A nice approach I'm hoping will gain traction when discussing density across different types of logic is the "LMC" metric, as put forward by some TSMC and Stanford folks: https://ieeexplore.ieee.org/stamp/stamp.jsp?arnumber=9063714

Improved semiconductor device density directly translates into benefits for more advanced computing systems— the primary driver for progress in semiconductor technology. Thus, we propose the use of the following three-part number as a metric to gauge advancement of future semiconductor technologies: [DL, DM , DC ], where DL is the density of logic transistors (in #/mm2), DM is the bit density of main memory (currently the off-chip DRAM density, in #/mm2), and DC is the density of connections between the main memory and logic (in #/mm2). As an example, today’s leading edge technologies that are published in the literature [15]–[17] can be characterized by [38M, 383M, 12K]. As another example, 3-D stacking of multiple logic and memory dies can increase DL, DM, and DC .

I love the idea of having that information readily available, but I don't think it will ever be a banner spec. Three numbers is two too many and who wants "density" when you can have "MEGATRANSISTORS"? I know, I know, but marketing is what it is and I think it's better to lean into it.

Of course, and I agree that marketing traction matters. I should have said this is an idle hope that some of these fancier metrics get published/leaked about TSMC/Samsung/Intel processes rather than that they become the metric. I do think MT/mm^2 or whatever is a strong candidate to become the thing. "megatransistors" is an exciting word.

>> "megatransistors" is an exciting word.

Not as cool as megaFonzies.

So is that going to be M as 1000^2 or M as 1024^2.

(still bitter about the whole GB vs GiB think caused by marketing people)

To be fair to marketing people, they were correct, weren't they?

Deciding that in your field you're going to redefine standard units and their abreviations is a bit lazy.

That's "mega-transistors" per mm^2?

Perhaps it would be better to go with "6502s per square millimeter" or something like that that would probably be a closer approximation of real-world density, since it accounts for wire routing and so forth.

SRAM density is sometimes used I think.

Not folksy enough. Just like we use Libraries of Congress to measure information volume, we should rate our chips in terms of AGC/mm^2

(Apollo Guidance Computer)

Well, I would be just glad that at least it's not AGC/sq in

Today's chips have many more layers of interconnect than the 6502. Also the aspect ratios of transistors are different.

Isn’t that still a very bad descriptor though, like relying only on clock speed to make a decision? Though I guess many people do; back in the day, I think AMD cpus were on par with intel CPU’s running 200MHZ faster. But all people saw was AMD 1.7Ghz and intel 1.9Ghz. The result, the AMD chips at 1.7Ghz were called Athlon 1900. Which is the same thing as the equivalent feature length for FinFet. The people in the know should actively be discouraging reliance on single dimension (frankly misleading) terms.

Should that be future-proofed and be per mm^3? I was under the impression that designs are becoming more three dimensional.

According to the Bekenstein bound, the maximum entropy in a given region of space is proportional to the area of a surface containing that space, not its volume so to really future-proof it, we should probably go with per mm^2...

Maybe for memory, but I think it's too early for logic where heat transfer forces you to keep volume per surface area under control. Legitimate 3D logic will require a radically parallel compute model, probably something neural, and until we see what form that takes I think it's better to keep the metric 2D.