[计] multiprogramming operation system
duō dào chéng xù shè jì cāo zuō xì tǒng ㄉㄨㄛ ㄉㄠˋ ㄔㄥˊ ㄒㄩˋ ㄕㄜˋ ㄐㄧˋ ㄘㄠ ㄗㄨㄛ ㄒㄧˋ ㄊㄨㄥˇ