
Arm and TSMC Showcase 7nm Chiplet, Eight A72 at 4GHz on CoWoS Interposer - dmitrygr
https://www.anandtech.com/show/14914/arm-tsmc-demo-7nm-chiplet-system-w-8-cortexa724ghz-on-cowos-interposer
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phkahler
Did I miss it, or was there no mention of power consumption? We know they have
lower perf/mhz but if they're low enough power they might be decent per watt.

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loeg
It's not a product you'll ever be able to buy and AFAIK it's a press piece,
not something every released to 3rd parties for review:

> The chip will never be sold in volume, but it proves that technologies by
> the two companies can enable designers to build complex chiplet-based
> products with unique characteristics.

So it's kind of interesting from a "is it possible to take the AMD approach to
ARM cores" but it's not worth evaluating too hard because, again, you can't
buy it.

I think ARM hopes this inspires one of the less creative licensees (Qualcom?
Who else makes ARM besides Apple?) to pursue this as a product.

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reportingsjr
There are hundreds of companies that make or have made ARM cores, here are a
few off of the top of my head: Intel, Xilinx, STMicro, NXP, silicon labs,
broadcom, qualcomm, Samsung, Atmel (now microchip), etc etc.

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floatboth
Ampere (ex-APM), Marvell, Cavium (now also under Marvell), HiSilicon (Huawei),
Amazon (Annapurna Labs), Fujitsu…

Ampere, Cavium, HiSilicon, Fujitsu are the ones with actually custom cores.

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hinkley
Do chiplets give us more three-dimensional chips?

If the chips are stacked on top of a communications backplane it would seem
like that would be the case.

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wmf
Yes, chiplets stacked on a passive silicon interposer are often called 2.5D.
When you stack active dies it's called 3D integration.

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qaute
To elaborate:

A single IC die (a "chiplet" when stacked on others) is made of a layer of
transistors and wiring up to several hundred nanometers thick on top of a much
thicker (several hundred micrometer) silicon wafer substrate.

Yep, stacking these dies ("chiplets") on top of one another is one form of 3D,
and is definitely useful: IIRC, AMD's recent popular Ryzen 3000 line uses
chiplets, and the Raspberry Pi's RAM chip is stacked on top the CPU (in a much
cruder post-IC-manufacturing assembly process). The shorter distance between
dies (compared to placing them in separate plastic packages on a PCB) can lead
to maybe an order of magnitude improvement (in speed/power/etc). It's hard to
stack more than a few layers.

The most ambitious form of 3D design (and the one most people probably think
of) is multiple thin layers of transistors on a single die ("monolithic 3D");
this would give maybe another order of magnitude improvement. Monolithic 3D
memory chips are becoming popular (V-NAND, etc), with the most recent at ~100
layers. Monolithic 3D CPUs are still an unsolved problem because they need
different, more difficult process steps and better heatsinks (but we're
close!).

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floatboth
Is HBM also stacked in layers? IIUC there's like four layers of memory on each
HBM2 die

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Bayart
Yeah it's 3D-stacked. 4 layers for HBM, 4 for HBM and 12 for HBM2E.

It's neat but really expensive, and I don't think the gains for RAM in that
sort of designs are that big compared to computing cores outside of edge
cases.

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Bayart
Meant to say *8 for HBM2

