| Year | Versions | Comment |
|---|---|---|
| 1967 | 1? | PDP-6 |
| 1968 | 350-444 | |
| 1969 | 530 | KA10 support? |
| 1970 | Virtual memory | |
| 1971 | 672-703 | Arpanet support |
| 1972 | 720-724 | |
| 1973 | 785-850 | |
| 1974 | 915 | KL10 support |
| 1975 | 994-998 | |
| 1976 | 1025-1044 | |
| 1977 | 1066-1097 | |
| 1978 | 1099-1136 | PDP-6 support dropped |
| 1979 | 1138-1168 | |
| 1980 | 1173-1196 | |
| 1981 | 1198-1256 | |
| 1982 | 1256-1283 | |
| 1983 | 1312-1360 | |
| 1984 | 1361-1486 | |
| 1985 | 1487-1539 | KS10 support |
| 1986 | 1554-1588 | |
| 1987 | 1591-1616 | |
| 1988 | 1618-1632 | |
| 1989 | 1633-1634 | |
| 1990 | 1640-1644 | Last MIT version |
| 1992 | 1645 | By Ken Harrenstien |
| 1997 | 1647 | |
| 2002 | 1648 | By Paul Svensson |
| 2005 | 1649 | By Björn Victor |
| 2007 | 1650 |