Well, I can't say much from the Amiga side, but after playing around with Macs for a number of years, I don't think there were really any instances where instructions were _removed_ that broke software... I do remember there were a few specific issues when features were _added_ and a lot of software broke, like when the 68020 macs were introduced with onboard caches that broke some software that used self-modifying code, and when the 68040 was introduced with its onboard caches, I think it ended up breaking some software as well. This is all mac-related stuff, though, so I don't know if there were ever any similar issues over on the Amiga side. -Sean Caron (root(a)diablonet.net)