[G4] SCSI ID question

[Ron Steinke]

On 1 Mar, 2004, at 21:49, Donald Town Jr. wrote:

<< After popping two of the newer drives in and starting up, (Thinking 
I had
successfully changed a scsi id) I decided I better ask here for someone
to straighten me out on if that still applies to the different newer
drives.

Also, the profiler said one drive was on ata 1 and the other on ata 0.
Both had ID 0, and I don't know of that is allowable on that machine so 
I
shut it down to await clarification of what is 'doable' safely. >>

It appears that you have successfully installed the two IDE hard drives 
on separate bus ribbons. You should have no further problems except 
that attaching a slower device to the ribbon attached to a fast hard 
drive may cause the drive to operate at a slower speed than it is rated 
for. I would suggest attempting to link both drives on the same ribbon 
after identifying them as "Master" and |"Slave" drives. That would 
leave the second ribbon available for the CD and Zip drives. You may 
need to have custom length IDE ribbons built for you at a local 
computer store.

The SCSI socket on the mother board gives you the ability to attach up 
to eight SCSI devices to that circuit (SCSI IDs from "0" to "7" equals 
8 devices). The primary limiting factor here is the number of power 
connections that are available and the power output of the power 
supply. You also have the limitation of available mounting locations 
inside the G3 case - usually there is not space for more than three 
devices such as Zip drives, hard drives, and CD readers/burners in 
addition to the original equipment installed (Floppy drive, original 
hard drive, and CD drive).

As long as you provide the SCSI devices with different identities (no 
duplicate numbers), you should see each device as a separate icon on 
your desktop when you boot-up. You can then treat each device as an 
individual site and choose to store your data in whichever location you 
want. If you want, you can install separate operating systems on each 
drive and choose to start up from different drives as the need arises. 
Just remember to identify each drive as a separate identity.

Look for the SCSI identification bridge pins on the drives. They are 
usually identified by the letters "A0, A1 and A2" or just as "0, 1, and 
2" printed on the circuit board. "0" equals ID-1, "1" equals ID-2, and 
"2" equals ID-4. Placing bridges on the sets of pins in different 
combinations creates the SCSI identification, ie: no bridge equals 
SCSI-0, bridge on "0" equals SCSI-1, bridge on "1" equals SCSI-2, 
bridges on "0" and "1" equals SCSI-3, bridge on "2" equals SCSI-4, 
bridges on "0" and "2" equals SCSI-5, bridges on "1" and "2" equals 
SCSI-6, and bridges on all three ("0", "1", and "2") equals SCSI-7.

Good luck with your adventures into the world of SCSI.