David M. Ensteness (denstene_at_mac.com) wrote:
> Not all 68030s were 32 bit, some were "32bit clean" and therefore could =
>
> run 7.6 and some were not and were stuck at 7.5.5.
That's a completely different issue. The MC68030, like its predecessor,
the 68020, had a 32 bit data bus, and this had nothing to do with being
"32-bit-clean". It also had an 32 bit address bus, but early versions of
Mac OS used only 24 bits for addressing memory, so the remaining 8 bits
of a pointer could be used for other things. Some Macs based on the
68030, such as the Mac IIx or SE/30, had a ROM that wasn't 32-bit-clean,
i.e. it used the previously unused 8 bits for its own purposes. When
Apple introduced 32 bit addressing, those Macs where left in the cold
until Apple released a patch that replaced the non-32-bit-clean parts of
the ROM.
- Michael
Michael J. Hussmann
E-mail: michael_at_michael-hussmann.de
WWW: http://michael-hussmann.de
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