Por que o sono ininterrupto é indicado por 'D'?

Question

De "man ps":

R = Running or Runnable
S = interruptable Sleep
T = sTopped
Z = Zombie

D = uninterruptible sleep (usually IO)

De onde vem este D?

    

Answer 1

Da página de manual do 4BSD ps :

The state is given by a sequence of four letters, e.g. ''RWNA''. The first letter indicates the runnability of the process: R for runnable processes, T for stopped processes, P for processes in page wait, D for those in disk (or other short term) waits, S for those sleeping for less than about 20 seconds, and I for idle (sleeping longer than about 20 seconds) processes.