By now it seems that anyone with an engineering degree has probably read 2 or 3 teardown reports on Apple’s iPad. Few that I have seen so far talk about the DRAM memory subsystem – and that could be because the DRAM was hidden on top of Apple’s A4 processor.
Chipworks.com has torn down Apple’s A4 processor package and reports that the DRAM subsystem consists of two Samsung LPDDR1 1Gbit memories in package-on-package (PoP) configuration. The PoP allows for the DRAM to sit on top of the application processor and the whole thing has been marked on top with Apple’s A4 logo. There’s a great cross-sectional photo of the PoP system showing the A4 processor underneath and the two DRAM dice on top.