Back

For many of us it was the culmination of years of effort creating this chip and porting all of our software to it. I was working on the kernel and EL3 monitor. When we started we had no compiler, no assembler, no debugger, and really no documentation and the ISA still in flux. Someone wrote a macro-based assembler. Code gen bugs were a huge problem as clang was adding support. LLDB never caught up so someone on my team did a port of GDB.

I skipped thanksgiving vacation 2012 because FPGAs were coming in. We were booted to Springboard in about a week, the result of a huge amount of preparation in simulation. The first tapeout booted in one day. I remember talking to an Arm engineer about that time and was not allowed to say where we were, but gathered their core was still purely software simulation.

When iOS shipped, it was a full 64-bit native release. There was no 32-bit code in the OS image* (including complicated things like the Safari JavaScript engine). Everything was ported day one.
*except the bits required to support 32-bit third party apps

The reception was very confused. Most of the tech pundits didn’t understand why a phone needed a 64-bit processor. They mostly focused on the ability to have more than 4 gigs of memory (5S had 1gb). When they got it in their hands they knew. Apples first core, Swift, was released in the previous year and it was a perf leader. This chip was much faster than that, it was an insane leap that put Apple 3-5 years ahead of the rest of the industry.

My favorite quote:
“I know there's a lot of noise because Apple did [64-bit] on their A7," said [Qualcomm senior vice president and chief marketing officer] Anand Chandrasekher. "I think they are doing a marketing gimmick. There's zero benefit a consumer gets from that."
"Predominantly... you need it for memory addressability beyond 4GB. That's it. You don't really need it for performance, and the kinds of applications that 64-bit get used in mostly are large, server-class applications," said Chandrasekher.