Originally Posted by wizard69
In this case Crystallwell is effectively a high speed cache chip. This isn't the same thing as system memory but the impact on performance is due to it being faster than DDR3 RAM.
True, but I view it as more of a semantics game. A computing system has pools of memory with the smallest, but fastest pool closest to the CPU logic. The pools get bigger, but slower the further away they get from the CPU.
Storage, as in HDD and SSD storage, is memory. It is a lot further away from the CPU, but is ~10 times bigger than system memory (RAM). They effect the performance a computing system as anyone who's done an upgrade from an HDD to an SSD will attest. Heck, the "cloud" is another level memory available to you, and obviously it's slow, but faster access to the cloud will come to play as more and more data is stored there.
With higher transistor densities, all these levels of memory get closer and faster access to the CPU/GPU. Like L2 cache, the memory controller used to be off-die, and it is now on-die. (Intel implemented some MCMs with Atom where the PCH/MCH was on-package, but not on-die I think, so they went through that stage too). I/O controllers used to be off-package, now they are on-package or on-die.
The modern Mac has basically moved as much of the memory access and memory levels closer to the CPU/GPU then ever before for PCs. L3 cache on-die. Memory controller on-die. SSDs connected by way of PCIe I/O that's on-die.
Apple iPhone SoCs have RAM that is on-package. If Apple made CPU/GPUs for their Macs, I bet, like you, a lot that RAM for some of their systems would be on-package sooner rather than later. But they have to wait on Intel.
Lastly, storage will eventually be on-package as well. A triple stack of chips in the package where the CPU, GPU, higher levels of cache, memory controller, I/O (including SSD controller) all in one chip. RAM chips on top of that, then SSD Flash chips on top of that; with, the hottest chips closest to the surface.
If you look at the Watch S1 "computer-in-package", they are almost all they way there. It's a PCB with a multitude chips, so it's more of a miniature logic board instead of an MCM, but the whole thing is encased in some kind of resin, and in effect, appears to the lone "package" in the system. I can see them maintaining the interfaces and shape of it so that Watch upgrades will become easy. 4 years down the road, the thing will have 2x to 4x the CPU, GPU, memory, storage, and radio performance, in the same basic "package".
If they start moving that type of design (encase the PCB in resin) to iPhones, hmm...
What I find shocking (if that is the right word) is that 128 MB of Cache RAM is more memory that some of my first few computers had altogether. The industry certainly has come a long way in one lifetime.
Yup. I feel old, and I don't think I'm that old. Way back, "storage" used to be mobile and we carried it around with us.