Trademark A multiaccess operating system designed in project MAC to provide a MULTiplexed Information and Computing Service. The MULTICS system made extensive use of ‘rings’ of hardware protection of access to memory in order to achieve management of a very large virtual memory. Users operating on files move their entire file into memory in order to operate on it. The MULTICS system was implemented on specially commissioned hardware constructed by General Electric, and the entire project was later taken over by Honeywell Computer Systems.