[comp.sys.mac.hardware] The real story

fdm@WLV.IMSD.CONTEL.COM (Frank D. Malczewski) (05/24/91)

In article <266621.283C3281@cmhgate.FIDONET.ORG> Adam.Frix@p18.f20.n226.z1.FIDONET.ORG (Adam Frix) writes:
>Somebody, please!  Tell me:
>
>why do you need a **ROM SWAP?**  You need to change some code concerning how the System runs, correct?  You need new ROMs to do this??????


Many moons ago, a post appeared on the net that explained about the difficulty
of providing 32 bit cleaness for 24-bit unclean ROMs.  Granted that this was
not an official post from Apple, it probably does not hold a lot of water,
but here is what it said (this is dated 23 May 1989, and had the subject
line "Re: System 7.0 & 32 Bit Mode)  (maybe Apple thinks we've forgotten... :-)


-----------------------------------

Just to set the record straight on the 32 Bit Mode discussions: although
large parts of the ROMs are 32 Bit Clean, and can run in 32 bit mode,
there are several crucial areas which are not. Most important of these is
the Memory Manager, which initializes the System Heap at boot time, BEFORE
any system patches can be installed... It would
be very difficult (and very slow) to change heap formats at system patch
time, and it would require patching out the entire Memory Manager and
several other pieces of the toolbox, using up large amounts of precious
physical RAM space.

Although I could expound on this stuff forever, I'll summarize: under
System 7.0, existing Mac II/IIx class machines will continue to run in 24
Bit Mode. Eventually, Apple will release new ROMs (for new and/or existing
machines) that will support 32 Bit Mode. System 7.0 WILL be able to run
with these ROMs (trust me :-)).

I hope that this will end the confusion...

------------------------------------

...Anyway, that's what was posted.  So perhaps this is why all of the
clamoring for new ROMs.  An issue that is still being debated TWO YEARS
later (at least we've got System 7.0 now!!!  :-)

Just what did he mean by "for new and/or existing machines" anyway?

--Frank Malczewski                        (fdm@wlv.imsd.contel.com)