Extremely rare first edition book by Alan Turing: Programmers' Handbook for Manchester Electronic Computer Mark II, with errata sheets dated March 13 and March 25, 1951. Softcover, 8 x 13, stamped on the front cover, "With the compliments," and annotated in an unknown hand in ink, "of A. M Turing." Compiled by Turing, the handbook instructs users on the programming of what he called the Manchester Electronic Computer Mark II (typically referred to by others as the Ferranti Mark 1). Notably, the handbook contains instructions for the 'hooter,' which provided auditory feedback to the operator via loudspeaker, producing "a steady note, rich in harmonies." This function would be exploited by Turing's friend Christopher Strachey to produce the earliest known recording of computer-generated music in late 1951. In fine condition, with some annotations and corrections throughout.