How close are the simh emulators to the real hardware's floating point? How
exct is the emulation of FPU's?
Does simh emulate the real hardware close enough that you can use it to
analyze the original hardware floating point processors? (For those that
actually had FPUs instead of doing it in software).
Or does it do it using "modern" methods (IEEE style FPUs) that could
calculate different results than the original hardware did?
It;s probably not a big deal for most users, but if the simh FPU hardware
might operate any different;y than the real hardware it should at least be
On Mon, Oct 17, 2016 at 1:50 PM, Leo Broukhis <l...@mailcom.com> wrote:
> Dijkstra is above reproach; I try to compare the averages.
> Having eps^2 = eps is cute, but, given that the idea didn't spread to
> other pre-IEEE f.p. implementations nor to IEEE (it is possible to
> iteratively square a number x with 0 < abs(x) < 1 down to 0, given enough
> iterations, denormals or not), it appears that the Electrologica floating
> point turned out to be impractical.
> On Mon, Oct 17, 2016 at 11:35 AM, Paul Koning <paulkon...@comcast.net>
>> > On Oct 17, 2016, at 2:26 PM, Leo Broukhis <l...@mailcom.com> wrote:
>> > > I think that the same answer applies to your narrower question,
>> though I didn't see it mentioned specifically in the documents I've read.
>> > That's somewhat comforting; I'd hate to think that the BESM-6
>> programmers were substantially sloppier than their Western colleagues. :)
>> As you probably know, Dijkstra was a whole lot more disciplined than the
>> vast majority of his colleagues.
>> > > For example, the treatment of underflow and very small numbers in
>> Electrologica was novel at the time; Knuth specifically refers to it in a
>> > > footnote of Volume 2. The EL-X8 would never turn a non-zero result
>> into zero, for example.
>> > For most but not all values of "never", I presume. What was the result
>> of squaring the number with the least representable absolute value?
>> The least representable positive value. See the paper by F. E. J.
>> Kruseman Aretz that I mentioned.
>> > > I think IEEE ended up doing the same thing, but that was almost 20
>> years later.
>> > Are you're thinking about denormals?
>> I think so, but I'll be the first to admit that I don't really know
>> floating point.
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