It looks like A53 was announced in October 2012, but I’ve found no indication of whether the design was actually finished by then [0]. And remember that ARM just sells IP and other companies are responsible for manufacturing it; it doesn’t look like anyone actually produced A53 cores until 2015 [1] — whereas Apple was shipping actual consumer products with A7’s in them by October 2013.
Very fair point. OTOH there was a lot of detailed info on the A53 available in 2013 and SoCs were being announced with it.
I suspect this thread may be slightly exaggerating the position but certainly the case that Apple were well ahead of all the competitors - and no doubt they were deeply involved in the ISA design.
[0]: https://www.techspot.com/news/50656-arm-announces-64-bit-cor...
[1]: https://en.wikichip.org/wiki/arm_holdings/microarchitectures...