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Show HN: Running PrismML's Bonsai inside DRAM by breaking DDR4 timing rules
23 points by pcdeni 11 days ago | hide | past | favorite | 10 comments
The excitement surrounding PrismML’s 1-bit/ternary Bonsai models has the industry closely watching how smartphone giants, particularly Apple, will implement LLMs on edge devices.

Moving AI on-device is a brilliant and necessary strategy. It ensures absolute user privacy in alignment with EU regulations, fundamentally shifts the economics away from costly cloud inference, and paves the way for a significant hardware upgrade supercycle as users seek true AI-capable silicon.

To create a smart on-device "Semantic Router," models need to reach the 27B+ parameter scale. Achieving this on a phone requires extreme quantization, such as PrismML’s ternary weights.

However, a critical hardware reality often overlooked by the software world is that fitting the weights in RAM is not equivalent to moving them. Running a 27B ternary model on standard LPDDR encounters a significant memory bandwidth limitation. Transferring gigabytes of data across the SoC bus for each token generation can lead to thermal throttling of the NPU and excessive battery drain.

This raises an important question: why are we still transferring data to the compute? Why not execute AI inference natively within the memory?

Frustrated with academic PIM simulations that overlook bare-metal physics, I developed CaSA, an architecture that performs ternary LLM inference directly inside COTS DRAM through charge-sharing, completely bypassing the memory bus.

Software quantization is a great initial step, and CaSA provides the physical hardware substrate needed to complete the bridge: https://github.com/pcdeni/CaSA

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Jebus, that is some sloppy prose. Can people not even be bothered to write the summary themselves, anymore? AI doesn't want anything, so they can never have a point of view, so their prose rambles incoherently across all the various prompts they've seen in a project. This project sounds like the ramblings of a crazy person. Even though the fact that DRAM can do any computation is interesting, nobody should have to read this mess.

"why are we still transferring data to the compute? Why not execute AI inference natively within the memory?"

You already answered that question: 47.5 seconds per token from a tiny 2B 1-bit model model.


Very interesting. I don't see it mentioned so I'll ask:

Would being able to alter voltage levels on the fly (eg, cells x y and z get 1.25 while abc get 1.2) expand the ability here?


This is a first, may I ask where it comes from? You might have a line of thought but I cannot tell from here. I am using off the shelf memory, adjusting the voltage didn't come up.

AI is helpful to understand the world around us. And also to do the posting while I focus on the doing. Although some of these comments don't require much while perplexingly complain about slop... Are you maybe using it wrong?

Very interesting. Do you have any descriptions or writeups written by a human?

yes, trust me, it does not get any more simple.

You are saying this is 13 times faster? More proof please. How do we set it up? I really want this to be a real thing.

It's not a real thing. It's AI psychosis based on a real thing that is interesting but not very useful, thus far (the real thing it is based on: https://arxiv.org/abs/2503.23817)

it is not faster compared to a GPU. The prototype works end to end with off the shelf memory, to make it "real" silicon level changes would be needed for the memory.

Interesting project, but the slop readme made me quit reading halfway



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