Apple Mac 8600 - Manual (Page 73)

Troubleshooting Symptom Charts/System - 10
During startup,
following message is
displayed, "This
startup disk will not
work on this
Macintosh model...."
1 Verify that startup disk is good.
2 Verify system software is version 7.5.5 or later (PM 8600/
200, 9600/200, 9600/233) or 7.6.1 or later (PM 8600/
250, 8600/300, 9600/300, 9600/350, WS 9650).
3 Do a clean install of system software.