Chips on a board. Kinda like ants on a log.

STMicroelectronics LIS331DLH (2233/DSH/GFGHA) ultra low-power, high performance, three-axis linear accelerometer

Texas Instruments 343S0628 touch screen SoC

Broadcom BCM5976 touchscreen controller

Rather than a single touchscreen controller, Apple went with a multi-chip solution to handle the larger screen size, à la iPad.

Apple A6 application processor

Qualcomm MDM9615M LTE modem

Qualcomm RTR8600 Multi-band/mode RF transceiver, the same one found in the Samsung Galaxy S III