Despite diehard adherence among large users to 370 architecture, and the claims made by IBM for Systems Applications Architecture, the operating system world is undergoing a quiet upheaval: according to International Data Corp forecasts published in Computerwoche, the 6% share of the market taken by Unix in 1986 will soar to 22% by 1991; IDC sees 370 operating systems dropping to 24% from 26%, IBM Systems 36 and 38 dropping to 2% from 4%, and DEC’s VMS climbing just 1% to 6% in the same period; overall, IDC reckons the operating software market will be worth $120m in 1991 compared with $87m in 1986.