Convergent Technologies Operating System
| A Burroughs B25 computer running CTOS | |
| Developer | Convergent Technologies | 
|---|---|
| Written in | PL/M | 
| Working state | Discontinued | 
| Initial release | 1980 | 
| Platforms | x86 | 
| Kernel type | Microkernel | 
| License | Proprietary | 
The Convergent Technologies Operating System, also known variously as CTOS, BTOS and STARSYS, is a discontinued modular, message-passing, multiprocess-based operating system.