Who are the historians of the computing? The requirement I used for deciding who qualifies (for this post), is that the person has written multiple papers on the subject over a period that is much longer than their PhD thesis (several people have written history of some aspect of computing PhDs and then gone on to research other areas).
Maarten Bullynck. An academic who is a historian of mathematics and has become interested in software; use HAL to find his papers, e.g., What is an Operating System? A historical investigation (1954–1964).
Martin Campbell-Kelly. An academic who has spent his research career investigating computing history, primarily with a software orientation. Has written extensively on a wide variety of software topics. His book “From Airline Reservations to Sonic the Hedgehog: A History of the Software Industry” is still on my pile of books waiting to be read (but other historian cite it extensively). His thesis: “Foundations of computer programming in Britain, 1945-55″, can be freely downloadable from the British Library; registration required.
James W. Cortada. Ex-IBM (1974-2012) and now working at the Charles Babbage Institute. Written extensively on the history of computing. More of a hardware than software orientation. Written lots of detail oriented books and must have pole position for most extensive collection of material to cite (his end notes are very extensive). His “Buy The Digital Flood: The Diffusion of Information Technology Across the U.S., Europe, and Asia” is likely to be the definitive work on the subject for some time to come. For me this book is spoiled by the author towing the company line in his analysis of the IBM antitrust trial; my analysis of the work Cortada cites reaches the opposite conclusion.
Nathan Ensmenger. An academic; more of a people person than hardware/software. His paper Letting the Computer Boys Take Over contains many interesting insights. His book The Computer Boys Take Over Computers, Programmers, and the Politics of Technical Expertise is a combination of topics that have been figured and back with references and topics still being figured out (I wish he would not cite Datamation, a trade mag back in the day, so often).
Michael S. Mahoney. An academic who is sadly no longer with us. A historian of mathematics before becoming involved with primarily software.
Jeffrey R. Yost. An academic. I have only read his book “Making IT Work: A history of the computer services industry”, which was really a collection of vignettes about people, companies and events; needs some analysis. Must try to track down some of his papers (which are not available via his web page :-(.
Who have I missed? This list is derived from papers/books I have encountered while working on a book, not an active search for historians. Suggestions welcome.