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Analog computing may be coming back

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Re: Analog computing may be coming back

#21

Post by nextaccountic »

noduerme wrote: post #19
chongli wrote: post #17

Earlier quoted context omitted.

You can do math with analog circuits. This was the original purpose of the opamp (operational amplifier) [1]. [1] https://en.wikipedia.org/wiki/Operational_amplifier

huh. So the distinction between analog and digital has nothing to do with whether the logic itself is binary, just whether the delivery of signal to gate is absolute or ranged? Something has to gate the signal, right? I always thought "analog" referred to processes that didn't reduce things to a binary at some step along the way...(?)

opamps aren't binary

Re: Analog computing may be coming back

#22

Post by zozbot234 »

Analog computing sucks. It's inherently sensitive to noise and random variation in your devices that's basically ubiquitous with modern chip-making processes. Digital electronics actively reject noise at every step in a computation, albeit at the cost of wasting energy in the process. With analog, a more complex computation becomes exponentially harder.

Re: Analog computing may be coming back

#23

Post by chongli »

noduerme wrote: post #19
chongli wrote: post #17

Earlier quoted context omitted.

You can do math with analog circuits. This was the original purpose of the opamp (operational amplifier) [1]. [1] https://en.wikipedia.org/wiki/Operational_amplifier

huh. So the distinction between analog and digital has nothing to do with whether the logic itself is binary, just whether the delivery of signal to gate is absolute or ranged? Something has to gate the signal, right? I always thought "analog" referred to processes that didn't reduce things to a binary at some step along the way...(?)

As far as the circuits are concerned, there’s no such thing as digital. For human engineers, digital is a convention. Well, technically, there are numerous digital logic conventions based on different voltage standards.

For example, you might decide that 0 volts is a logical 0 and 5 volts is a logical 1. If you get everyone to agree to this convention then you can build components that talk to each other. Unfortunately, it’s very difficult (impossible) to get to exactly 0 or exactly 5 volts. So instead you decide that anything less than 2 volts is a logical 0 and anything greater than 3 volts is a logical 1. This setup makes your circuits quite robust to noise.

To further improve things, you might decide that when you want to output a logical 0 you must produce a voltage less than 1 volt and if you want to output a logical 1 you must produce a voltage above 4 volts. This convention allows your system to continually correct voltages away from the undefined region (between 2 and 3 volts). A marginal input of 3.1 volts gets interpreted as a logical 1 and then output above 4 volts. This “self-correction” is what made digital computers the revolution they are.

Re: Analog computing may be coming back

#24

Post by shrubble »

I think that the author is wrong.

Analog computer's weak point is the power supply, such that many companies making them ended up having to manufacture their own to very high standards, such as big capacitors with 0.1% tolerance. Reason is that you are using the analog voltage and thus poor power regulation leads to inaccurate results.

With newer analog computer setups more is integrated into the chip itself, making power supply issues much less of a problem.

Re: Analog computing may be coming back

#25

Post by [deleted] »

choudharism wrote: post #2

The mark of a maturing domain is the evolution from only general tools to general + specialized. We've gone from only CPUs to CPU + GPU to specialized AI chips (Neural Engine, Tensor chips etc.) and specialized computing is a big tent which can fit many different architectures together. Analog computing is the closest thing to bioengineering in fundamental computer science that I know of, so I am confident that it wi…

[deleted]

Re: Analog computing may be coming back

#26

Post by silvestrov »

zozbot234 wrote: post #22

Analog computing sucks. It's inherently sensitive to noise and random variation in your devices that's basically ubiquitous with modern chip-making processes. Digital electronics actively reject noise at every step in a computation, albeit at the cost of wasting energy in the process. With analog, a more complex computation becomes exponentially harder.

Analog computers are like LP records: only good for nostalgia.

Re: Analog computing may be coming back

#27

Post by noduerme »

chongli wrote: post #23
noduerme wrote: post #19

Earlier quoted context omitted.

huh. So the distinction between analog and digital has nothing to do with whether the logic itself is binary, just whether the delivery of signal to gate is absolute or ranged? Something has to gate the signal, right? I always thought "analog" referred to processes that didn't reduce things to a binary at some step along the way...(?)

As far as the circuits are concerned, there’s no such thing as digital. For human engineers, digital is a convention. Well, technically, there are numerous digital logic conventions based on different voltage standards. For example, you might decide that 0 volts is a logical 0 and 5 volts is a logical 1. If you get everyone to agree to this convention then you can build components that talk to each other. Unfortunate…

so .. the only thing I could imagine making a system "analog" would be if each voltage were treated differently, rather than segregated into 0 or 1 as you just described. If a whole range of signal between 0 and 5 volts were directly output to something like a speaker system, that would be analog. I guess I'm wondering how this optical computer would get around the bottleneck of reducing everything to binary as you described with an electrical system.

Re: Analog computing may be coming back

#28

Post by pjc50 »

staunton wrote: post #15
orbifold wrote: post #3

One of the things that I fully not expect to be successful is optical computing. There are just a lot of academic groups that are doing optics and they like to invent new reasons why whatever they are up to is relevant. For physics reasons the integration density of optical compute elements is abysmal and will remain so forever . Other technologies like spintronics at least have the chance to work sometime in the fut…

> For physics reasons the integration density of optical compute elements is abysmal and will remain so forever. Could you give some details? Claims about "forever" often don't hold up. I guess you're referring to things like component size in relation to the wavelength of light used? One could use smaller wavelengths. Integrated photonics is certainly being done and also commercially relevant (in telecommunications)…

> I guess you're referring to things like component size in relation to the wavelength of light used? One could use smaller wavelengths

The same issues that affect electronic VLSI manufacturing also apply to trying to use light on-chip. The semiconductor industry had to transition to EUV (13.5nm) light to make it work. But that has huge and inefficient light sources.

Photonics makes sense if one end of your system has light on it; if you're building a LIDAR system, or data transmission over fiber, or somesuch. I have not yet seen anyone doing computation at scale in light.

Re: Analog computing may be coming back

#29

Post by nanna »

silvestrov wrote: post #26
zozbot234 wrote: post #22

Analog computing sucks. It's inherently sensitive to noise and random variation in your devices that's basically ubiquitous with modern chip-making processes. Digital electronics actively reject noise at every step in a computation, albeit at the cost of wasting energy in the process. With analog, a more complex computation becomes exponentially harder.

Analog computers are like LP records: only good for nostalgia.

Depth of sound, long term storage, ease of navigation, there are lots of reasons people prefer vinyl that aren't based in nostalgia.
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