68882 in a Mac II

[Phil Ronzone]

In article <4225 at pt.cs.cmu.edu> ralphw at ius3.ius.cs.cmu.edu (Ralph Hyre) writes:
>>... can I just pop the '881 out of my Mac II (A/UX) and drop in the '882?
>
>[no]	... The '882 has a larger saved register stack during
>	interrupts, which required a changed to the UDOT stack space
>	in A/UX 1.0.1 (the one which runs on the 68030).
>
>Didn't Motorola document a way to interrogate the FPC to ask how large its 
>stack and other frames will be?  If so, then it's too bad the NOBODY
>seems to have used it in their OS kernels, thereby requiring an OS upgrade
>when the '882 came out.  (on a Sun, we're told that dropping an '882 in
>will typically cause the u_area to be overwritten, with bad results.)
>					- Ralph W. Hyre, Jr.

Sure, Motorola documents these kinds of facts. The documentation is nice and
pretty and generally available just a few months AFTER the part is in
production and shipping. That means over a year after the part has had the
software frozen for it. (Only 50% tongue-in-cheek ...)

The very first PMMU Apple ever (tried) to plug into the early prototype
Mac IIs didn't fit in the socket! Someone at Motorola decided it needed
a few more power pins ... and somehow the one-page tech note missed us.

I suppose the day that future hardware parts are built exactly to the
specifications written before the part is produced,

will be the day that future software will have to be built exactly to
the specifications written before the software is produced (assuming
this industry STARTS writing specifications before writing code)
:-) :-) :-)


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