🚀 go-pugleaf

In article <5160006@hpindda.cup.hp.com> mario@hpindda.cup.hp.com (Mario Arias) writes:
>
>
>A question concerning 3270 bisynch.  Does anyone know if an
>RVI followed by status sense response of "DEVICE BUSY" is 
>a legal response to a host device selection?  The 3274 
>Control Unit description manual indicates that it is,
>but it is not clear.
>
   The manual actually notes that WACK is the legal response
   according to Notes 2 and 3.             

   Actually, as long as the ABSOLUTE NEXT outbound sequence to
   the device (after the RVI) is an EOT, then an Specific Poll,
   this is an error.   

   Note 2 of the BSC Selection Addressing diagram specifically
   states that the device has pending status....EXCLUDING either
   Device End or Busy.   In other words, a device with ONLY Busy
   or Device End should NOT issue an RVI.

   If the status is only Device End, the device should send an
   ACK 0, reset it's DE status internally, and take the
   following command.

   If the status is Busy (which would obviously be exclusive of
   Device End), the device should return a WACK.   

>If a device is busy when a host tries to select it, should
>a WACK be used to respond or can the above mentioned 
>status sense message of "DEVICE BUSY" be used?
   
   As noted, if the ONLY status is Busy, the WACK is the proper
   response.   (Page 4.21 in my version of the Desc,
   Manual....but these haven't changed since the older 3271...)