A note on Operating Systems

Cogsys is real time software; simply put, timing matters. This is why a real-time Linux kernel is used. The real-time kernel uses all the system resources it needs, and then surrenders control to non-real-time processes when it is idle. In Cogsys 4, there are two real-time processes: one to update the millisecond counters and vertical retrace flag, and another to gather keyboard inputs. These values are passed to the non-real-time part of Cogsys (the user interface) via a shared memory area and a fifo buffer. The user interface could not be put into the real-time kernel, because kernel modules are not designed to generate screen output (neither text nor graphics).