G4

mac os 8.5 was the first mac os that had predominantly ppc code but this carried on well in to os 9

>>Also, when did they discontinue classic boot capabilities into OS 9? <<

i am not entirly sure what you mean with this tough if you mean to ask what was the last macintosh able to boot in os 9 its the MDD which apple ran queitly for a while in 2003 before shufffeling it to the grave