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> Today’s state-of-the-art is five-nanometre chips (though “5nm” no longer refers to the actual size of transistors as earlier generations did). It's refreshin
by lwneal 6y ago
> Today’s state-of-the-art is five-nanometre chips (though “5nm” no longer refers to the actual size of transistors as earlier generations did).
It's refreshing to see this mentioned. I'm no semiconductor expert, but it seems weird to me that although node size is measured in a physical unit, nanometers, it does not correspond to any real measurement that exists [1]. Each transistor in a 5nm chip is actually between 28 and 36 nanometers in width. It's called 5nm because of a theoretical calculation based on transistor density [2].
If Tesla advertised a new "200kWh" battery, I would be very disappointed if it turned out that the battery only held 95kWh, but the marketing department had decided that improvements in the charging network have made it "like 200kWh" compared to earlier models.
[1] https://en.wikipedia.org/wiki/5_nm_process https://en.wikipedia.org/wiki/5_nm_process
[2] https://en.wikichip.org/wiki/technology_node#Meaning_lost https://en.wikichip.org/wiki/technology_node#Meaning_lost
- xxpor 6y agoI feel that stuff like this has a long history in engineering. It's like how TVs are in the 55 in "class", or a 2x4 is actually something like 1.75x3.5 now.
- joshualross 6y agoI don't think we should limit to just engineering; you see this stuff in media, politics, finances, statistics, etc. Anything that is not well understood by the public at large is ripe for misuse.
- wfleming 6y ago2x4s are 2x4 before they're seasoned, though. The lumber is dried after dimensioning and shrinks as it loses moisture. But we still label it by the original dimensions because lumber is priced by the board foot (which is itself a weird archaic measure) of the lumber when it was cut. For comparison, sheet goods aren't priced this way. A 3/4" sheet of plywood really is 3/4", because the plywood was manufactured that way and as a manufactured product there is no seasoning. You're not being ripped off because a 2x4 is actually smaller. A sawmill had a tree, and they cut off a hunk of that tree, and they charge by how much wood they cut off. The dimensions of that piece of wood changed after they cut it (which in and of itself is a service they provide - it would be a hassle if you had to buy green lumber and dry it yourself).
- peteradio 6y ago2x4 in old houses will measure 2x4 and is "rough cut". Modern milling will turn rough cut true 2x4 into the clean cut "2x4" you use today by running them through additional planing process. I don't think any shrinkage is significant though. 3/4 plywood will measure less than 3/4.
- HideousKojima 6y ago3/4 inch plywood is usually actually about .7 inches
- wfleming 6y agoDoes this vary more depending on the plywood grade, maybe? I have some shelving I made from AB birch, and it looks pretty close to .75. Maybe 1/64 scant. (Although I don't have calipers handy and just used a tape measure, so I'm not being super precise.)
- spenczar5 6y agoLots of plywood, especially birch, is metric-sized. You might have 18mm plywood on your hands, which would be about 1/32 under 3/4 inches.
- neogodless 6y agoThe plywood I often buy at a big box home store is labeled as 23/32" (0.71875" or 1/32" less than 3/4") and it is actually that thickness. I don't recall seeing any 3/4" labeled plywood though.
- highfreq 6y agoI work in sawmill technology. Way back in history 2x4 were cut to 2" x 4". In a modern sawmill 2x4s are never cut to 2" x 4". They are cut to a thickness and width such that given saw deviation, and variable drying shrinkage nearly all boards will cleanly plane down to 1.5" x 3.5". The exact target dimensions will depend on how well the mill can control their saw deviations and the statistical range of shrinkage they expect for the wood they are cutting. Reducing dimension targets by controlling saw deviation and understanding drying shrinkage is a big part of sawmill efficiency and profitability.
- gumby 6y ago"Building" (or worse "designing") a computer is assembling lego bricks. Serious language inflation.
