neese@adaptex.UUCP (07/06/90)
>/* ---------- "Trouble in stalling ISC 2.2 with mu" ---------- */ > >Well, I was trying to install Interactive Unix 2.2 on my system, >and ran into a problem. I hooked up a new SCSI drive as the boot >drive (SCSI ID 0) and had my old drive as ID 1 (tape is ID 2). >The cable I am using is a 4 connector SCSI 50 pin internal >cable going from the host adaptor to drive 0 to drive 1 which >is properly terminated. The tape is on another (external) bus. >Anyway, the host adaptor (Adaptec 1542A) hangs on one of the first >disk accesses. I tried hooking up the new drive as the only drive >(changing terminations) and it installed OK, but after that and >rebuilding the kernel to make sure, on going back to the two >drive configuration, I still get hangs. Anyway, to make >a long story short, can you use a 4 connector SCSI cable with >3 devices (host adaptor, 2 disks), leaving one of the middle >connections loose. I know this works for ST506, ESDI and floppies, >but SCSI has it's own specs. Any other suggestions? Also could there >be some sort of conflict between the drives? I am running a >Fujitsu M2263SA as drive 0 and a HP 9754XS as drive 1. I also >have parity checking disabled. Would enabling this help? Proper termination in the above setup woud be; The drive on the end of the cable connected to the internal SCSI adapter connector should be terminated and the drive connected to the end of the SCSI cable that is connected to the external connector should be terminated and the terminators should be removed from the adapter card. You can have any number of open connectors between the adapter connector and the first SCSI device. BUT you cannot have a connector open at the end of the SCSI cable unless it is less that 3.5" from the last connector connected to a SCSI device. I beleive the Fujitsu drive has synchronous negotiation as a jumper option. Make sure to disable the drive's ability to negotiate for synchronous protocol. If you want to run sync, then enable the adapter's sync protocol jumper and let it negotiate for sync protocol. Make sure that the external cable you are using is anywhere from 75 to 100 ohm impedence. This is vary important as impedance matching is critical when using the internal and external connections. Make sure that the external cable is well seated on the adapter connector. This is usually the problem as most AT's allow the external connector to protrude only the minimal amount needed to make a good connection. Roy Neese Adaptec Senior SCSI Applications Engineer UUCP @ uunet!swbatl!texbell! {nominil,merch,cpe,mlite}!adaptex!neese