Answering the question: the handwritten note is indeed by Chuck Baker (see https://news.ycombinator.com/item?id=12569853 https://news.ycombinator.com/item?id=12

Answering the question: the handwritten note is indeed by Chuck Baker (see https://news.ycombinator.com/item?id=12569853 https://news.ycombinator.com/item?id=12569853) — matches the handwriting at https://archive.computerhistory.org/resources/text/Knuth_Don_X4100/PDF_index/k-9-pdf/k-9-u2769-1-Baker-letter.pdf https://archive.computerhistory.org/resources/text/Knuth_Don... It's interesting that the editor didn't know the author of one of the articles in their magazine!