Re: SCSI ID vs. unit ID

Knot to my Knowledge.

They used a sort of inverse SCSI numbering for optical back then. I had to decode it when I built Frankie II and Frankie III because we had as many as 4 DVD-RAM drives on the same SCSI string. (Get it wrong and IBM i think all the drives are the same one!) I believe if you set the jumpers for 12 the device became address 3. Something like that anyway.

The tape as you see must be device 0 and has no jumpers installed (Unlike Optical). The load source disk then is address 6 and I believe that is the only one that mattered. All hard disks needed to be higher than that. That thing only accepted 4 drives though given my other experiments I do suspect that if you found a way to extend the SCSI cable and added a 5th and 6th unit they might function. Just keep incrementing the SCSI address.

I think the unit number will more likely match the sequence they were added to the machine.

- DrF

On 1/17/2022 8:51 AM, Patrik Schindler wrote:

Hello,

I'm wondering if there is any mathematical correlation of the SCSI ID of a device on the sole physical SCSI bus of my model 150, and the associated Unit Numbers to be seen in SST.

Device | ID | Unit
------------+----+------
Load-Source | 6 | 1
Other Disk | 5 | 3
CD-ROM | 3 | 6
Tape | 0 | 5

Can anyone shed some light here?

:wq! PoC