From the webpage:
Alan Turing (1912-54) is best-known for helping decipher the code created by German Enigma machines in the Second World War, and for being one of the founders of computer science and artificial intelligence.
This archive contains many of Turing’s letters, talks, photographs and unpublished papers, as well as memoirs and obituaries written about him. It contains images of the original documents that are held in the Turing collection at King’s College, Cambridge. For more information about this digital archive and tips on using the site see About the archive.
I ran across this archive when I followed a reference to the original paper on Turing machines, http://www.turingarchive.org/viewer/?id=466&title=01a.
I will be returning to this original description in one or more posts on Turing machines and semantics.