Path: utzoo!utgpu!news-server.csri.toronto.edu!mailrus!uunet!ncrlnk!ncrwic!encad!entec!jlohmeye From: jlohmeye@entec.Wichita.NCR.COM (John Lohmeyer) Newsgroups: comp.periphs.scsi Subject: Re: Wangtek 5150ES SCSI behaviour Message-ID: <632@entec.Wichita.NCR.COM> Date: 8 Aug 90 14:34:00 GMT References: <450@bohra.cpg.oz> Reply-To: jlohmeye@entec.UUCP (John Lohmeyer) Organization: NCR Corporation, Wichita, KS Lines: 33 In article <450@bohra.cpg.oz> als@bohra.cpg.oz (Anthony Shipman) writes: >I have noticed some odd behaviour with a Wangtek 5150ES. The configuration is > AHA1542B controller > XT4380S Maxtor disk > 5150ES > >The format program in the ROM on the 1542B lists all of the SCSI IDs found. >When only the disk drive is connected it just lists the drive as ID 0. When the >tape is connected it lists the disk as ID 0 and the tape as all the IDs 1-7. > This sounds like an ID conflict. Your 1542B and tape are probably both using the same SCSI ID. Assuming the 1542B is at ID 7, when it polls for SCSI devices it starts at ID 0 and works up through the IDs. If your tape is also strapped to ID 7, the 1542B will find it at ALL unoccupied IDs. (It could also find it at ID 0, if the Maxtor disk was not faster than the tape.). Why does this happen? Because during SELECTION phase the initiator (1542B) puts out both the ID it is selecting and its own ID (for example, ID bits 7 and 1). The tape which is also on ID 7 sees its ID bit (7) and the ID bit of a phantom initiator (1). Thus the 1542B thinks there are tapes at all IDs (except those occupied by faster devices) and the tape thinks there are 1542Bs at all IDs. Strange, but it actually works fine so long as there are only 2 devices in the system and they consistently use one set of IDs. Try setting your tape to another ID. -- John Lohmeyer J.Lohmeyer@Wichita.NCR.COM NCR Corp. uunet!ncrlnk!ncrwic!entec!jlohmeye 3718 N. Rock Rd. Voice: 316-636-8703 Wichita, KS 67226 SCSI BBS 316-636-8700 300/1200/2400 24 hours