As stated, you'll need an appropriate file system to mount the discs. Make sure you assign a unique SCSI ID to the device, which in turn usually also needs to be set up identically in the file system. Terminate the last device on the external chain, and you may need to disable or remove the termination on the internal hard drive attached to the GVP A500+. Even though there's a SCSI cable attaching the drive to the circuit board, it is actually connecting between the control chip and the external port, thus the signal never gets out to the port with the terminator active. I have the exact same setup for my A500 and needed to do this to get the external CD-ROM drive recognized. BTW, if you're using WB 3.1, the CD filesystem included with the OS doesn't work very well with the GVP A500+. I ended up using CacheCDFS.
Good luck!
:-D
