I'm not sure this can be done with an older mac, but... On an older pc
I installed windows xp, then did some work to remove the windows logon and logoff screens and so on. I replaced the windows shell with winuae.
Essentially when you turn it on,the machine appears to boot straight into amiga os3.9.
Perhaps you could do something similar, have mac os boot straight into eau and amiga os3.9? I'm not a mac person so I don't know if this is possible. If someone wants to send me an older mac, I can give it a a
try and report my results.
Steven
