Interactive Application System
| Developer | Digital Equipment Corporation | 
|---|---|
| OS family | RSX-11 | 
| Working state | Discontinued | 
| Initial release | 1975 | 
| Latest release | 3.4 / May 1990 | 
| Available in | English | 
| Platforms | PDP-11 | 
| Influenced by | RSX-11D | 
| Default user interface | PDS or MCR Command-line interface | 
| License | Proprietary | 
Interactive Application System (IAS) was a DEC operating system for the PDP-11. It was a fork from RSX-11D.
The last major release, Version 3.0, began distribution late 1979; the final version, 3.4, came out May 1990.