DOS Operating System

• REAL-32
• RxDOS

• Computers: Software: Operating Systems: x86: DOS 

• On Time Informatik GmbH  - Features a powerful real-time multitasking system that was designed for software creators who wish to implement professional process control applications on PCs using DOS or other embedded systems.
• S and H Computer Systems, Inc.  - Serves as an alternative to both the Unix and Microsoft operating systems.