On Thursday, June 04, 1998 6:03 PM [log in to unmask] wrote:

I am presently running one SCSI drive on my system and I want to add two
more. When I added the first it boots to it and not my original drive.
What I need to know is what determines which drive will be c: and which
will be d:, e:.
Thank you
Richard Marcinkowski

SCSI devices have device id assignments, usually accomplished by
putting jumpers on appropriate pins.  Some older SCSI adapters have
BIOS that expect a certain ID to be bootable.  The most common devices
searched for bootable files are ID zero and one.  You do not say which
adapter you are using, but any late model Adaptec or similar adapter will
allow you to enter the BIOS setup screen and designate the boot device.
I usually set the boot device id to be 6, since device id has something to
do with contentions, and 6 has higher priority than zero.

If you don't have documentation, SCSI device assignments typically are
binary values represented by individual pins, each pin being a power of 2.
They usually are read right to left.  (Turn this primitive schematic on its side!)

* *  = this pin is 1
* *  = this pin is 2
* *  = this pin is 4
* *  = if the device is a wide SCSI or ultra SCSI, this pin is 8

Cover as many pins as you want to with jumpers, add the values of the covered
pins, and this equals the device id.  Don't assign a device the same id as the
adapter, which usually is ID 7.

Tom Turak
tturak at ralgi dot com