The first product to feature the A4 was the first-generation iPad, followed by the iPhone 4, fourth-generation iPod Touch, and second-generation Apple TV.

The iPad (1st generation) was discontinued earlier than the iPhone 4 with the release of iOS 5.1.1 on May 7, 2012 because it only had 256 MB of RAM compared to 512 MB on the iPhone, and the fact that applications would crash more frequently with the graphics using a large portion of the RAM.

"[6] The A4 features a single-core ARM Cortex-A8 central processing unit (CPU) manufactured on Samsung's 45 nm fabrication process[7] using performance enhancements developed by chip designer Intrinsity (which was subsequently acquired by Apple)[8] in collaboration with Samsung.

[9] The resulting CPU, dubbed "Hummingbird",[10] is able to run at a far higher clock rate than previous Cortex-A8 CPUs while remaining fully compatible with the Cortex-A8 design provided by ARM.

The clock rate of the Cortex-A8 in the A4 used inside the iPhone 4 and fourth-generation iPod Touch is 800 MHz (underclocked from 1 GHz).