Related Clues:
- Old PC interface
- Operating system that doesn't do Windows?
- Operating system before Windows
- Scale starters and enders
- Permissible acts
- __ and don'ts
- Tijuana two
- Operating system designed by AT&T employees
- MS-____
- Spanish 'two'
- Advice of a sort
- Bell Labs invention
- Two, in Leon
- Partner of Don'ts
- Twice uno