Chuck Baker [0], according to the index [1], which also has a link to the cover letter [2] from when he sent this and some other papers to Knuth.

[0] http://history.computer.org/pioneers/baker.html

[1] http://archive.computerhistory.org/resources/text/Knuth_Don_...

[2] http://archive.computerhistory.org/resources/text/Knuth_Don_...