Ackren · Three folds · 16 MB XIP
Octavo, three folds
Sixteen megabytes, executed in place, no card at all, and a weaker guarantee said with the name.
The floor
Sixteen megabytes and nothing else
Octavo runs from execute-in-place flash with no card, no PSRAM and no filesystem. It is the format for a device that was never going to have storage: a handset accessory, an instrument panel, a hearing device.
Everything else in the system is unchanged. The engine is the same engine, the packs are the same packs, and the derivation log is written to the same schema.
The guarantee
Weaker, not smaller
Sixteen megabytes leaves room for twelve-bit fingerprints, which puts the silent false accept rate at one in 4,096. Quarto is one in 16.7 million. That is four orders of magnitude and it is a different guarantee, not a smaller build.
This is the single most important sentence on this page: Octavo carries a weaker guarantee rather than merely less content. We state it in the same breath as the name, every time, including in sales conversations, because a limit disclosed in a footnote reads as a limit that was found rather than one that was known.
Do the arithmetic first
At a billion lookups the expected number of silent false accepts is roughly 6,100. If your deployment approaches that volume, or if a silent wrong answer is a safety event rather than an annoyance, size for Quarto.