Re: 8500 won't boot if unused drive disconnected
On 21 Mar, this message from Chris Tillman echoed through cyberspace:
> On Thu, Mar 21, 2002 at 10:49:59PM -0500, Michael D. Crawford wrote:
>> The short story: My 8500 won't boot if I remove a drive that should not
>> be accessed during boot. I would like to see if I can get the Mac to
>> boot without it.
>
>> I have two theories about this:
>>
>> - The ID 0 drive holds the internal bus terminator. Maybe if I got a
>
> This is definitely true.
Absolutely.
>> terminator I can mount on my ribbon cable, then things would work. Do
>> such terminators exist (this would mount on the internal ribbon cable,
>> not like the external terminators that have Centronics connectors on
>> them). Where could I find one?
>
> Sorry, I don't know.
Don't wste your money on a ribbon cable terminator. As long as you have
at least one drive on the internal cable, you _must_ have a drive
connected to the _physical_end_ of that cable, and _that_ drive needs to
have internal termination activated (look for the jumper settings; you
can find most any drive documented on the 'Net).
> But you have the right idea. Or, since your new
> drive has termination capability, you could terminate it and set it to
> address 0 with the jumpers.
^^^^^^^^^
That is not necessary. The drive can have any address on the bus (except
7, which is the controller). It needs to be physically on the end of the
cable, though.
>> - The Mac is loading the SCSI disk driver off my ID 0 drive, and that
>> allows the Mac to continue to boot.
>
> I don't think that's it. The drivers are loaded off the same disk they read.
Right. Drivers loaded off the disk come in to play during MacOS load
phase (typically on the grey screen with the mouse cursor). MacOS not
loading _may_ be a problem loading the driver, but than the driver is
not the problem: accessing the SCSI bus (missing termination) is.
Cheers
Michel
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