Re: bunch of pedants

jacob navia wrote, On 19/03/08 16:33:
lawrence.jones@xxxxxxxxxxx wrote:
jacob navia <jacob@xxxxxxxxxx> wrote:
This is similar to their "trap representation", "one's complement" or
"sign magnitude" stuff... Nobody has ever seen those machines, there are
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
no implementations but

"... an implementation *could* exist" and there they go.

DEC's Vax floating-point formats have trap representations, as does IEEE
floating-point (signaling NaNs).

All FPUs have "trap representations" then. A nan will generate a trap
on Intel processors if the corresponding flag is cleared in the
control word. Great.

I believe there are a few more implementations than just the VAX an Intel processors. Something about my having used other implementations (where the processor did not have an FPU so all floating point was done in software) suggests you are wrong. You are also completely misrepresenting what Larry said.

Unisys mainframes use one's complement
integers.

You are out of date. As far as the UNISYS processors for sale
today, they use all Intel processors. See:

http://www.serverwatch.com/hreviews/article.php/3304111

for example.
In any case, it WAS used EONS ago in UNIVAC processors. As I said
before your information is not current.

No, you said, "no one has ever seen those machines." You are clearly wrong since even you admit that the machines were built and I'm sure you will not claim that everyone who ever used them was blind.

Nearly all floating-point formats use sign/magnitude. They're not nearly as chimerical as you think.

Maybe, but here it is used without any reference to floating point.
As far as I can see there isn't a single machine that uses one's
complement that is in use today.

So are you going to change you claim to, "there are no current implementations" instead of the clearly incorrect claim of "no one has ever seen those machines"?

The same for sign magnitude. This is a representation used in the IBM
7090, and it is really completely out of date unless you happen to live
in the sixties... The 7090 was produced in 1959.

As a general point you might be surprised about how long machines and processors continue to be used after they go out of production. So instance I know of a contract that was one which would involve modifying software for a processor that had gone out of production 5 years earlier and that another customer had plans to keep the kit going for another 20 years, i.e. 25 years after the processor was no longer manufactured.
--
Flash Gordon
.

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