ITEM: Q7884L

Terminator type for SCSI-2 Fast/Wide Single Ended

Question:

Env:    AIX 3.2.5, Model 980b, Seagate external SCSI drive

Desc:   Customer needs to know if he should use a Passive, 
        Active, or Forced Perfect Terminator to connect his 
        Seagate 4Gb drive which is connected to his SCSI-2
        Fast/Wide SE adapter.

Action: The terminator that is needed is 52G9907.  This is a 
        forced perfect terminator (FPT-18+).

        In June 1991, IBM introduced Forced Perfect Termination
        (FPT) terminators.  These terminators lifted the
        restriction so that the full seven devices could be 
        attached to the SCSI bus.  All terminators shipped since 
        mid-1991 use this active termination technique.

   Terminators:

   non-FPT: a terminator that uses the older passive method of
            termination.  Internal/External SCSI bus was limited
            to two external devices.

   FPT-3  : a terminator that actively terminates only three of
            the SCSI bus lines: ACK, REQ, SEL.

   FPT-18 : a terminator that actively terminates 18 lines of the
            SCSI bus, including the eight data lines.  This
            terminator is no longer manufactured.

   FPT-18+: a terminator that actively terminates 18 lines of the
            SCSI bus.  This terminator replaces the FPT-18.  This
            FPT is functionally equivalent to the FPT-18 and is
            fully interchangeable with the FPT-18.

  The SCSI-2 F/W Single Ended adapter uses the FPT-18+ termination
  on the external bus and FTP-3 termination on the internal bus.



Support Line: Terminator type for SCSI-2 Fast/Wide Single Ended ITEM: Q7884L

Dated: January 1995 Category: N/A

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