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Here’s a Twitter thread from a former Apple engineer: https://twitter.com/stuntpants/status/1346470705446092811 https://twitter.com/stuntpants/status/1346470705

Here’s a Twitter thread from a former Apple engineer: https://twitter.com/stuntpants/status/1346470705446092811 https://twitter.com/stuntpants/status/1346470705446092811 > arm64 is the Apple ISA, it was designed to enable Apple’s microarchitecture plans. There’s a reason Apple’s first 64 bit core (Cyclone) was years ahead of everyone else, and it isn’t just caches. > Arm64 didn’t appear out of nowhere, Apple contracted ARM to design a new ISA for its purposes. When Apple began selling iPhones containing arm64 chips, ARM hadn’t even finished their own core design to license to others. > ARM designed a standard that serves its clients and gets feedback from them on ISA evolution. In 2010 few cared about a 64-bit ARM core. Samsung & Qualcomm, the biggest mobile vendors, were certainly caught unaware by it when Apple shipped in 2013. > Apple planned to go super-wide with low clocks, highly OoO, highly speculative. They needed an ISA to enable that, which ARM provided. > M1 performance is not so because of the ARM ISA, the ARM ISA is so because of Apple core performance plans a decade ago.

klelatti 4y ago
Very interesting - many thanks! Edit: I’m a bit puzzled by the claim that Apple was selling Aarch64 before Arm had finished their first design - A7 announced at end 2013 but A53 appeared in 2012?
- NobodyNada 4y ago
  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. [0]: https://www.techspot.com/news/50656-arm-announces-64-bit-cortex-a57-and-cortex-a53-processors.html https://www.techspot.com/news/50656-arm-announces-64-bit-cor... [1]: https://en.wikichip.org/wiki/arm_holdings/microarchitectures/cortex-a53 https://en.wikichip.org/wiki/arm_holdings/microarchitectures...
  - klelatti 4y ago
    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.

klelatti 4y ago

Very interesting - many thanks! Edit: I’m a bit puzzled by the claim that Apple was selling Aarch64 before Arm had finished their first design - A7 announced at end 2013 but A53 appeared in 2012?

NobodyNada 4y ago
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. [0]: https://www.techspot.com/news/50656-arm-announces-64-bit-cortex-a57-and-cortex-a53-processors.html https://www.techspot.com/news/50656-arm-announces-64-bit-cor... [1]: https://en.wikichip.org/wiki/arm_holdings/microarchitectures/cortex-a53 https://en.wikichip.org/wiki/arm_holdings/microarchitectures...
- klelatti 4y ago
  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.