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Did anyone forget that core memory is woven ? With knitting, beads and everything ?

https://dl.acm.org/doi/10.1145/3173574.3174105

Admit it, deep down, our inner engeering child also wants to build a semiconductor clean room ;)

I only have raw RAM, pastured RAM is wrong.

I get my DRAM needs at the RAM ranch.

What a time to be alive.

I put myself in the print-it-yourself-at-home group.

You’re not sure if someone building a RAM clean room in a shed is appropriate for HackerNews, literally “news for nerds”? A dictionary purchase may be warranted

If you haven't seen this one, I highly recommend it:

Indistinguishable From Magic: Manufacturing Modern Computer Chips

https://www.youtube.com/watch?v=NGFhc8R_uO4&t=2070s

It's quite old but I think there is no modern version of it.

I've tried posting to HN a few times but it hasn't gained traction for some reason, but I find it absolutely mind blowing.

I think if it's interesting to you then it's worth posting, and letting the voting system do it's thing. I only rarely post because by the time I've seen something it's usually already been posted

Tbh this is exactly the sort of thing I'd come here to see

Recently I saw a post about Bonsai trees on the front page. Making your own RAM is 100% more relevant to HN than quite a few posts I see on the main page.

2027. Upgrade your LLM with home made RAM so you can afford to have it design your flying car

2027. Just-in-time built software and hardware.

You measure the charge (if it is there) before it is completely gone (if it were ever there). Capacitors always leak, these capacitors leak fast.

Measuring the charge also removes some of the charge -- fast, compared to the leak spead.

DRAM chips have a circuit that writes the value back -- charges the capacitor up if there's supposed to be a charge, drains it if there's not supposed to be a charge.

Refreshes and normal reads are the same, except that normal reads sends the value(s) to the output pin(s) on the chip.

He has "only" shown the basic grid of capacitors and transistors. The chip he shown has no circuit to measure charges or to write them back afterwards. This makes it easier to test the basic grip and the basic capcacitors.

Pretty sure the proper read out and write back circuit comes in the next video.

> I still don't really get transistors :P,

The important bits here are:

- any two conductive plates close together with an insulator between make a capacitor (1)

- when a capacitor is charged, the energy goes into the electric FIELD

- that's the FIELD of the field effect transistor

- if the field is strong enough, that causes conduction between source and drain (along the "channel")

- the insulator is nanometers thick, so current leaks across it; at that scale, you can detect individual electrons quantum teleporting straight through it.

(1) technically like gravity there is a capacitance between any two objects in the universe, but it's only significant when you have relatively wide and close conductors

A transistor effectively is an AND gate. If there is a charge on both the source and the gate, then charge can move to drain. So if you charge up the capacitor and you connect it to the source of another transistor then you can check whether it is still charged by putting a charge to the gate and see if there is charge on the drain.

And you are right, that charge on the drain can then be used both to drive some logic and to activate the recharging of the capacitor that was just discharged.

By the way I am being handwavy about "charge" moving about, if you really want to learn the electronics it is more correct to call it a voltage relative to some ground that the charge always moves towards.

In the "real" DRAM chip, there is a large array of very tiny capacitors, with the switches which allow to connect one row of the array at a time to the readout column wires.

The capacitance of the wires themselves is typically an order of magnitude greater than that of the storage capacitors. So when the memory is read, the wires are first precharged to some standard voltage. Then the desired row of storage capacitors is connected to the wires, and the charges from the storage capacitors spread onto the wires, changing their voltages very slightly. These voltage deviations from the standard value are amplified by the "sense amplifiers". The amplifiers are sort of like flip-flops. Once they start in a state which "tilts" slightly to "zero" or slightly to "one", they go all the way to the full magnitude zeros and ones. This not only amplifies the signal, but also automatically brings the voltages on the wires and the still connected to them capacitors to the full magnitude, thus "refreshing" the data. The row is disconnected, and the next read cycle can start for some other row.

In the video, an array of 4x5 capacitors and the associated with them switches was fabricated. The capacitors in the video are several hundred times larger (12400 fF) than typical capacitors in a 64 Kbit DRAM (about 50 fF). I assume this is done so that in the later episodes the author could implement the readout electronics outside of the chip.

https://en.wikipedia.org/wiki/Dynamic_random-access_memory#P...

It turns out they intentionally drain a bit of the storage capacitor, and amplify that weak signal. Some of that amplified charge is then fed back to storage.

Jokes aside, seeing as this person has created their own clean room in a shed, and is making RAM, what exactly is stopping any company from doing this themselves and breaking into the RAM business?

I'd pay less for RAM that wasn't "certified" in some official way, at least it works.

Chairman Trump will have a semiconductor furnace in every backyard.

Actually possible if you mount google drive and move your swap file there.

If they put a pricing page, I think there would be someone who would buy it, especially nowadays when with embedded llms there is a huge hunger for RAM (as well as CPU). :))

With memory prices what they are maybe there is a business opportunity for a return of SoftRAM 95

And are doing exceptional things (like building their own cleanroom in a shed)

Content creation was always about content. If you can make something special and engaging, audience will come.

Is it? Looks like this video is "locked" on Patreon requiring "this post and more exclusive work. Join for $10/month" yet got, as of now, 329 611 views ... so are they just making $3M/month or is it not really working?

They will preemptively rent all the sheds in the usa.

It is not really feasible to fabricate usable integrated circuits at home. There is a huge difference between a one off demonstration of a principle that "sort of works", and perfecting the process to the point that it produces finished parts that can be relied on.

This guy is not exactly a regular person. He is a pretty unique case of a talented semiconductor engineer who has a home lab for side hassles. It is not a low effort thing. He runs the equipment 24/7, scrubs all the surfaces in the lab daily to keep it clean.

Still, with the lab and all of the equipment already at hand, it cost him several weeks of work to produce this demonstration of transistors and capacitors, which kind of work, but are still long ways from a "completely complete" 20 bit DRAM chip.

Unfortunately it is simply too much work for one person to maintain a viable semiconductor fabrication process, even when it is done semi-professionally.

Makes me wonder if in the far future it will be ever possible to do something crazy like 7nm processes at home

There's another video on YouTube by the same guy detailing how he built his backyard clean room shed. I was kind of surprised at how easy it was - it's definitely a construction project that requires some specialized knowledge, but the fact that it's tractable at all for one person with a shed is pretty amazing to me.

The furnace is a low cost off-the-shelf Chinese product from Anhui Beq Equipment Technology Co.

Much more impressive are the modifications to the microscope, transforming it into an improvised lithography machine, and the home made plasma etching machine, cobbled together from surplus components.

Of course, the whole thing, starting from the clean room, is extremely impressive -- Intel started their business in a much simpler facility.

The graphs towards the end were discharge curves for a single transistor/capacitor cell out of only 16 present, if I understood correctly? So "enough cells to count as memory" and "addressing logic" are definitely future work (it looked like he wanted to characterize what the refresh cycle would have to look like before actually building more.) I was kind of surprised that the "use a microscope as a photolithography projector" approach worked at all, it will be interesting to see how that scales up...

Photolithography is way more practical, 3d printing principles are already used here in stepping of the mask.