Microchip analyst Chipworks has confirmed that the A5 processor of the iPhone 4S is made by Samsung, Apple Inc.'s supplier-turned-legal adversary.

The reverse engineering specialist verified the manufacturer of the Apple-branded system-on-a-chip in a teardown of the gadget, according to Chipworks product manager Jim Morrison.

The iPhone 4S' A5 is a 45-nanometer dual-core part, virtually the same as the chip used in the iPad2, CNET.com quoted Morrison as saying.

The A5 contains a system memory also made by Samsung, according to consumer electronic repair guide iFixit in its own teardown of the iPhone 4S.

The teardown revelations support analysts' observation that Apple cannot instantly dump Samsung for another semiconductor supplier despite their patents disputes. But this is only as far as A5 is concerned.

With the ongoing legal tussle between Apple and Samsung, analysts see the manufacture of future iPhone processors being migrated to Taiwan Semiconductor Manufacturing Company (TSMC) and Intel.

There are reports saying TSMC will supply the smaller A5 for Apple's iPhone 5 and the A6 for the iPhone 6.