I have just changed my cumana 300 to a proper atapi cd, because of
being unable to install Risc BSD

I aml getting problem with a number of errors during start up and panic
unable to mount root, I think I still
 have compatibilty problems with my drive since it gives a page of
atapi start /init  errors, immediatly after rd0 = 1440k (or some thing
like that). What concerns me about  the drive is that it was fitted
with a risc os floppy driver, which it does not function without under
risos. My brothers disc required no driver, for his CD, is their a
clear statard for ATAPI , and are all ATAPI drives normally supported
by RISCBSD.

Also is the setup master slave/critical for riscBSD mine is set CD
slave / 2G hard drive master, why is acd0, and not acd1 . 

Any ideas 

boot dev  /dev/acd0
swap /dev/wd0b

kernal from CD