Graphcore Bow IPU ☆

Graphcore's Bow IPU was the first production chip to use wafer-on-wafer 3D stacking (with TSMC), putting a power-delivery die under the compute die. The IPU's 1,472 cores and on-chip SRAM anticipated later designs, but the company missed the LLM wave commercially and was acquired by SoftBank in 2024 — its team now builds AI silicon inside the SoftBank/Arm orbit.