[en] Although it had been designed as a 600 MeV proton accelerator, the CERN synchrocyclotron was modified at the end of the 1970's to be able to accelerate ions up to mass 20. A programme of physics at ∼ 100 MeV/N developed rapidly, at a time when most of today's custom-built heavy ion accelerators for more than 20 MeV/N were under construction or still on the drawing board. The intention was to enable physicists to perform some immediate experiments and then later to phase out this mode of operation as other machines came on-line. Thus the SC's ion programme was brought to a close at the beginning of 1986. (author)