High Quality Content by WIKIPEDIA articles! Multiple Virtual Storage, more commonly called MVS, was the most commonly used operating system on the System/370 and System/390 IBM mainframe computers. It was developed by IBM, but is unrelated to IBM's other mainframe operating system, VM. First released in 1974, MVS had been renamed multiple times, first to MVS/XA (eXtended Architecture), next to MVS/ESA (Enterprise Systems Architecture), then to OS/390 (when UNIX System Services (USS) were added), and finally to z/OS (when 64-bit support was added with the zSeries models). Its core remains fundamentally the same operating system. By design, programs written for MVS can still run on z/OS without modification.