AMB stands for "Ancient Machine Book". It is an extremely lightweight
file format meant to store any kind of hypertext documentation that may
be comfortably viewed even on the most ancient PCs: technical manuals,
books, etc. Think of it as a retro equivalent of a *.CHM help file.

This web page holds the format specification, as well as reference
tools to work with the format: AMB (the reader) and AMBPACK (archive
packer/unpacker). All tools are published under the terms of the MIT
license.

*mirrored from https://ambook.sourceforge.net/