[MrBuddyCasino]

> on chip memory is very very quick

It is not on-chip memory, the dies are separate, they're just in the same package. They seem to use standard LPDDR4 connectivity, so I don't think its actually faster. The "unified" bit seems to matter more: having a single address space for both CPU & GPU, but this is pure speculation. I don't know if AMD or Intel APUs do this too.

[alblue]

The fact they are on the same package means that the electrical signals have a lot less far to travel from memory to cpu, and therefore you don’t have the signal losses or interference from the board having to route memory lines externally.

As a result you would be able to drive a higher bandwidth because you don’t need to be as limiting with the transfer time of signals.

[MrBuddyCasino]

Or you could use less power for the same speed. Hard to tell what Apple did, without some detailed benchmarks. I suppose one could bench memcpy and derive the clock rate from that.

[Taniwha]

It's unlikely you're going to transfer data any faster - they're using commodity drams like anyone else - they will however be able to save a clocks's worth of latency here and there which is useful