Re: GS Crashing: copying files and Apple hi-speed SCSI (?)

[Bill North <north@spso.gsfc.nasa.gov>]

In article <CuDLFI.9x4@actrix.gen.nz> David Empson,
dempson@actrix.gen.nz writes:
>In article <32bb82$flq@paperboy.gsfc.nasa.gov>,
>Bill North  <north@spso.gsfc.nasa.gov> wrote:
>> You don't say how many devices you have daisy-chained
>> to the scsi card. If more than one, this could be a
>> termination problem. Ignore the scsi card docs.
>> Terminate both the first and last devices in the chain.
>
>That may help, but it definitely isn't correct.

Correct? Who's talking correct? With scsi, I'm talking magic. :)

>I have three drives
>on my Apple HS SCSI card, and only the last one is terminated.  It
>works fine, even if I turn off any one or two drives.  The drives are
>a Quantum 240LPS, a SyQuest 44 MB cartridge drive, and an old Rodime 60
>MB.

I also have three drives: a new Quantum 85, an old Quantum 80, and
a Syquest 44. The 85 and 44 worked great in any combination with
only the last drive terminated. Adding in the 80, I _must_ terminate
both the first and last or disaster strikes. These are on the Apple
HS scsi.

>The original Apple SCSI card isn't terminated, so you should have a
>terminator at the end of the chain, and if you have two drives, then
>also place a terminator between the first drive and the SCSI card.

Aha! But the docs explicitly say to not terminate between the card
and first drive if you have more than one drive. That's the part you
should ignore. Terminate both first and last, not just last as the
docs say. Do exactly as you say above.

>You can sometimes make things work by adding "too many" terminators
>(or having too few), or by rearranging the order of the drives.

Yup, magic.

If I get annoyed enough, maybe I'll get one of those new "smart"
active terminators that vary their termination level by actively
sensing the chain.

/*  Bill North -- north@spso.gsfc.nasa.gov  */