Hmm. The M1 is about 120 sq mm, substantially smaller than many Intel designs. The current estimate for 5 nm wafers is about $17K (almost certainly high). A single 300 mm wafer is about 70,700 sq mm. If we get die from 75% of that area, that gives us about a $38 raw die cost. Even with packaging and additional testing, I suspect they would be competitive.
Nice back of the envelope calculation. I think I'd add yield to it though.
TSMC had a 90% yield in 2019 for a 18mm2 chip[1]. Assuming a 120mm2 chip would have more defects, and assuming process improvements since 2019, maybe 80% would be an accurate-ish estimate.
Found an even better number, [2] list the defect rate as 0.11 / 100m2 => 87%.
That's a fair point, yield has to be included. I lumped yield in with the pessimistic 75% factor for area utilization of the wafer. I should have been more clear. The area loss for square die on a round wafer should be much less than 25% of the total wafer area.
If you look at process tech cost trends, the $17K is also very pessimistic. I think a customer the size of Apple is probably getting a much better rate than that. Remember, they sell well over 200 million TSMC fabbed chips a year. Hard to know for sure of course, but I imagine these chips are ultimately costing Apple well under $40. We'll never know of course...
The big skew in availability between 8GB and 16GB models implies to me that yields of perfect chips are lower than Apple expected, with too many ending up in the 8GB bin.
I came to the opposite conclusion. I think most users than expected paid for the 16GB models, leaving extra inventory of the 8GB modules. During black Friday/Cyber monday I saw several discounts on 8GB M1 systems, but none on the 16GB systems.
Hopefully that sends a message to apple to build systems with more memory. Seems insane to invest in a expensive M1 system (once you add storage, 3 year warranty, etc) and get only 8GB. Even it works well today, with a useful life of 3-6 years seems likely the extra 8GB will have significant value over the life of the system... even if it's just to reduce wear on the storage system.
That would imply that the M1 has the DRAM rather than just the controllers on the chip but all of the coverage I've seen says that they are separate chips in the same package.
