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Comment by sverige | Hacker News Reader

Speaking of things I wish were real, whatever happened to the DNA-based computer I was promised 30 years ago? Or the memristors that would allow instantly booting back to the state my computer was in when I turned it off last night?

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DNA computers? I think the answer is “we outclassed them”. At 10nm, transistors are about the size of 10 base-pairs at this point, but much faster and much less error prone.

I think DNA has semiconductors beat on average information density though. A tube of DNA can contain a datacenter’s worth of information. Read times are abysmal and error rate is through the roof, but it’s relatively stable on the order of hundreds of years.

>stable on the order of hundreds of years

Just isn’t something in super high demand. That and density are probably the only major advantages right? And I don’t imagine the equipment to "read" that data will be very compact in the foreseeable future.

If the demand was high enough I bet there would already be profitable companies pursuing it. I do see it as a potential market though. It’s no fun having a cold storage archive that needs constant hardware replacements.

I would imagine reading would be done in a similar way as it is today: amplification and sequencing. Data would have to be given a hefty amount of data correction. There are no apparent show stoppers that I’m aware of, just not enough interest.

error rate is actually pretty low compared to HDD I believe

We're still not even close for energy efficiency though. I can't remember the exact figures, but for most tasks the Brain is much more efficient per joule than any CPU.

This is true for things people have evolved to do, but a cell phone can do a lifetimes worth of arithmetic in less than a second using negligible energy relative 2000 calories per day for 70 years

True, though I don’t think that’s a “DNA” computer in the same way that merely using semiconductors doesn’t makes my laptop a “quantum” computer.

Going with the Kuzweil estimate on Wikipedia, human brains are about 1e15 ops/Joule, whereas the best in the Green500 list (June 2019) is 1.76e10 ops/Joule.

> Or the memristors that would allow instantly booting back to the state my computer was in when I turned it off last night?

I would agree with you, but with the current ability to suspend, I don't see the point. I always just suspend when I would otherwise power-off. The only times I power-off now are when I don't use my laptop for many days and the battery just completely drains itself, when I want to load an updated kernel, or when the power goes out in the neighborhood. They're all pretty rare events.

If you're talking about using DNA to solve NP hard problems the reason is that it just kicked the problem to DNA quantity. While the computation was theoretically constant time, the DNA required would be exponential. If you make it suboptimal then may as well using an Ising computer.

If you're talking about DNA storage, then cost, durability, speed, energy, reliability, size, etc. Are all issues.

Oh and memristors have too little endurance, are too slow and consume too much power. Like, we're talking 10^5 worse than DRAM.

What might work is NRAM or correlated electron RAM.

Isn't Intel XPoint/Optane is that? RAM-like speeds with persistence.

I think, and don't quote me here, Optane is still an order of magnitude away from RAM in terms of IOPS (read latency). It's massively better than traditional SSDs, but RAM is still waaayyyyy better. So, Optane could be useful as boot drive and fast-ish swap space, but that's probably it. In most applications Optane won't feel that different from your usual nvme discs. I think. I can't afford one, haha

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