The biggest difference is that in the M1, the memory is a part of the M1 architecture itself. There’s no memory slot or slots on the motherboard of an M1 Mac, nor is there an area where a memory chip has been permanently soldered on. Instead, the memory is integrated into the same package that contains the M1 itself.
Think of the M1 as a mini-Mac inside your Mac, with all of the major internal components, minus the battery, built into this mini-Mac. That’s the M1 — the System on a Chip. And because it’s all housed in the same small space, it’s faster and more energy efficient than the “traditional” way of spreading it all out across a motherboard.
The M1 processor’s memory is a single pool that’s accessible by any portion of the processor. If the system needs more memory for graphics, it can allocate that. If it needs more memory for the Neural Engine, likewise. Even better, because all the aspects of the processor can access all of the system memory, there’s no performance hit when the graphics cores need to access something that was previously being accessed by a processor core. On other systems, the data has to be copied from one portion of memory to another—but on the M1, it’s just instantly accessible.
This is why I have no reservations on buying an M1 MacBook with 16 GB of RAM — Apple’s been doing this for years on the iPhone and iPad. Flagship Android phones ship with expensive amounts of RAM — 12 GB or more — because they genuinely need this much spare memory for swapping between apps and tasks. Apple’s been selling iPhones with 3 GB of RAM that have been outperforming these Android phones for years, and that is due in no small part to the A-series chips in those devices. And this is the same technology now being used in the M1 (and soon to be M-series) chips.
Snell says, “The old way of thinking of RAM is dead.” And he’s right. RAM used to be something we just kept throwing into computers to get them to do more, but Apple’s way of integrating the CPU, RAM, GPU, and everything else is going to mean faster, cooler, and probably someday cheaper systems.