Editors' note: This article was originally published October 13. It has been updated throughout.
A teardown by iFixit and analysis by iSuppli, Chipworks and others reveal the iPhone 4S as a mini version of the iPad 2 in many respects.
Camera: A Sony CMOS sensor, according to Chipworks. Overall, camera is 8 megapixels, 60 percent more pixels than the camera on iPhone 4. A larger aperture (f/2.4) and new sensor. Better in low-light conditions. Video at 1080P, 30 fps.
Memory: The Apple A5 chip has 512MB of Samsung DDR2 RAM, according to iFixit's teardown. The capacity matches that of the iPhone 4 and iPad 2. Elpida (the merged memory operations of NEC and Hitachi) also supplies RAM for the 4S. The fact that the iPhone 4S still uses only 512MB "highlights the efficiency of Apple's iOS operating system compared to those of competitive smartphones, which use twice as much [memory]," according to iSuppli.
Battery: Apple has managed to boost the WHrs (watt-hours) slightly--by five one-hundredths of a WHr to be exact, according to iFixit. "Look closely... closer... there it is: an extra .05 WHrs in the battery over the iPhone 4!"--said iFixit. Talk time is improved on a 3G network for the iPhone 4S compared with the iPhone 4, iFixit writes--adding that there's 100 hours less standby time on the 4S. Just a couple of things to keep in mind.
Apple A5 system-on-a-chip (SoC): The A5 appears to made by Samsung and pretty much the same SoC that's in the iPad 2, according to Anandtech, which did a concurrent analysis of the iFixit teardown. "At a high level there aren't any surprises here, the A5 on the iPhone 4S is virtually identical to what was used in the iPad 2 - although running at a lower clock speed and likely a lower voltage as well," Anandtech said. Chipworks seems to agree.
Qualcomm: Qualcomm RTR8605 Multi-band/mode RF Transceiver. And Qualcomm MDM6610 chip. iPhone 4S merges the HSPA and CDMA radio capabilities found separately in the two previous iPhone 4 models into a single product, making it a world phone and usable on AT&T, Verizon, Sprint networks. Apple is able to offer this for the first time because of the humble RTR8605 transceiver, according to Wayne Lam, an analyst at IHS iSuppli.
Storage/NAND flash chip: A Toshiba 16GB multi-level cell (MLC) NAND flash memory chip, like that found in the iPad 2. MLC is typically less expensive than single-level cell (SLC) flash but not as fast.
Accelerometer: The accelerometer is the same device as in the iPad 2, according to Chipworks--the STMicroelectronics LIS331DLH. "The LIS331DLH is an ultra low-power high performance three axes linear MEMS accelerometer belonging to the 'nano' family, with digital I2C/SPI serial interface standard output," Chipworks said.
Gyroscope: An STMicroelectronics L3G4200D. Previously found in the iPad 2 as well, according to Chipworks.
Updated at 1:40 p.m. PDT: adding Qualcomm 3G chip and Flash memory bullet points.
Updated October 14 at 10:15 a.m. PDT: adding more Qualcomm chip data and camera bullet point.
Updated October 15 at 12:30 a.m. PDT: Updated throughout.