Outwardly, there's little to distinguish the Pi 2 from the Pi 1 Model B+, as it's now designated. At its heart, though, is the BCM2836, which according to Upton has been in development for a couple of years. It's "very, very similar" to its predecessor – the ARMv6-compatible BCM2835 – but with four cores and "a little tweak to allow us to address the gig of RAM," he explained.
The BCM2835, as used in previous Pis, is a Broadcom GPU – the VideoCore IV – with a single 700MHz ARM1176JZF-S application core glued in to run software. The system-on-chip is shipped with 256MB or 512MB of RAM stacked on top, less than the Pi 2's 1GB of RAM.