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From: n...@cam.ac.uk
Newsgroups: comp.lang.fortran
Subject: Re: how to declare doubles in f95
Date: Thu, 29 Jan 2009 18:58:43 +0000 (GMT)
Organization: University of Cambridge
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References: <0b898c8f-5866-4942-bf2b-171655d6658a@r15g2000prh.googlegroups.com> <ron-shepard-D7D3BE.09224829012009@news60.forteinc.com> <glsi6q$r0a$1@smaug.linux.pwf.cam.ac.uk> <ron-shepard-1EBB22.12392629012009@news60.forteinc.com>
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In article <ron-shepard-1EBB22.12392629012...@news60.forteinc.com>,
Ron Shepard  <ron-shep...@NOSPAM.comcast.net> wrote:
>
>> "Many"?  And "common"?  Not really.  The only ones that I can think
>> of were CDCs and Crays, all of which were extremely specialised
>> supercomputers that sold in very small numbers.  What else were you
>> thinking of?
>
>There were also the fortran programmable attached processors that were 
>fairly common in the 80's.  These included the FPS-164 and FPS-264 
>machines which I used.  Certainly if you count every computational 
>scientist and engineer who used a CDC, Cray, ETA, SCS, or one of these 
>attached processors in the 80's, you would get a high percentage, 
>probably over 90% of us.  Not only were these machines sold to 
>individual groups and local departments, but there was also a number of 
>national supercomputer centers (NSF, DOE, DoD) which gave access to 
>almost everyone who applied.  If that >90% estimate is correct, then 
>"common" would be the correct description, right?  My feeling is that 
>scientists in the UK (your address) had wide access to these kinds of 
>machines earlier than they did here in the US.

90% of who?

Most of the coprocessor compilers I saw took a 'conventional' view
of precision, but I didn't see many as those coprocessors never
really took off.

>> Ones using 48 bits for single and 96 for double were probably more
>> common.  Once upon a time ....
>
>On the other hand, I don't know anyone who used a machine like this.  I 
>think Harris computers used 3-byte and 6-byte data, which is almost what 
>you are claiming, but I think there were fewer of these machines than 
>the types described above, and they were almost certainly less commonly 
>used.  There were no national supercomputer centers based on Harris 
>computers, for example.  I personally never used one, but I exchanged 
>code with collaborators who did, and wrestled with their integer*3 and 
>real*6 declarations.

The ICL 1900 range was perhaps the main one, but nowhere near the only
one.  I think it took that word size from Ferranti.


Regards,
Nick Maclaren.