Thunderbolt 3: the future is here - today

Aug. 12, 2019

The history of PCs is a fascinating one – most notably in how it’s perhaps been the most visible reflection of Moore’s Law in action. Back in 1981, when the IBM Model 5150 was introduced, the Intel 8088 – running at 4.77MHz - was the processor of choice. Basic internal storage was 16K of memory, upgradable to 640K. Floppy disk external storage – in the form of one or two – was optional: the base unit shipped with a cassette drive. (It wasn’t until 1983 that the IBM PC XT Model 5160 was shipped as standard with an internal hard drive.) And: its only ports were for that cassette drive and a keyboard. If you wanted to actually plug in a monitor, you needed an expansion card.

Setting a trend

The Model 5160 set a trend, though. Already, a port had bitten the dust: the cassette port was no longer featured. Of course, that made sense: newer, improved technology had made it redundant. That’s long been the story of connecting external devices to PCs: there’s always been something better coming along.

Take the serial interface, for example, with its typical transfer rates of ~115K bits/second. Although serial communication is still widely used in industry – when did you last see a PC with a serial port? It seems those stopped shipping in around 2004. Then, there was the parallel interface with its whopping ~4Mbps – fast enough to drive not only large amounts of data to a printer, but also to the Iomega Zip Drive of blessed memory.

The advent of USB was something of a game-changer. It seemed to have everything going for it. Not only did USB 1.0 have a maximum speed of 12Mbps – it also looked like it was capable of being a universal interface for any kind of peripheral. (It still wasn’t fast enough for transferring video, which is why, for those who were into Adobe Premiere, a PC configured with a Firewire port was mandatory.)

Death knell

USB pretty much sounded the death knell for almost any alternative – and that included the PCMCIA and ExpressCard interfaces that were widely shipped with laptops. In fact: just like you can’t buy a PC with a serial (or parallel) interface any more, you can’t buy a laptop with PCMCIA or ExpressCard capability either.

Which, for many users of portable avionics devices, is a problem – because, historically, that’s been their connectivity option of choice.  Yes, there’s USB – which, in its USB 3.0 guise, is 1,200x faster than those old parallel ports - but for many applications, its latency is too variable. And, at an average of 30 microseconds, too high. Also: it doesn’t support hardware interrupts, DMA or PIO access.

But: just because we’ve got something newer and better doesn’t mean that what we have today has stopped working. Here, though, there’s another challenge. Recent government-mandated security requirements have presented a challenge to avionics interface customers that mean it’s imperative to upgrade to the latest operating systems – and the hardware platforms that support them. But: the latest hardware platforms don’t support PCMCIA and ExpressCard – and even USB 3.0 isn’t good enough for portable avionics applications.

Good news

There is, though, good news – very good news – in the shape of Intel’s Thunderbolt 3 interface. When Intel launched it, the company described it as “computer port nirvana”. Why? First, because it delivers bandwidth of 40GBps – four times the data rate of USB 3.1. How fast is that? Fast enough to download a 4K movie in 30 seconds. It uses the USB-C port – meaning it will work with almost any device. It delivers latency of less than a microsecond. Oh, and: it supports hardware interrupts. And DMA. And PIO access. What’s not to like? Thunderbolt 3 does almost anything you’d want an interface to do.

Imagine: the speed and features of bus-based – with the convenience of cable. And, as of today, Thunderbolt 3 is now available for even more Abaco portable avionics devices.

Abaco was first portable avionics device supplier to see the opportunity that Thunderbolt 3 presented for our customers. The launch of the RCEI-830A-TB  with support for ARINC 429, ARINC 615-3 dataloader, ARINC 717, ARINC 575 and selected 2-wire, 32-bit protocols and the QPM-1553-TB was followed today by  the launch of the  RCNIC-A2PA-TB for AFDX/ARINC 664 Part 7 protocol traffic applications and the RAR15XF-TB - the highest density portable MIL-STD-1553 and ARINC 429 device available.

If history is anything to go by, Thunderbolt 3 won’t last forever. But: just as with USB 1.0, USB 2.0 and USB 3.0, we can be confident that there will be successive generations of Thunderbolt technology – making it about as future-proof as an interface can be. When it comes to portable avionics devices, the future is here - today.

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