robin wrote:
>>>> The 704 family offered double precision, too; it was not fully
>>>> implemented in hardware, but the hardware assisted it, and the
FORTRAN
>>>> compiler sup****ted it.
>>> It had to, in order to meet the standard.
>> There was no FORTRAN standard until long afterwards.
> IBM set it.
So your argument is that the 704 hardware had to implement
double-precision floating-point in 1954 in order to sup****t FORTRAN IV,
which didn't even come out until 1962 (two hardware generations later)?
>>>>> But for most work, little difference between 36 bits and 32 bits.
>>>>> But that's no measure, anyhow. The appropriate measure is
>>>>> the number of mantissa bits and range of exponent.
>>>> They add up to the word size, one way or the other.
>>> Not relevant; what's im****tant is the breakdown --
>>> and in particular, the number of mantissa bits.
>> In order to make any sense of your argument, I can only assume that you
>> do not know what the words "relevant" and "mantissa" mean. Kindly look
>> them up.
>
> The term "mantissa" has been used since the early days of computers
> to describe part of floating-point number.
>
> Are you having a bad day?
Either you are attempting to argue that the size of the fraction and the
size of the exponent are each more im****tant than one another, while
simultaneously maintaining that word size has nothing to do with the
issue either way, or else you are simply misusing words.
>>>> In any case, the
>>>> S/360 had significantly fewer effective fraction bits (21) in single
>>>> precision than the 7094 (27).
>>> Leaving only 7 bits for the exponent. In other words, a reduced
>>> range of exponent, which the S/360 corrected.
>> Having trouble with subtraction, are we now?
>
> When I last looked, 27 + 1 + 7 + 1 = 36.
Are you under the impression that the 704 series had a 35-bit word with
a parity bit?
>>>> The _whole_ S/360 architecture was copied, but, whereas the
8/16/32/64
>>>> two's-complement, byte-addressable data architecture has become
>>>> universal, the S/360 floating-point design was never used outside of
the
>>>> context of full S/360 compatibility, and the modern descendants of
the
>>>> S/360 now offer the vastly superior IEEE-754 as an alternative. Note,
>>>> too, that floating-point has become nearly a dead issue in the S/360
>>>> world; the z/OS FORTRAN compiler is decades old, and several
generations
>>>> out of date.
> You're overlooking, PL/I, which for which z/OS has a recent compiler.
PL/I is not a major player in the raw-science market; if it were, IBM
would have implemented PL/I sup****t for the (now dead, like every other
attempt to put the 360 family back into the high-performance-computing
market) 370 vector processor.
>>> The S/360 was not copied in its entirety,
>> Problem state was.
>
> Only the original, not the revised hardware, as I previously stated
(below).
Indeed, even the TS instruction was not implemented.
>>> and even in those
>>> cases where it was not copied in its entirety, the
>>> original hex floating-point design was retained
>>> (without guard digit on double, with zero for underflow, etc)
>> I'm sure IBM spent all that money upgrading all those machines without
>> payment just for fun.
>
> AFAIK, no-one else followed suite.
Because they couldn't afford to.
>>> Strange, we got along well with F.P.
>>> And both machines that we subsequently obtained used
>>> the original hex floating point (without guard digit, etc).
>
>
>>> It is clear that it was not the problem that you imagine.
>> It is clear that it wasn't a problem for /you/.
>
> It wasn't a problem for anyone in an extensive institution.
It demonstrably was a problem. IBM spent a fortune fixing what could be
fixed (note that it had to implement the change on at least seven
different machine types), the literature was full of problems introduced
by the S/360, and, in the end, the S/360 and follow-up lines were never
more than marginally successful in the supercomputing arena.
> I didn't buy anything. But I would point out that those
> "cheap" systems had superior real-time performance, with
> multiple resister sets and processor states for handling
> interrupts.
>
>>> And if it was as bad as you claim, how come they
>>> never implemented something better?
>> They did. In 1967,
>
> No they didn't. I was referring to clones in which the guard digit
> on d.p. was NEVER provided. [see above]
>
>>>> the literature was awash with the subject.
>
>>> Such as?
>
> Still no instance?
Gee, somehow I can't find my old computer magazines from the mid-60's. I
guess my mother threw them out with my comic books.
>>>>> How would you have done it better ?
>
> Still no answer?
I was in Junior High when these choices were being made. All I know is
that they were found inadequate in the field by many customers.
--
John W. Kennedy
"But now is a new thing which is very old--
that the rich make themselves richer and not poorer,
which is the true Gospel, for the poor's sake."
-- Charles Williams. "Judgement at Chelmsford"
|
