Comment IBM's First OS still supported: DOS/VS release 34 (Score 3, Informative) 245
IBM's First OS for the 16k IBM 360 model 30 in 1964 was DOS. DOS evolved to DOS/VS release 34 by 1968.
DOS/VS release 34 is still supported and runs on
several hundred systems. The LAST bug in DOS/VS r34
was fixed in 1980.
