IO-submodules such as the MIDAS products seem suitable to collect, buffer and redistribute the high data output from COMPASS. The data organization, flow and memory management is provided by the i960 onboard processors. Such processors, however, do not support OS-9 and Lynx as they have no memory management unit. They would most likely be used without operating system exclusively running programs cross-compiled and downloaded from a standard workstation. Furthermore such an I/O-processor, although ideal for the data flow management, would probably be inappropriate for the control/monitor schemes required.
In such a scenario, Lynx running on a PPC platform would provide a (pretty-nearly) real-time operating system with efficient POSIX features and a comfortable (nearly) UNIX environment. OS-9's real-time performance is likely better, but such a machine, being more loosely coupled to the hardware than today's event-builders, would suffer less than would have those earlier systems from such weaknesses and benefit more from the obvious advantages of UNIX-type-compatibility.
The choice of the real-time operating system is however not regarded as crucial to the design of the DAQ of COMPASS.