There is also a core for security in there somewhere running an L4 microkernel, as described in the security guide[1] page 7

[1] http://images.apple.com/privacy/docs/iOS_Security_Guide_Sept...

Wow, thats news to me. Its been there since the A7 apparently and is used to process the fingerprint sensor data:

"The Secure Enclave uses encrypted memory and includes a hardware random number generator. Its microkernel is based on the L4 family, with modifications by Apple. Communication between the Secure Enclave and the application processor is isolated to an interrupt-driven mailbox and shared memory data buffers.

Each Secure Enclave is provisioned during fabrication with its own UID (Unique ID) that is not accessible to other parts of the system and is not known to Apple. When the device starts up, an ephemeral key is created, entangled with its UID, and used to encrypt the Secure Enclave’s portion of the device’s memory space."

They found CPU, GPU and cache. What is in the remaining 40% of the chip? There are a lot of individual blocks in there.

A big part of what Chipworks does (as a company) is reverse engineering silicon from die shots and x-rays and such. They're not just going to hand this kind of information out on a platter - they were commissioned to do a cursory glance for this puff piece.

But it also doesn't take a genius to guess at what the various hardware modules do just given what the iPhone can do.

This is where Apple really adds value and why they have their own silicon design teams.

Some of the blocks:

-- M7 motion chip

-- Image processing chip to support camera

-- (I suspect) audio processing chip to do compression and feature extraction for SIRI

-- (suspect) video codec (though this may be done by GPU)

-- Secure Enclave -- CPU with secure data, random number generator, Apple Pay support, Fingerprint Sensor support

-- (I suspect) memory management units and io co-processors and the like that are too mundane to get much public mention

The motion chip is a separate package.

Chipworks decapped the M7 on the iphone5 and found it to be a custom model of the LPC18xx from NXP

http://www.chipworks.com/en/technical-competitive-analysis/r...

http://www.nxp.com/products/microcontrollers/cortex_m3/lpc18...

Hardware video codec support is almost always a seperate module, yeah, as are audio processing and video input/output.

Various units. You can get an idea looking at Snapdragon graph: http://www.gadgetfreak.gr/wp-content/uploads/2014/04/snapdra...

If these kind of raw IC photos interest you, here's a couple links describing what you're looking at:

"The 6502 CPU's overflow flag explained at the silicon level"

http://www.righto.com/2013/01/a-small-part-of-6502-chip-expl...

And a handful of links by other HN members about how to interpret silicon-level images:

https://news.ycombinator.com/item?id=7481973