

Dissection of the Apple A4 - icco
http://www.ifixit.com/Teardown/Apple-A4-Teardown/2204/1

======
grinich
256 MB of RAM. Same as iPhone 3GS.

    
    
        This is the SDRAM inside the A4. 
        Yes, that's a Samsung logo. No, 
        that doesn't mean Samsung designed 
        the A4—just the RAM.*
    

<http://s1.guide-images.ifixit.com/igi/i41Jh6tuFo6RFBVE.large>

There's also a great side-cutaway shot, showing the 2 RAM dies.

<http://www.ifixit.com/Misc/iphone_processor_crossection.jpg>

~~~
pavs
Wow only 256MB RAM? Anyone else surprised?

~~~
rbanffy
Not at all. This thing runs a slim Unix-based embedded OS. Why would it need
more memory?

I use a netbook with 1.5 gigs and a non-slim Unix-like OS with X and Gnome on
top of it and it rarely hits swap.

------
andrewcooke
this doesn't actually tell you anything about the processor, just that it's in
the package, under two ram dies, and that it's single core "so must be an a8".

~~~
acg
It tells you more than that: it's not an A9 and does not contain a GPU. So
doesn't it dispel some rumours? What did you expect?

~~~
hga
No, it just asserts that because there's only one core it has to be an A8
(superscalar, no provision for SMP) not an A9 (out-of-order speculative issue
superscalar, single core and 1-4 cores SMP versions).

------
Arubis
I'd love to see a full layer-by-layer teardown of the actual die. Multi-die
packages are nothing special. Getting past metal8, even it it means going
straight to silicon, would let you pick out individual blocks.

------
bmalicoat
Why are wafers round? Is there a part of the process that requires spinning
the wafer?

~~~
jlangenauer
I believe its because the wafers are actually sliced of a single large crystal
of silicon, which grows in a circular cross-section.

<http://en.wikipedia.org/wiki/Wafer_(electronics)>

------
kristianp
I bet reverse engineering is against the license agreement.

------
ahi
anyone know how much this process costs?

~~~
hga
Enough that they didn't pay to have the metal layers "peeled off" one by one
(or just all of them as Arubis suggests) so that we could start to guess what
it really is....

~~~
Arubis
The consumables involved in stripping off metal and oxide layers have a
negligible price point. Most of the cost is engineer time, though how much
depends on what equipment/techniques are used (liquid chemistry, manual
polishing, plasma processing, etc.).

This isn't the case with all circuit forensics techniques: once you start
loading parts into more expensive equipment (even electron microscopes) you're
paying for tool time to offset training and tool value depreciation.

I know that's not really quantifying things, but that's something you'd have
to get from the lab that actually performed the work.

EDIT: if it helps, the actual process of removing a metal layer and an oxide
layer varies with the process, but would generally take under an hour (and
usually well under). There exist techniques to skip all that and go straight
to silicon significantly faster, though as these are all destructive
processes, you lose the ability to go back and see what was there before.

