Assigning ID3 to CD rom drive

Assuming that you made no internal changes to the 8600 and that the ribbon and power cables aren't defective, the drive may be faulty. The address certainly didn't change itself, so if disks stopped mounting, the problem may be with the drive or the disks that you're attempting to read. Are the disks that wouldn't mount CD-Rs/CD-RWs or are they commercial music or software CDs? If the former is the case, some older CD-ROM drives have trouble reading certain brands of media. With my older Macs, I had better luck using the CD-Rs that had an aqua colored reflective surface, as opposed to the typical mirrored look. If you're having problems with commercially manufactured disks, the drive may not be compatible. I've run across this situation, when installing third-party ATAPI drives in the G3 Macs. Did the original Apple/Matshita drive experience the same problem? Are you sure that neither the data nor power cable has an intermittent short that's affected by the physical position of the cable? What brand is the CD-ROM drive? Did you attempt to find an Apple/Matshita 24x SCSI CD-ROM drive, when the original failed?

It would help greatly to know the exact brand and model of CD ROM. It's usually accomplished by setting jumper pins, but the exact setting (unless you're lucky and it's printed on the drive) will depend upon the model drive. E.g., [http://sdd.toshiba.com/main.aspx?Path=ServicesSupport/JumperSettings/SCSICD-RO MDVD-ROMJumperSettings]

Use the Table Limnos provided, or re-derive from fundamental principles, thus:

The lowest numbered Addr pin counts for one
The next higher counts for 2
The next higher counts for 4
(if present, the next higher counts for 8)
Jumper present adds that value, absent adds nothing
Add-em-up.

0.1.1 sets address 3 (2 plus 1), presuming the lowest Addr bit is rightmost.

CD drives will always be listed as unmounted unless there is a readable CD in the drive. If you set no Address jumpers when removing from the case, it is Address Zero, which, if on the same Bus as the Factory Hard Drive, conflicts with the factory Hard Drive. Your Mac may have a second higher-speed Bus for Hard Drives only, avoiding the conflict.

I've used Toshiba (ATAPI) Combo drives in the beige and B&W G3s, and they're supported for Apple Disk burning and will boot from the "C" key. I've used an older Sony (not Apple/Sony) SCSI CD-ROM drive in one of my Power Macs without any problems. As for an older Toshiba SCSI drive, I can't say. If the drive doesn't have jumpers for Termination Enable and Termination Power, that could be the problem. Obviously, a used Apple/Matshita 24x SCSI CD-ROM drive would be the ideal solution, but the purchase and shipping expenses exceed the value of an 8600.

With XPostFacto involved, you can boot to the (normally unbootable) 10.3 Installer CD. Once XPostFacto is in use, you should always use XPostFacto (not System Preferences > Startup Drive or Control Panels > Startup Drive) to Set the Startup Drive.

XPostFacto can be run from any OS 9 Hard Drive OR OS 9 System/Install CD. It can also be run from a Mac OS X Hard drive. Keep it readily available on your Hard Drives (it won't fit on a diskette, unfortunately).

For routine maintenance, I'd want an optical drive to boot from the OS X installer disk, so Disk Utility can scan and/or repair the hard drive.