MVS - Closely Related Operating Systems

Closely Related Operating Systems

Japanese mainframe manufacturers Fujitsu and Hitachi both repeatedly and illegally obtained IBM's MVS source code and internal documentation in one of the 20th century's most famous cases of industrial espionage. Fujitsu relied heavily on IBM's code in its MSP mainframe operating system, and likewise Hitachi did the same for its VOS3 operating system. MSP and VOS3 were heavily marketed in Japan, where they still hold a substantial share of the mainframe installed base, but also to some degree in other countries, notably Australia. Even IBM's bugs and documentation misspellings were faithfully copied. IBM cooperated with the U.S. Federal Bureau of Investigation in a sting operation, reluctantly supplying Fujitsu and Hitachi with proprietary MVS and mainframe hardware technologies during the course of multi-year investigations culminating in the early 1980s—investigations which implicated senior company managers and even some Japanese government officials. Amdahl, however, was not involved in Fujitsu's theft of IBM's intellectual property. Any communications from Amdahl to Fujitsu were through "Amdahl Only Specifications" which were scrupulously cleansed of any IBM IP or any references to IBM's IP.

Subsequent to the investigations, IBM reached multi-million dollar settlements with both Fujitsu and Hitachi, collecting substantial fractions of both companies' profits for many years. Reliable reports indicate that the settlements exceeded US$ 500,000,000. The three companies have long since amicably agreed to many joint business ventures. For example, in 2002 IBM and Hitachi collaborated on developing the IBM z800 mainframe model.

Because of this historical copying, MSP and VOS3 are properly classified as "forks" of MVS, and many third party software vendors with MVS-compatible products were able to produce MSP- and VOS3-compatible versions with little or no modification.

When IBM introduced its 64-bit z/Architecture mainframes in the year 2000, IBM also introduced the 64-bit z/OS operating system, the direct successor to OS/390 and MVS. Fujitsu and Hitachi opted not to license IBM's z/Architecture for their quasi-MVS operating systems and hardware systems, and so MSP and VOS3, while still nominally supported by their vendors, maintain most of MVS's 1980s architectural limitations to the present day. Since z/OS still supports MVS-era applications and technologies—indeed, z/OS still contains most of MVS's code, albeit greatly enhanced and improved over decades of evolution—applications (and operational procedures) running on MSP and VOS3 can move to z/OS much more easily than to other operating systems.