The "stock" version of Apple's CD-ROM driver for MacOS 8.x (and probably all versions of "classic" Mac OSs) does not recognize the emulated CD-ROM of RaSCSI. At startup, the CD-ROM driver will send an unsupported command that is not supported by RaSCSI.

I believe this check was done to make sure that only CD-ROMs with Apple firmware were used.

There are a couple work-arounds:

• Install ResExcellence's CD-ROM driver hack (https://web.archive.org/web/20040404121044/http://www.resexcellence.com/hack_html_99/12-21-98.shtml)
• [Untested] Use a 3rd party CD-ROM driver. The CD driver that was distributed with Toast may be a good one to try.