Apple’s iPhone 4 became the first iPhone to use an Apple-designed A-series system-on-a-chip, the A4, in 2010.
The A4 integrated a processor and other key functions into one chip and was used in the iPhone 4, the first-generation iPad, and the fourth-generation iPod Touch. Apple’s move toward custom silicon gave it greater control over performance, power use, and product integration.
The A4 was manufactured by Samsung and used an ARM-based CPU design licensed through ARM Holdings, so Apple did not fabricate every part of the chip itself. Later A-series generations powered iPhones with increasingly capable custom CPU and GPU designs. This distinction matters: designing a chip, licensing an instruction set, and manufacturing silicon are separate parts of the semiconductor industry.