ANOTHER BIT IN INQUIRY DATA

GFRAZIER at ausvm6.vnet.ibm.com GFRAZIER at ausvm6.vnet.ibm.com
Thu Aug 25 07:11:45 PDT 1994


John Lohmeyer asked:

   Should we add a bit to the INQUIRY Data to say
   the target supports Fast-20 to avoid any nasty surprises?

Answer:
  I hope we don't need to. Present initiator adapters I know about handle
  synchronous negotiations without involvement of the system software.
  These adapters also do not read the INQUIRY data. If the bit is put
  in the INQUIRY data, therefore, the adapter will either a) need help
  in synchronous negotiations from the system (i.e. to tell it what
  transfer period to use) or b) it will have to read the INQUIRY data
  itself (to find out what transfer period to use).
  Choice a) will add complexity to system software and choice b) will
  add complexity to the adapter. Neither choice is desireable.

  Therefore I hope that either 1) we find that sending a current device
  a 48ns and 24ns transfer period request is an easily recoverable "error",
  or b) someone finds a way to solve the problem without adding complexity
  to adapters or system software.
                                     Giles Frazier
                                     IBM Austin
                                     gfrazier at ausvm6.vnet.ibm.com




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