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HP OpenVMS Systemsask the wizard |
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The Question is: I have a 4mm DAT drive, known working and recently removed from an OpenVMS system. I have it connected to (don't laugh) an old Amiga 2000. Writing my own software I am able to issue SCSI packets to the tape drive, but can't seem to get a particular beha vior I enjoyed under VMS, using $QIOW with the "Read Virtual Block" function. Namely, I could read blocks off the tape without knowing their sizes in advance, by requesting the LARGEST POSSIBLE blocksize -- 65536 bytes -- and picking up the "actual size" out of the IOSB after the read completed. Issuing simplistic SCSI "READ" commands to the tape drive nowadays, I seem to have to specify the correct block size "up front" in order for the read to succeed. I'm thinking that the VMS tape-driver programmer s knew more about SCSI than I do, and that they knew a SCSI-command sequence that I don't, to get the drive to behave "the VMS way" I've described above. So... can you tell me the specific sequence of SCSI commands issued to a 4mm DAT drive in order to p erform the following VMS DCL commands -- INITIALIZE/OVERRIDE=(OWNER,ACCESS,IDENT) devicename: MOUNT/FOREIGN devicename: MOUNT devicename: label -- and for a QIO[W] IO$_READVBLK specifying a record (block, buffer) size of 65536 bytes? I'd really appreciate knowing the magic sequence(s). Thanks in advance. The Answer is : Please contact the Amiga Wizard for assistance with this question. The OpenVMS Wizard is not in a position to provide SCSI programming tips for the Amiga operating system, and is entirely unfamiliar with the Amiga system and its SCSI interface(s). The particular series of SCSI commands generated by OpenVMS can vary over OpenVMS releases, and is considered undocumented. (The lowest level of the SCSI interface that is documented is in the area of the GKDRIVER, see the I/O User's Reference Manual for details.) Available tools include SYS$ETC:SCSI_INFO, available in V6.2 and later OpenVMS releases. Please start with the SCSI specifications for the particular version of SCSI in use on the Amiga, and (if you have access to these) the OpenVMS Source Listings CD-ROM set and a SCSI bus analyzer.
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