On Nov 25, 9:32 pm, tortoise <[email protected]> wrote:
> And BTW there was also a separate MMU chip for earlier MMU-less 68k (? > '020?) The Macintosh II had a 68020 with an AMU (?) (IIRC) chip which could be updated to the PMMU. My understanding is the the 68K emulator built into the PPC Macintosh ROMs emulates a 68020. So the hooks for this kind of system must still be in the operating system at that time. The thing that surprises me is that the OS could detect a 68040 and then use the 68020 system in which a PMMU may be absent. Perhaps if the OS does not detect a PMMU it assumes it is running on a 68020 or earlier? It would all depend on how Apple built those case statements (or equivalent). Jeff Walther -- ----- You received this message because you are a member of the Vintage Macs group. The list FAQ is at http://lowendmac.com/lists/vintagemacs.shtml and our netiquette guide is at http://www.lowendmac.com/lists/netiquette.shtml To post to this group, send email to [email protected] To leave this group, send email to [email protected] For more options, visit this group at http://groups.google.com/group/vintage-macs Support for older Macs: http://lowendmac.com/services/
