I'm astonished that it works! To my understanding, the 128GB has specifications for how to "talk" to it on its datasheet and same with the 1TB. Do they have the same manufacturer for them to have the same pinout?
And, how come they're the same size lol. Intuitively, I'd expect the 1TB to be way bigger.
Generally most memory uses standardized physical/electrical/firmware interfaces from JEDEC, an industry consortium. I do not know for certain if the iPhone memory is standard.
Mobile RAM/Flash packages are usually made in larger capacities by stacking several dies within a package. This can involve die thinning - grinding the dies thinner so they fit within the same space after stacking.
1TB storage comes from another donor iPhone apparently so it makes sense it just fits and works. I guess Apple didn't think of matching them to specific motherboards so you can still reuse them
And, how come they're the same size lol. Intuitively, I'd expect the 1TB to be way bigger.