olson@anchor.esd.sgi.com (Dave Olson) (05/16/91)
In <1991May15.001955.4146@corpane.uucp> herman@corpane.uucp (Harry Herman) writes: | In <41691@unlisys.in-berlin.de> rot@unlisys.in-berlin.de (Robert Rothe) writes: | I don't know anything about the SGI, but in order to use synchronous | SCSI, both the controller and the drive have to be willing to do it. | We purchased a disk drive once that was willing to do synchronous | SCSI, but since the controller was not willing to do it, we had to | jumper it off. I also do not know if you can do both synchronous | and asynchronous SCSI on the same cable or not. If not, then all | drives on the cable AND the controller would have to be willing to | do synchronous SCSI. | | Harry Herman | herman@corpane Well, this is partly correct. Until very recently, due to confusing language in the SCSI 1 spec, almost NO targets initiated synchronous negotiations. Therefore the SGI driver didn't handle it. In 4.0, the standard SGI SCSI driver DOES handle target initiated synchronous negotiations, but only if you have the newer version of the SCSI chip. The new version is found on all 4D25's, all 4D35's, the most recent 4D20's, and machines with the IO3 (power channel board). The hinv command will show either WD33C93, or WD33C93A. The A version is newer. The older chip has a bug that prevents target initiated sync negotiations from working on our hardware. You can mix synchronous and async scsi devices on the same bus, with no problems at all (a good thing, since only the newest tape drives support sync mode!) on systems that support sync scsi. -- Dave Olson Life would be so much easier if we could just look at the source code.