dumb peripheral question: memory as a circuit would seems easy to add directly on-chip for a company like Apple. Is that blocked by time-frame, IP, technology, cost?
dumb peripheral question: memory as a circuit would seems easy to add directly on-chip for a company like Apple. Is that blocked by time-frame, IP, technology, cost?
Logic gates and memory bits have very different fabrication processes (mostly because DRAM is optimized for a high density of big capacitors doing the storage).
You can put some memory on the logic wafer (SRAM) but it's area inefficient, which is wasteful on your expensive N2 wafer. So a dedicated DRAM process is vastly cheaper per bit, even at current elevated prices.
My guess is area becomes problematic. Chip becomes bigger, harder to manufacture without defects, costs rise as a result of those defects.
Bonus though, Apple is using "defective" chips in other products now such as the Neo which will help some with costs, but overall, you can't just add memory to the chip because the chip can become very yield sensitive, the process has to be there to produce the yield effectively.