- taneq 6y agoYeah, these casuals think they're building a computer when they're really just sticking ICs together. If I was building my own computer, I'd do a real DIY build and start by creating the universe.
- HPsquared 6y agoIt's not new: CRT TVs and monitors were marketed by the size of the tube, rather than the size of the visible part (the screen itself).
- tedunangst 6y agoAnd a 16oz iced coffee from Starbucks doesn't contain 16oz of liquid!
- jjoonathan 6y agoOn the plus side, MT/mm^2 seems to be gaining steam as a metric. It removes one dimension of cheating and has the whole "bigger is better" thing going for it.
- deleted 6y ago[deleted]
- elihu 6y agoThat'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.
- amelius 6y agoToday's chips have many more layers of interconnect than the 6502. Also the aspect ratios of transistors are different.
- function_seven 6y agoNot 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)
- smnrchrds 6y agoWell, I would be just glad that at least it's not AGC/sq in
- acidbaseextract 6y agoA 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 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 .
- emteycz 6y agoRemember when Mercedes E230 meant 2.3 litre engine? I feel this is similar. Indeed a long history as another commenter points out.
- noncoml 6y agoYup. Similar with BMW. 330 meant 3 liter engine. Now it’s all the “equivalent“ game.
- mrlonglong 6y agoMine's a 325i, that actually has a 3L engine.
- GoOnThenDoTell 6y ago230 deci-litre?
- deleted 6y ago[deleted]
- africanboy 6y ago230 centiliter
- analog31 6y agoSimilar story with audio amplifiers and "Watts." Also, I think that small gas engines like lawnmowers went through some kind of scandal related to their horsepower ratings.
- klodolph 6y agoYes, some amplifiers would be advertised with nonsense like “watts RMS”. The concept of “watts RMS” makes no goddamn sense.
- analog31 6y agoActually in the US, the term "Watts RMS" specifies that the measurement is done according to the FTC Amplifier Rule. Now that rule has its own pro's and con's of course, but at least it's pretty definite. With all of these things, there's a corresponding European rule as well. Whether the measurement method is appropriate to your use of an amplifier is of course anybody's guess.
- namibj 6y agoConsidering that the load impedance of audio amplifiers isn't always the same, it'd be a bad idea to measure output voltage in terms of gain compression points/clipping/max continuous. I agree the term "RMS" is kinda miss-appropriated, but it's short and tends to understood as something reasonably close to what it's actually about.
- amluto 6y agoHow about vacuum cleaners with HP? I guarantee that there isn’t a 3HP motor that works on a 120VAC (RMS) 15A (RMS) circuit.
- m-ee 6y agoA friend worked on a blender. The wattage number was derived from the inrush current when first turned on.
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- 11thEarlOfMar 6y agoI thought the 5nm referred to the smallest dimension in a FinFet device. Specifically, the fin: "In theory, the finFET hits its limit when the fin width reaches 5nm, which is close to where it is today." [0] https://semiengineering.com/5nm-vs-3nm/ https://semiengineering.com/5nm-vs-3nm/
- nyunai 6y agoInterestingly, there is one dimension that still tracks the node number fairly closely. In fact, the node number has never referred to transistor dimension, but the length of the gate electrode. A transistor would typically be about 4 times larger than that. The reason to refer to the length of the gate electrode is because that was always the smallest feature printed on the chip. And that is what defined the required resolution of the lithography process. So, a lithography process with a resolution of 32nm would be able to print chips with 32nm gate lengths. Much has changed, and now transistors are no longer planar, they are 3-dimensional fin structures (FinFETs). The gate length scaling has slowed down, and now is not the smallest feature on the chip anymore. The smallest feature in a modern FinFET process is actually the with of those 'fi s' that form the transistor channels. And as if by magic, they correspond pretty well to the node names, i.e. a 5nm process will have a fin width of about 5nm. You will likely not find that mentioned anywhere, it's just a fun fact that I noticed as a VLSI technologist.
