When all tasks are waiting on i/o or for time to pass, TIdle()
uses select() to wait for something to happen and then wakes up
the highest priority task that becomes ready to run.
Source: ../mlexec.c.html#TIdle
char * TMain( char *cmd, int pri_ret )
TMain parses commands submitted through stdin, after initially
running the command script "ml.rc".
Source: ../mlexec.c.html#TMain
char * TPrintf( char *cmd, int pri_ret )
Since serveral thousand bytes of stack space must be allocated for
the occasional sprintf(), the task TPrintf() is set up to do
all output formatting on behalf of any other task.
Source: ../mlexec.c.html#TPrintf