Confidential. Progress report on the Automatic Computing Engine. WITH: Report on the pilot model of the Automatic Computing Engine. Part II. The logical design of the pilot model

Wilkinson, James Hardy. (1) Confidential. Progress report on the Automatic Computing Engine. Mimeograph typescript. [1], 127ff. 12 plates. N.p.: National Physical Laboratory, April 1948. 324 x 202 mm. Original tan printed wrappers, green cloth spine, small tear in upper portion of backstrip, corners a bit worn, back wrapper a bit creased. The word "Confidential" crossed out on both front wrapper and title, "Not for publication" and illegible initials inscribed on front wrapper. (2) Report on the pilot model of the Automatic Computing Engine. Part II. The logical design of the pilot model. Mimeograph typescript. [4], 18pp. 6 diagrams (stapled together) in pocket of back wrapper. N.p.: National Physical Laboratory, September 1951. 331 x 203 mm. Original printed wrappers, cloth backstrip. Very good. Ownership stamp of W. W. Youden on front wrapper. Together two items. Bookplate of Erwin Tomash in each part.

First Editions of Both Parts, and Extremely Rare, with OCLC recording only 6 copies of Part 1 and one of part 2. The National Physical Laboratory's ACE (Automatic Computing Engine) was designed by Alan Turing, who began working on the project a few months before he joined the NPL's mathematics division on October 1, 1945. Construction of the ACE began with a "test assembly" to try out Turing's ideas of computer design; after Turing's departure from the NPL in September 1947, the project was taken over by his assistants, James H. Wilkinson and Michael Woodger. Wilkinson's 1948 report (no. [1]) is one of the earliest documents on the ACE and contains probably the most detailed description of the work done to date in building the test assembly. The numerous programs published in this report include some of the earliest surviving examples of Turing's programming for the machine.

In 1949 the NPL issued a second report on the ACE written by Stanley Gill, titled Automatic Computing Engine: Progress Report No. 2, Description of Hollerith Input and Output for the Pilot Model (not included here). In the same year the original ACE test assembly was abandoned and a redesigned simpler version began construction; this simplified version, described in Wilkinson's 1951 report (no. [2]), came to be known as the Pilot ACE. Wilkinson's introduction to the 1951 report noted this change in the design process:

"In an earlier Progress Report [i.e., no. (1) above] the logical designs of two machines were described, the first a small machine referred to as a Pilot model, the second a large scale machine referred to as the Automatic Comput ing Engine (A.C.E.). The machine which is the subject of this [1951] report is roughly equivalent to the pilot model described in [the 1948 report], but it differs sufficiently in detail to make it more convenient to give a self-contained description of its logical design rather than summarise its points of difference (p. 1)."

The 1951 report is subtitled "Part II" but we have found no evidence of a "Part I," and it seems clear from Wilkinson's introduction that the 1951 report was meant to serve as the second part of the 1948 report. OCLC records only one copy of the 1951 report, at the University of Illinois; the catalogue description incorrectly gives the pagination as 127 leaves, perhaps confusing it with the 1948 report.

Despite its prototype status the Pilot ACE was immediately pressed into service on its completion, as it was then the only computer in a British government department. It remained in operation until 1956. Origins of Cyberspace 933. Yates, Turing's Legacy: A History of Computing at the National Physical Laboratory 1945-1995, 337, no. 138. Origins of Cyberspace 933. Yates, Turing's Legacy: A History of Computing at the National Physical Laboratory 1945-1995, 337, no. 138.