[PowerfulWizard]

Yeah, I'm looking at the rationale for HBM which looks physically similar and it seems to be closeness and the ability to have more wires.

https://en.wikipedia.org/wiki/High_Bandwidth_Memory

But the HBM photos have the 'interposer' layer and look to be using bare dies, the M1 looks to not have the interposer and to be using the DRAM package. I'm not fully convinced with why the DRAM needs to be on the M1 but there must be a reason. Apple's marketing site says their 'Unified Memeory Architecture' uses a 'custom package' so maybe the DRAM package appearance is the same but the interface is not.