Path: utzoo!utgpu!news-server.csri.toronto.edu!cs.utexas.edu!wuarchive!julius.cs.uiuc.edu!apple!portal!cup.portal.com!DrBob From: DrBob@cup.portal.com (Robert A Rethemeyer) Newsgroups: comp.sys.amiga.hardware Subject: Re: Archive tape drives for sale Message-ID: <34190@cup.portal.com> Date: 22 Sep 90 21:39:22 GMT References: <1990Sep20.203248.4070@agora.uucp> <92650@srcsip.UUCP> Distribution: na Organization: The Portal System (TM) Lines: 47 In article <92650@srcsip.UUCP> carpent@SRC.Honeywell.COM (Todd Carpenter) write s: >AIGH!! You people talking about SCSI tape drives are JUST doing it to tortur e >those of us who are stuck with the A2090a controllers! You are SO cruel! > >So, that brings on a serious question: Has anyone managed to get the A2090a >patched up so it can be used with a SCSI tape? Sort of. There seem to be two problems with using the 2090As with SCSI tapes that I hit while writing my own tape handler. One, usually referred to as the "write phase" bug, causes a lockup when attempting to do a scsidirect write to the tape (there's no problem with reads). Bob Mitchell disassembled the 2090A driver and discovered that this one can be circumvented by asserting address bit 24 of the address of the data to be written. My code works ok using something similar to the following: cmd->scsi_Data = (UWORD *) (&tapedata | 0x01000000); The other problem is tougher. When reading from the tape and writing to the disk (such as when doing a file restore from tape to disk), the 2090A seems to loose its marbles, as though it is stuck in a loop. HOWEVER, this problem only happens when the disk involved is on the SCSI bus with the tape drive. If the disk is instead on the ST506 connection, then this problem does NOT occur. Also no problem if restoring to floppy or RAM:. I should say that I have used only the 3M MCD-40 tape drive- maybe the 2090A likes other brands better. As long as we are discussing scsidirect circumventions, I'll mention what I had to do to get the Supra 4x4 running Series-II v1.10 to work. First, the byte count in scsi_Length must be zero. I know it sounds strange, but it works. Second, the process doing the scsidirect requests *must* run at a higher priority than the Supra "supradirect.device" task. The task runs at priority 10, so the process had better run at 11 or above. Both these things have been reported to Supra. I've finished my tape handler, and I sent it to the Amiga moderator 2 weeks ago, but it hasn't shown up in c.b.a yet. (what's going on??) The handler has been tested with the 3M MCD-40 tape drive running on the CBM 2091, Supra 4x4, and the CBM 2090A/ST506 combination. It may well run with other drives/adapters, but I don't have access to the hardware to test it. =-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=- Bob Rethemeyer //"This is obviously some strange DrBob@cup.portal.com -or- // usage of the word 'safe' that I hadn't ..!sun!portal!cup.portal.com!DrBob // previously been aware of." - A. Dent