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> Historically, almost all attempts to replace an enormously successful product line with something incompatible have failed. Except AArch64, which has a legac
by pcwalton 10y ago
> Historically, almost all attempts to replace an enormously successful product line with something incompatible have failed.
Except AArch64, which has a legacy 32 bit mode for compatibility but is otherwise a totally separate ISA, unlike x86-64 and i386.
- StillBored 10y agoAarch64 looks at first glance to be pretty dissimilar, but if you consider that its really a follow-on to THUMB2 it doesn't look as foreign. Also a lot of things appear different at first glance but aren't because they have basically been renamed. one example CPUID->MIDR http://infocenter.arm.com/help/topic/com.arm.doc.ddi0432c/Bhccjgga.html http://infocenter.arm.com/help/topic/com.arm.doc.ddi0432c/Bh... https://developer.arm.com/docs/ddi0500/f/4-system-control/45-aarch32-register-descriptions/451-main-id-register https://developer.arm.com/docs/ddi0500/f/4-system-control/45... The memory model is the same.. etc, etc, etc.