwide -- was still in its infancy.

There were some stopgap measures though. One was a new feature built into OS X, Apple's desktop operating system, as well as a utility for PCs that let Air users tap a working disc drive from another computer using Wi-Fi. Apple also sold a standalone external disc drive for $79, as well as offering its OS recovery tools on USB sticks. Those USB dongles were later replaced by a recovery tool that could download a fresh copy of the OS over a broadband connection.

Apple wasn't the first company to exclude a disc drive from its machines, though Apple's move came at a time when many PC competitors were aiming to upgrade the disc drives on notebooks from DVD readers to drives that could read high-definition discs. For Apple, which was making an increasingly large amount of money selling movies and TV shows through iTunes, this never made much sense. Also, the battle between HD-DVD and Blu-Ray -- which were two warring hi-def disc formats -- didn't end until a month after the Air's 2008 debut. Some of the initial notebooks with those drives were not only big but also required high-end hardware that ballooned costs.

Hindsight is 20/20
The benefits of all this seem obvious. Since the Air, ditching optical drives has led to slimmer and svelter devices all around. Last year's iMac redesign was one of the most dramatic. By removing the drive and using new manufacturing technology, the once boxy machine was cut down by 40 percent. Its sides were tapered down into a 5mm edge, which is close to the thinnest part of the newest MacBook Air.

The same goes with the new Mac Pro, which Apple says is one eighth the volume of the previous generation. That change was not just the optical drive but changes to other components as well, like moving from hard drives to flash storage, and a redesigned cooling system that pulls air through a hollowed out central core. Like the original Air, all that comes at a price. The machine starts at $2,999, and a second, higher-end version runs $3,999.

The new Mac Pro is indicative of a direction Apple started back in 2008 but never quite perfected, which is offering future expandability on its nearly tinker-proof notebooks. That's not a new thing for computing, but it's been limited somewhat by the ports Apple's gone with. Many, like Firewire 800 and ExpressCard were offered up only on the higher end products, and phased out of the consumer machines.

That changed in 2011 when Apple started using Thunderbolt, a collaboration with Intel that combined DisplayPort technology with PCI Express. That consolidated ports to the point where Apple made a sister product -- its now languishing Thunderbolt Display -- that requires only one jack on a computer to supply it with an Internet connection, USB, and visual information. The only thing missing is enough power to run the computer, something that could change with future chips, and versions of Thunderbolt.

The next generation of the technology, Thunderbolt 2, is now starting to make its way into the Mac Pro and MacBook Pros, and promises even faster speeds. So as the disc drive has disappeared, Thunderbolt has flourished among Macs. PC makers, however, have opted for USB 3.0 instead.

The new Mac Pro: You have to see to believe (pictures)

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In hindsight, it seems painfully obvious that trimming drives, and thus size, would help other parts of Apple's business. Between making both its gadgets and its packaging smaller, the company can get more product to places in one shipment. For something like the iPhone (which, to be fair, never had a disc drive), that's resulted in a 60 percent increase in the number of boxes Apple can ship versus the one it made in 2007. That makes a big difference when those devices are being loaded into an airplane for a big launch, which can cost $242,000 a flight, according to a recent Bloomberg report.

The big question going forward is what else can be cut to trim size? Products like the iPhone and iPad have shown that something as basic as a keyboard or mouse pad can be successfully reimagined as one big screen. Perhaps just as big of a jump could happen with Apple's computers as well.