The exact genesis of the smartphone is open to debate, not least because the term itself did not enter widespread usage until 1997, but for many the IBM Simon was the first ever smartphone, combining a phone and a PDA for the first time in a commercially available device. And that makes yesterday the 20th birthday of the smartphone.

The Simon Personal Communicator was a handheld, touchscreen phone and PDA designed by IBM and built by Mitsubishi. The prototype of the device, code named "Angler" was first shown of the COMDEX trade show in Las Vegas on November 23rd 1992. Simon was something of a brick, measuring 200 x 64 x 38 mm, and weighing 510g.

The operating system was Datalight ROM-DOS running on a 16Mhz, 16-bit, x86 compatible processor. Other specifications included a 4.5 inch monochrome back-lit LCD display, 1MB of memory, a type PCMCIA card slot, a 9600-bps Group 3 fax, and a 2400-bps modem (0.00228 Mbps). The device was available on BellSouth Cellular for $899 with a two year contract.

The specifications of the IBM Simon may not match up to the modern smartphone, but, at a high level, it is clear there's a lot of similarities. The overall form factor isn't that different to what we have today, and the touchscreen was the primary input mechanism. The IBM Simon was even capable of running third party apps, although admittedly there was only ever one aftermarket third party app made available (DispatchIt), and it cost $299 (plus $2999 for the obligatory host PC software).

What has changed is the number of technologies included, or converged into, the smartphone. But even more notable is the number of smartphones being sold. The IBM Simon sold 50,000 units over the six months that it was available. This year smartphone sales are expected to top 650 million units.