Changes

;CPU Processor Addressing - 32-bit | 64-bit

64-bit CPUs offer a significant leap over 32-bit CPUs. The main advantage is that 32-bit CPUs can only address 4GB of memory, whereas 64-bit CPUs can address 16 Exabytes of memory (far more than is currently physically possible in a modern PC). However, this is not the only advantage. Often overlooked is the fact that 64-bit CPUs have a more modern design, with a modern CPU instruction set. They can often perform the same tasks faster and more efficiently than 32-bit CPUs.

Macs first transitioned to use 64-bit CPUs with the PPC G5. There was no compatibility issue at the time, because the G5 had 32-bit backwards compatibility. But at the time IBM and Motorola (who designed and produced the PPC chips) had pretty much given up on the idea of producing desktop CPUs, so Apple had little choice but to transition to using Intel processors. Intel Core Duo processors at the time were much more power-efficient at the time, but they were 32-bit. So when Apple introduced Core Duo Macs, they sacrificed the advantages of 64-bit. This only lasted a couple of years, as the next generation of Macs shipped with Core 2 Duo CPUs, which were 64-bit. The next major event for Mac compatibility was the dropping of support for 32-bit x86 software in macOS 10.15 Catalina.