The A5 processor at the heart of the iPhone 4S is made by Samsung, according to a chip analysis firm, putting an end to speculation that Apple had gone elsewhere for its core silicon.

Chipworks, a firm that specializes in reverse engineering and

patent infringement analysis of semiconductors and electronic systems, verified today that the A5 chip is manufactured by Samsung, according to Jim Morrison, a product manager, who spoke to CNET today. The iPhone 4S’ A5 is a 45-nanometer dual-core part, virtually the same as the chip used in the iPad 2, said Morrison.

The Apple-branded A5 is a system-on-a-chip (SoC) that includes the main processor, graphics silicon, and system memory (RAM). In fact, the RAM is also made by Samsung according to iFixit. Though Japan-based Elpida also supplies RAM in some cases.

Taiwan Semiconductor Manufacturing Company (TSMC) had been cited as a candidate to make future Apple SoCs, possibly as early as this year. Speculation about TSMC ramped up when news of legal squabbling between Samsung and Apple intensified.

But switching manufacturers for such a critical piece of silicon can be fraught with danger, according to Ashok Kumar, an analyst at Rodman & Renshaw, who formerly worked at Intel. And a report this week claimed that Samsung may also be in line to make Apple’s upcoming A6 chip, which is thought to be a quad-core design.

Intel would be the ideal chip manufacturer–or so-called “foundry”–for Apple. Intel is a U.S.-based company and possesses what is probably the world’s most advanced manufacturing and chip technologies, including 3D transistor tech that will appear in Intel’s next-gen Ivy Bridge processors.