- kayson 6y agoIt's still a little disingenuous because most performance parameters are directly related to transistor lengths, whether finfet or not. There used to be a concept of "scaling" where you could roughly estimate that going from a 40nm process to a 28nm process, for example, would save you (28/40)^2 percent power. Finfet disrupted that to some extent, but it partly held true as physical lengths actually continued to decrease with node names. By now, though, it is generally understood that state-of-the-art process node numbers doesn't mean much in that regard. I also just checked a handful of processes I have access to, and at least in these cases, the fin width doesn't scale with the technology name (e.g. 5nm and 7nm has 8nm fin width drawn in layout, and model indicates 27nm "width" per fin). This isn't much of a surprise to me, because foundries are just decreasing the number with newer generations of the tech, even if the lithography (the method by which features are etched into the silicon) hasn't significantly changed. For example, 3 generations of a single process were called 7***, then 5***, then 4***.
- dnautics 6y ago> It's still a little disingenuous because most performance parameters That's your bias. To a process engineer the parameter that matters is what wavelength you are blasting the mask with and what size a feature it can create.
- amelius 6y agoI can see how an average consumer would fall for "5nm". But this is targeted at engineers ...
- deleted 6y ago[deleted]
- fctorial 6y agoGHz would be a better analog of KWh. Anyone that isn't an electronics engineer is not qualified to talk about '?nm' technologies
- deleted 6y ago[deleted]
- cbozeman 6y ago> Anyone that isn't an electronics engineer is not qualified to talk about '?nm' technologies Jesus, this is the height of arrogance... Wendell Wilson isn't qualified to talk about this? Linus Sebastian isn't qualified to talk about this? Dr. Ian Cutress isn't qualified to talk about this? I would listen to all three of those before I listen to anything you say.
- blackrock 6y ago> Each transistor in a 5nm chip is actually between 28 and 36 nanometers in width. It's called 5nm because of a theoretical calculation based on transistor density So, TSMC is not really that far ahead after all? 28 nm is like a decade old now? This sounds like women’s vanity sizing. Size 6 is now Size 0.
- Waterluvian 6y agoThis is similar to all the disk space advertising and perpetual need to explain to friends why their disk isn't actually 500MB -> 2TB over the years.
- not2b 6y agoThe node size never referred to the actual size of the transistors. Back in the days when CMOS scaling was simple, it referred to the half-pitch, half of the center-to-center distance of the Metal 1 lines. The gate length was roughly the same, usually. But scaling had to be changed starting in roughly 2003 because atoms don't scale; the joke was that transistors were no longer switches, but just dimmers, because leakage was an increasing problem. Designs could no longer be simply scaled, producing a faster clock cycle for free; they had to be revised, and a FinFET looks very different from a traditional FET. To make further progress designs had to be changed, and things have gotten fuzzier. Processes from different foundries have different densities. Intel's process for a given node is denser than that of the big foundries like TSMC. See https://en.wikichip.org/wiki/technology_node https://en.wikichip.org/wiki/technology_node for more on this.
- m463 6y agoFunny, but Tesla actually stopped advertising battery sizes when the model 3 came out. It's actually a bit of work to find out (answer: 54 or 62 or 75 kWh)
- taneq 6y agoTrue, and this is precisely why they did it - this way they reap the benefit of any efficiency improvements. If their tech improves, it costs them less to build a "300 mile" car, rather than the buyer simply getting slightly more miles out of a 90kWh car.
- k__ 6y agoIf I look at HDD sizes and CPU "performance numbers", it doesn't surprise me that 5nm doesn't mean the actual transistor size.
- d58wfq7ps 6y agoWhy not it's what computer power supply have done for decades. 1500W PSU!!! But you'll never know how we came up with that figure!
- detaro 6y agoOutside of absolute no-name crap I haven't seen much of fake numbers on PSUs?