Brian's Brain

This post is an addendum to my Prying Eyes teardown piece, 'Studying The Second-Generation Apple iPod Touch', which went live on the EDN website at the end of September and also appeared in abbreviated form in the November 27, 2008 print edition.

When in my writeup I pointed out the 'Apple-marked ARM CPU-plus-DRAM, two-die, single-package stack, likely identical to the one in iPhones,' I meant 'identical' in the functional sense, not necessarily from a performance standpoint. I suspected, in fact, that Apple might have put a lithography-shrunk and slower-clocked version of the iPhone's Samsung-developed processor in the iPod touch as a cost-savings move, no matter how this divergence might complicate developers' desires to create one-size-fits-all applications that universally ran on all iPod touch and iPhone platforms. And one week later I thought my suspicions had been confirmed.

A music creation application co-developed by Brian Eno, called Bloom (iTunes link), appeared on the iTunes Store on October 9. When I downloaded it I discovered that it was plagued by a constant crackling sound. User and developer feedback, presumably derived from similar past experiences with other programs, suggested that the crackle was symptomatic of the application 'maxing' out the CPU...and that neither the first-generation iPod touch nor either iPhone generation exhibited it (version 1.01 of Bloom, released several weeks later, fixed the crackling issue). I was therefore surprised to learn last week that the 2^nd-generation iPod touch seemingly uses a processor running at faster core and frontside bus speeds.

The CPU used in the first-generation iPod touch and both generations of the iPhone is commonly believed to be a derivative of Samsung's 90 nm-fabricated S3C6400, running at a 412 MHz peak core frequency with a 100 MHz frontside bus and Imagination Technologies PowerVR graphics IP onboard. Conversely, the CPU in the second-generation iPod touch appears to be a variant of Samsung's 65 nm lithography-based S3C6410, running at 532 MHz with a 133 Mhz FSB. Comparative verbage (particularly check out this PDF link) also points out a number of functional enhancements to the S3C6400 versus its S3C6410 predecessor.

In the absence of official confirmation from Apple and/or Samsung (don't hold your breath on that, folks), this is all speculation, of course. But the evidence seems to be quite definitive.

p.s...in other iPhone and iPod touch news, hackers have succeeded in booting Linux on the platforms...