| T.R | Title | User | Personal
Name | Date | Lines |
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| 690.1 | Anyone else seen this one ? | BBPBV1::WALLACE | john wallace @ bbp. +44 860 675093 | Tue May 06 1997 11:22 | 8 |
| That URL may need a - in it: try dan-0411.html
And while we're on the subject, anyone seen anything definitive on the
alleged MMX "feature" which screws up systems where MMX apps and FPU
apps timeslicing allegedly overwrite each other's MMX/FPU context ?
regards
john
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| 690.2 | DIGITAL hardware has had a few bugs, too | XDELTA::HOFFMAN | Steve, OpenVMS Engineering | Tue May 06 1997 11:43 | 18 |
|
: Do Alpha's suffer from Math bugs ??
Please see HUMANE::DIGITAL note 5276.* for a discussion of this.
I would tend to avoid making any public comment about any of Intel's
microprocessor problems, as these public comments could easily come
back to haunt DIGITAL later.
DIGITAL has had cases of problems in a processor or microprocessor
design -- I know of various examples over the years, which I will
refrain from mentioning here for obvious reasons. (These problems
typically have hardware or software fixes or workarounds when the
problem is identified, and are thus not visible to users.)
The current Intel Pentium-II bug appears fairly obscure when compared
with the original Pentium FP bug.
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| 690.3 | it's all 1's and 0's to me. | RDGENG::ATTWOOL | | Tue May 06 1997 12:11 | 3 |
|
..I guess they do. Now what was that date ? ;^(
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| 690.4 | | BIGUN::nessus.cao.dec.com::Mayne | A wretched hive of scum and villainy | Tue May 06 1997 19:18 | 16 |
| Re .1:
MMX uses the same registers as the FPU. The reasoning is that if you put more
registers in, you'd lose backwards compatibility in a big way, like for instance
a context swap not saving the MMX registers. If the same registers are used,
then a context swap which currently saves the FPU registers will also
conveniently save the MMX registers with no extra work needed, and the OS
doesn't know or care whether you were doing FPU or MMX stuff at the time. This
specifically avoids the problem you stated.
The obvious downside is that your code can't do MMX and FPU work at the same
time. This may or may not be a problem.
This is what I've figured out from reading popular magazines.
PJDM
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