Slots on your Mac can offer various types of expandability
The Mac Pro is the most expandable of any Mac model, and while not available for sale anymore in Europe as of March 2013, plenty are still in use in professional settings because of the system's massive horsepower and extraordinary flexibility - it's Apple's heaviest iron.
The Mac Pro can accommodate four PCI Express expansion cards (one is already occupied by a video card). PCI Express is a widely adopted standard in the PC world, so many manufacturers make cards, but only some offer Mac-specific cards or Mac drivers to enable them to operate.
Cards available for the Mac Pro include exotic high-speed networking technology like Fibre Channel, or external SATA (eSATA) - a faster hard disk interface than FireWire. Professional digital video companies manufacture specialty cards to enable the Mac Pro to input and output broadcast and cinema-quality video, which can take up massive bandwidth. There are also USB 3.0 cards; while it's become standard issue on other Macs, USB 2.0 is all that the Mac Pro includes from the factory.
Some Mac Pro owners have maxed out the number of internal drives their systems can handle (there are four bays, each capable of supporting a 3.5-inch drive). For those users, adding additional SATA expansion cards can be handy, especially if it's time to start incorporating SSDs in the mix. Put in an array of SSDs and you can set them up as a RAID for even faster performance.
The now-defunct 17-inch MacBook Pro, which went out of active circulation in June of 2012, was the last MacBook Pro to feature an ExpressCard/34 slot - an expansion slot that offered PCI expansion capabilities. Cards available for the MacBook Pro include FireWire 400 and 800, eSATA, USB 3.0, additional Gigabit Ethernet ports and more.
How fast can a Mac go?
Replacing hard drives with SSDs, adding memory and fine-tuning the software contents of your system are all fine ways to improve the performance of your current Mac, but how fast will the Mac get?
From processor improvements to bus speed changes, different types of data storage and more, let's take a look down the road.
Let's start with Wi-Fi. All of Apple's currently shipping products use 802.11n technology, which can transfer data - in theory - at up to 300 megabits per second (Mb/s). Routers are already hitting the market that support the fifth generation Wi-Fi spec, called 802.11ac. 802.11ac can transfer data at up to 1 gigabit per second, and the industry anticipates widespread adoption by 2014. (The routers available today are only using a preliminary version of the 802.11ac spec, and no Macs support it natively yet; tread carefully.)
There may be a reason to postpone your purchase of any 802.11ac networking gear, at least for a bit. Another wireless networking technology called 802.11ad is coming in fast behind 802.11ac. It'll work at up to 7Gb/s, with backwards compatibility for older, slower systems.
Of course, not everything can be wireless - sometimes you still need a good old fashioned cable to connect peripherals to your Mac. To that end, the current state of the art is USB3, which can transfer data at up to 5 gigabits per second. At CES earlier this year, the USB Promoter Group announced a new USB3 enhancement that doubles USB3 to 10 Gb/s instead. That puts USB3 on a similar level as the transfer speed of a single lane of Thunderbolt (Thunderbolt actually uses two lanes, with effective bandwidth of 20Gb/s).
Thunderbolt isn't sitting still, either. It's due for an overhaul late this year, when Intel introduces new silicon that will double the effective bandwidth of Thunderbolt from 10 gigabits per second, per lane, to 20Gb/s per lane. Chips featuring the new 'Falcon Ridge' controller are expected to be widely available in 2014. And Intel says there's plenty of room left to grow Thunderbolt even further.
Serial ATA (SATA) is the interface Macs use as the hard drive or SSD interconnect. In its current form, SATA 3.0, the interface can transfer data at up to 6Gb/s second. SATA was designed at a time that mechanical hard disks were still state of the art, however, and times have changed. Some higher-performance SSDs are already hitting the limit of SATA 3.0 interface, maxing out that 6Gb/s speed limit.
But relief is in the works, according to the Serial ATA International Organization. SATA Express, officially announced at the CES trade show in Las Vegas, Nevada earlier this year, is a recently proposed spec that will up the speed limit even more. The organisation says that SATA Express will be able to move at up to 16Gb/s.
SSDs aren't the be-all end-all of storage technology, either. Already a company called Everspin is selling 'Spin-Torque Magnetoresistive Random Access Memory' or ST-RAM, a non-volatile solid state storage medium that it says is 500 times faster than current SSDs. The downside, predictably, is price - currently ST-RAM costs about 50 times more than SSD, and SSD is no value compared to a cheap, old-fashioned hard disk drive.
Looking much further down the road, researchers are working on holographic data storage. This optical storage medium stores data in three dimensions instead of two, such as on a DVD or Blu-ray disc, which increases the storage density of the material dramatically.
Genetics researchers have also tested the viability of using DNA as a storage medium, though they admit they're decades away from having real working storage systems available. And IBM is working on storage systems that record data at the atomic level.
Macs will, predictably, add horsepower through improved processors. The next jump in Intel hardware is making its way into the world now with the introduction of Haswell microprocessors, which replace the Ivy Bridge processors used throughout Apple's Macintosh product line today.
Intel's longer-term roadmap calls for continued refinements in processor architecture and a reduction in die size, allowing for ever more complicated processors that gradually grow more power-efficient. While Intel hasn't outlined all of its plans, we can count on chips with even more cores capable of multiprocessing capabilities well beyond what the CPUs in Apple's machines do today.
Ultimately, Haswell will be supplanted by Broadwell, Skylake and Skymont processors through 2017. Intel CEO Paul Otellini believes that silicon, the material that serves as the base of all current CPU designs, is probably in its last decade of use.
Intel hasn't said what it will replace silicon with, but if IBM's research is any indication, carbon may be a safe bet. IBM researchers have built circuits out of graphene, a highly conductive one-atom thick sheet of carbon molecules. It's possible to build much smaller, more powerful chips using graphene.
Gazing further into the future still, physicists have hypothesized about the feasibility of the quantum computer - a computer that stores data using quantum bits, or 'qubits,' instead of the regular binary bits (0s and 1s) that comprise today's machines. Qubits make it possible for quantum computers to work potentially millions of times faster than today's machines.
Quantum computers aren't a pipe dream. In fact, they've been produced in laboratories since the late 1990s. And one company, D-Wave actually makes what it says is a commercially available quantum computer, a 128 qubit system priced at US$10,000,000.
Clearly, some of this stuff is years away from finding its way into the Mac. But a lot of this technology is just a matter of time. What's for sure is that Apple will keep Macs performing as fast as possible, as soon as it reasonably can. We can't wait!