The smallest and first model from CyanoAI — a 190.5M-parameter dense English base LM. Named after Prochlorococcus, the tiniest and most oxygen-producing photosynthetic organism on Earth: small, dense, and outproducing everything its size. All variants share the same architecture, tokenizer, and vocabulary, so they are drop-in interchangeable. Training corpus: a curated ~826GB English mixture (web / books / code / reference), stream-packed with the tokenizer jointly shipped in this repo. This is a base model — it speaks fluent Wikipedia-style prose but has not been aligned. For chat or assistant behaviour, start from the SFT or aligned variants. Zero-shot on wikitext (JSON subset, ~500k…
Open weights
apache-2.0
190M parameters
4,096 tokens
Supervised fine-tuned version of Prochlo-190M-Base — a 190.5M-parameter dense English SLM trained from scratch. All variants share architecture, tokenizer, and vocabulary. 26-item behavioral rubric (format adherence, anti-sycophancy, code, concision): 61.5% pass. Strong on code instructions and factual QA. Weak on concise replies, long multi-turn coherence, and arithmetic. English only — Chinese input produces garbage by design. The chat format is plain text with control tokens, not a chat template: Note: weights are sharded across 32 safetensors files with a model.safetensors.index.json; frompretrained handles this transparently. Apache-2.0
Open weights
apache-2.0
190M parameters
4,096 tokens
