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From: winders@aux.support.apple.com (Scott Winders)
Newsgroups: comp.sys.mac.hardware,comp.sys.mac.system
Subject: Re: Internal vs. External?  Which one wins?
Message-ID: <44888@apple.Apple.COM>
Date: 17 Sep 90 18:41:22 GMT
References: <6947.26f4a5e4@umiami.miami.edu>
Sender: nntp@Apple.COM
Organization: Apple Computer, Inc.
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In article <6947.26f4a5e4@umiami.miami.edu> gross@umiami.miami.edu (JD144) 
writes:

> If I have a Mac SE with an internal HD with a system, and I then attach
> an external SCSI HD with a higher SCSI ID number than the internal and 
> its own system folder...shouldn't the drive with the higher SCSI ID boot 
> before the drive with the lower ID number?  Or does the internal drive have > some sort of precedence over the external drive?


Here is the correct order of devices checked during the startup sequence:

1. Floppy drive 0 (internal or right side of Macintosh II).
2. Floppy drive 1 (external or left side of Macintosh).
3. Floppy drive 2 (Macintosh SE with third floppy drive).
4. Startup device selected via the Startup Device cdev (this may include 
   SCSI or NuBus startup devices).
5. SCSI devices beginning with ID 6 and ending with ID 0.
6. NuBus startup devices.

Both the Inside Macintosh V and the Macintosh Family Hardware Reference 
manuals  state that the internal SCSI device is checked before any other 
SCSI device, regardless of SCSI ID.  This is NOT True!  Unless the 
internal SCSI device is selected as the startup device via the Startup 
Device cdev it has no special priority during the startup process. 

Scott Winders
internet: winders@aux.support.apple.com
AppleLink: winders.s@applelink.apple.com