From: Paul Kranenburg <pk@cs.few.eur.nl>

   It seems to me that the unconditional FIFO flush at the top of
   ncr53c9x_select() can also participate in the race. Like the insertion
   of command bytes, it can happen just after a target has succesfully
   acquired the bus and one or both of the selection and message IDs
   are already in the FIFO.

   [...]

   Anyway, can you try commenting out the NCRCMD_FLUSH command at
   line 420 for a moment and see if that makes a difference?

Ok, done: the result is that I get

esp): illegal command: 0x1 (state 4, phase 7, prevphase 7)

fairly quickly on reading or writing (sometimes, prevphase is 3)

Joachim