Rung 04 / Memory & Compute Architecture

Hardware

The silicon rung of the inference stack, read memory-first.

3.35 TB/s

Memory bandwidth of one H100 SXM's 80 GB of HBM3 — the wall the arithmetic waits behind

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A memory module with copper heat spreaders, on paper.

In scope: the memory hierarchy and the memory wall, HBM and DRAM scaling, bandwidth and capacity limits, processing-in-memory, accelerator and NPU architecture, advanced packaging, and interconnect including optical interconnect and co-packaged optics. Memory is the binding constraint of this cycle. Out of scope: photonic compute (computing in light, as distinct from communicating in light) and quantum computing — frontier science with no near-term effect on what a token costs — and consumer buying advice, which is an editorial beat rather than research.

An HBM die stack cut away at the corner, copper through-silicon vias exposed in section.
Memory wallHBMDRAMNPUsPackaging
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Sources compiled for this topic
TypeSourcePublished
PAPERMemory Scarcity, Open Models, and the Restructuring of the AI Industry, 2026-2030
Satoshi Matsuoka · RIKEN Center for Computational Science (R-CCS)

Quantitative scenario model showing the 2026 DRAM/HBM price surge creates a persistent entrant-incumbent inference-cost gap that never closes over 2026-2030 (3.2x in 2026, narrowing to ~1.9x in 2027, re-widening to 3-4x by 2029-30) via a depreciation-conveyor mechanism; five probability-weighted scenarios (Rotating Landlord Oligopoly 25%, Commoditization Crash 25%, Jevons Absorption 20%, System-Layer Re-differentiation 18%, Geopolitical Bifurcation 12%) map the resolution.

2026-07-08
Hardware — Memory & Compute Architecture | Knowledge Base | MenFem