 It was considered by them a buggy and inefficient piece of software, though not much different than many operating systems of the era.At the CDC Arden Hills, Minnesota laboratories (where they referred to SCOPE as "Sunnyvale's Collection Of Programming Errors") they had a competing operating system, MACE.This was the Mansfield And Cahlander Executive (from Greg Mansfield and Dave Cahlander, the authors of the system).