MacBook Pro m4 memory channels
Hi there, I’m interesting in what parts memory shares between channels on a new M4 chip?
24gb interesting and 48gb
is it 2x12 and 2x24 or how?
If you have studied RAM organization where the RAM is on replaceable DIMM modules, everything you learned about that design is wrong for the Apple-silicon MacBook Pro processors.
You should start your research reading about High-Bandwith Memory (HBM).
Apple opted to put the RAM chips directly on the system-on-a-chip. This removes many constraints that limited older RAM designs. Pathways to and from RAM memory can be VERY wide, and trace length does not get out of control, and there is no need for the extra-beefy driver circuits required in older designs.
Also multiple RAM chips may be stacked on top of each other, with connections running right through the sub-dies and connecting multiple devices. Remember that this RAM feeds Caches, which may be very wide at the incoming end and a different width when connecting to the compute processor or graphics processor.
I don't know of any Apple articles that discuss this in depth. Most readers here just want a fast computer to get their other work done. if you are studying computer architecture, there may be textbooks and web sites that discuss these sorts of architectural features in detail.
