🚀 go-pugleaf

In article <edm.724366309@wrs.com> edm@wrs.com (Ed McClannahan) writes:
> 
> >>>NeXTStep is said to not run on the Cyrix 486 chips because "they are
> >>>not real 486's".  No one has come up with a reliable reason _why_ NeXT
> >>>doesn't think they are "real 486's" or why NeXTStep won't run on them.
> 
> >>I don't have any real data, but I expect the problem is that the Cyrix
> >>chip doesn't have a floating point unit.  
> 
> >A 10/21/92 semi-official net posting on NextStep claims it runs on SXs:
> 
> The jist I got was that NeXTstep wants to maintain compatible File Systems
> between 680X0 and X86 platforms.  To do this, they needed to do a lot of
> byte swapping on the X86 platforms.  Since the 486 has a simple instruction
> to do it while the 386 does not, NeXT just went with the 486.


Well, we have come full circle.  According to Microprocessor Reports,
the Cyrix chip _does_ have the BSWAP instruction, so unless you have
more than just guesses that it doesn't, then my original statement
still holds:

*No one has come up with a reliable reason _why_ NeXT doesn't think
that they are "real 486's" or why NeXTStep won't run on them.*


There are *guesses* that it's because of performance differences, but
that doesn't seem to make too much sense.


There are *guesses* that it's because NeXTStep requires floating
point, but that doesn't seem to be the case.


There are *guesses* that it's because the Cyrix chip doesn't have the
BSWAP instruction, but it seems that Cyrix does have the instruction.


There are *guesses* that it's because of the Cyrix chip doesn't manage
the cache the same way, but know one knows if it is really different.


There are *guesses* that it's because of some of the new control flags
that the i486 has that Cyrix may not have, but know one knows if that
is really a difference.


I have posted all the hard facts that I know, but continuing to
*guess* what NeXT means by the "Cyrix isn't a real 486" phrase is
pointless.



Please, if _someone_ has hard info, post it and kill this thread.  If
you don't have hard info, then don't guess.


thanks

-wayne