Reminiscences of Project Y and the ACS Project

These reminiscences relate to the period that Brian Randell spent between 1964 and 1966 first at IBM Research working on Project Y and then in the IBM Systems Development Division on the resulting ACS Project--then-secret projects that aimed to build a supercomputer that would be 100 times faster than Stretch. Randell\´s account is based in part on his memory, but also makes extensive use of the small set of files that he had retained, mainly relating to patent applications. A scanned copy of one of these files, the paper "Dynamic Instruction Scheduling," that he coauthored with Lynn Conway, Don Rozenberg, and Don Senzig in February 1966, is available as an online Web extra https://s3.amazonaws.com/ieeecs.cdn.csdl.public/mags/an/2015/03/man2015030055s.pdf and in Newcastle University\´s online archive at www.cs.ncl.ac.uk/publications/trs/papers/891.pdf. Because of space constraints just the initial three pages of this paper are included in the present article, which also includes the text from a section on "Interrupts" that was added to the 1969 IBM San Jose Technical Report version of the 1966 paper.