| Operating system | Developer | First release | License |
|---|---|---|---|
| BESYS | Bell Labs | — | — |
| GM-NAA I/O | General Motors Research Laboratories, North American Aviation | — | — |
| University of Michigan Executive System | University of Michigan | — | — |
| Operating system | Developer | First release | License |
|---|---|---|---|
| BESYS | Bell Labs | — | — |
| GM-NAA I/O | General Motors Research Laboratories, North American Aviation | — | — |
| University of Michigan Executive System | University of Michigan | — | — |