High Quality Content by WIKIPEDIA articles! Multiprogramming with a Variable number of Tasks (MVT) was the most sophisticated of three available configurations of the OS/360's control program. In turn, OS/360 was an operating system for the IBM System/360 line of computers. MVT was intended for the largest machines in the System/360 family, introduced in 1964, but it did not become available until 1967. Early versions had many problems and the simpler MFT continued to be used for many years.