And this is why it's really a desktop you can take away from your desk. The idea is that you have a powerful, capable system at your desk, but when you stand up to walk out, you can pinch out only the bare essentials of what you need to get stuff done on the go – and it's still your Mac, still the same machine. You don't have to muck about with syncing of files or having to install and configure apps on a desktop and a laptop system: your desktop is your laptop.
As well as the practical advantages of this, to me there's something just so awesome about slotting your laptop into a desktop case like this and having it be turbo-charged. The Duo Dock would draw the Duo in a bit like a VHS cassette, and there was even an eject button to spit it out again.
There were smaller, cheaper and more portable dock options too, but all worked through that PDS, which gave it full access to the Duo's CPU and data buses.
Answering the same questions again
Again, the reason such an over-engineered system was even necessary was because the limitations of technology wouldn't let Apple make a small, light laptop that was as powerful and capable as a desktop. While we've made great progress with laptops' capabilities, though, that's actually still a problem that affects us today. So here's how and why Apple could reuse its old idea today.
One of the obvious areas where laptops still lag is in graphics performance, and it's at least theoretically possible to use an external graphics card hooked up over Thunderbolt – in some ways a spiritual successor to PDS – so that's the first thing we spec into in our imaginary dock.
What's more, with an increasing reliance on GPGPU – using a graphics card for general computing tasks – a big, meaty dedicated graphics card in the dock to augment a battery-boosting weedy graphics card inside the laptop will boost overall performance too.
And while we're about it, let's hook up a load of internal storage as well. I'd love to see Apple put a Fusion Drive in place – a hard disk paired with a PCIe SSD, in this case inside the laptop – but leave additional bays for more hard disks. When you filled it up, you'd slot a new drive into an empty bay (a bit like the old Power Mac G5 or Mac Pro) but the clever bit is that the OS would take care of expanding the storage dynamically so you'd only ever see one drive. The speed of the SSD would keep everything fast and responsive.
When you undocked, the files on those hard disks would still be "there", just greyed out, and you'd use Apple's Back to My Mac tech seamlessly to pull it over the internet. The same tech that tells a Fusion Drive what files you regularly use in order to 'cache' them on the SSD means that you should have most stuff you actually need on the laptop's internal SSD anyway. The only difference from a Fusion Drive inside an iMac is that here the hard disk is external to the laptop (inside the dock, over a Thunderbolt bus) rather than internal alongside the SSD – something you can actually do yourself today if you want to.
Indeed, one of the internal bays could be used for a dedicated Time Machine backup drive that would also work over your local network or even the internet, CrashPlan-style, when you're undocked. And since we're wishing, let's finally make this the first Mac that has built-in 4G, so that the remote file grab thing works wherever you are. Of course, you'd have loads of ports for peripherals on this dock, all piped through the Thunderbolt bus, with its support for USB, FireWire, high-speed Ethernet and even displays.
You could imagine two dock designs, one a little box that would have these ports on it (including connections for two or three displays) or one which is essentially a big screen – not unlike an updated, beefed-up Thunderbolt Display – with all that included. You don't have to make it suck in the laptop to amuse and delight me, but you could. And boom: a slick, hugely capable and connected desktop computer, a subset of which I can pick up and walk out the door with, which is breathtakingly svelte and has truly epic battery life.
It might be that one day we can make a portable computer that packs the full power of a desktop – or a desktop that's entirely portable, which was a bit more like what the Duo was trying to do – and it might be that a connection to the internet becomes so fast, robust and ubiquitous that we dispense with the need for vast stores of data held locally on hard disks. That day is not today. Today we still need to compromise, which is why today is the day to resurrect the PowerBook Duo's clever compromise.
The 12-inch MacBook Air looks all very nice in those artist mock-ups, but Apple might do well to radically reimagine the very notions of desktop and laptop computers, rather than just refining, refining and refining again the same basic recipe for a laptop.
