Google TPU v1–v3 ☆

TPU v1 (deployed 2015, revealed 2016) was a 28 nm inference ASIC built in 15 months after Google calculated that voice search at scale would otherwise require doubling its data centers. v2 (2017) added training, HBM and the first pods; v3 (2018) went liquid-cooled at 1,024-chip scale and trained early BERT-era models. Together they proved a hyperscaler could out-build the merchant market for its own workloads — the argument every custom AI chip since has followed. AlphaGo ran on TPUs when it beat Lee Sedol in 2016.