That's really neat. TIL.

So the way this works seems to be this: It's an SRAM and an EEPROM in one little package along with a controller that talks with each, with a little capacitor (this clock uses 4.7uf) placed nearby.

The SRAM part does all of the normal SRAM stuff: It doesn't wear out from reading/writing, and as long as it has power it retains the data it holds.

The EEPROM does all the normal EEPROM stuff: It stores data forever (on the timescale of an individual human, anyway), but has somewhat-limited write cycles.

The controller: When it detects a low voltage, it goes "oh shit!" and immediately dumps the contents of the SRAM into EEPROM. This saves on EEPROM write cycles: If there are no power events, the EEPROM is never written at all.

Meanwhile, the capacitor: It provides the power for the chip to perform this EEPROM write when an "oh shit!" event occurs.

When power comes back, the EEPROM's data is copied back to SRAM.

---

Downsides? This 47L04 only holds 4 kilobits. Upsides? For hobbyist projects and limited production runs, spending $1 to solve a problem is ~nothing. :)

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bonsai_spool 5 hours ago | parent [-]

[flagged]

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Dachande663 4 hours ago | parent | next [-]

Upvoted because this stinks to high hell of an LLM response. Half the GPs comments seem to be in a similar vein. It’s such a shame but you can’t fight the trolls so don’t take it to heart.

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ssl-3 5 hours ago | parent | prev [-]

"Hey, someone on the Internet used decent diction! Obviously, this means I must accuse them of being a bot!"

(Hey Dang. Can we get a ban button? There's a few people here that are impossible to conduct rational discourse with. My sanity would improve if they were simply gone from my view.)

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bonsai_spool 3 hours ago | parent | next [-]

You've edited the response since you posted it. I think there's a difference between diction and the standard output of ChatGPT et al.

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rfl890 12 minutes ago | parent | next [-]

I have trouble believing that you're pointing this out in good faith.

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ssl-3 3 hours ago | parent | prev [-]

I'd like to say that I'm sorry that you feel that way, but frankly: My ability to feel anything empathetic about you dwindles by the moment.

Please stop fucking with people in this way. It's callous, unnecessary, and antithetical to the greater good. We don't come here to get accused of things.

(edit: Today, I learned about the existence of a chip that does a clever thing. That made me curious: After all, I've been passively wondering for -decades- about how electronic things remember their previous state without power, and without hammering an EEPROM.

I could have learned more about this at any time over the years, but I just never bothered with doing so.

And today, it was right in front of my face -- with a part number! That gave me a very easy place to start, so I started.

I read up on it a bit using the datasheet and a whitepaper. I learned some about how it does that clever thing, and I wrote a few sentences about this new-to-me stuff in a way that I felt would be approachable and appreciated by this particular audience.

That's what we're here for -- to be curious, to share ideas, and to learn stuff from others. Not for fucking with people.)

	▲	antx an hour ago \| parent [-]
		And we're also here to use double dashes, aren't we.

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ninalanyon 5 hours ago | parent | prev [-]

You could create a browser user script to do it locally.

	▲	ssl-3 4 hours ago \| parent [-]
		That's not a terrible idea. An extra UI element or two should be enough. Maybe with sticky options for collapse-by-default or hide-by-default at the top of each HN comment section. And the list of usernames can be stored and edited in the purveyor's HN bio (in plain text, like a monster), so that it works automatically across devices.