|[6 earlier articles]|
|Re: C compiler pointer management on DSPs derek@_NOSPAM_knosof.co.uk (Derek M. Jones) (2019-09-28)|
|Re: C compiler pointer management on DSPs email@example.com (David Brown) (2019-09-29)|
|Re: C compiler pointer management on DSPs firstname.lastname@example.org (Kaz Kylheku) (2019-09-30)|
|Re: C compiler pointer management on DSPs email@example.com (George Neuner) (2019-10-03)|
|Re: C compiler pointer management on DSPs firstname.lastname@example.org (2020-02-27)|
|Re: C compiler pointer management on DSPs email@example.com (2020-02-28)|
|Re: C compiler pointer management on DSPs firstname.lastname@example.org (2020-02-28)|
|Date:||Fri, 28 Feb 2020 02:33:56 -0800 (PST)|
|References:||19-09-003 19-09-004 19-09-006 19-09-007 19-09-009 19-09-015 19-09-017 19-09-018 20-02-024 20-02-025|
|Injection-Info:||gal.iecc.com; posting-host="news.iecc.com:2001:470:1f07:1126:0:676f:7373:6970"; logging-data="98767"; mail-complaints-to="email@example.com"|
|Keywords:||architecture, history, comment|
|Posted-Date:||28 Feb 2020 12:27:44 EST|
On Thursday, February 27, 2020 at 7:03:27 PM UTC-8, rob...@dodo.com.au wrote:
> On 2020-02-28 09:23, firstname.lastname@example.org wrote:
> > Machines not so well designed require masking off the appropriate
> > bits before operating with them.
> Who can say that the CDC machines (7600; 70 series, etc) were not
> well designed?
> They were intended to be fast, and to carry out operations on
> words (of 60 bits).
CDC machines are designed for fast floating point number crunching.
They are not necessarily designed for fast character manipulation,
as that is supposed to be a relatively small part of the work.
The hardware/software tradeoffs were different so many years ago.
My favorite one has always been how the IBM 704 (and I believe
later 36 bit machines) read in cards. The read row-wise, each row
into two 36 bit words, leaving off 8 columns. This is also the reason
why Fortran (fixed form) uses columns 1-72.
Anyway, after the compiler reads in a card row-wise, it has to
convert to columnwise (six characters per word), including converting
to the appropriate character code. But it presumably saves a lot of
logic in the card reader, where it would be expensive and could be
done in software. The 7094 was the high-end number cruncher at
the time, including its use for S/360 emulation during its development.
But actually, as well as I know, the more usual way to run such
machines was to copy cards to tape, presumably in a cheaper machine,
so that the fast machine didn't waste so much time.
I don't know about the 60 bit machines, but there are stories
about C compilers for Cray machines using 64 bit char.
As with the CDC machines, Cray machines are designed for fast floating
point, and not so fast for fixed point.
[This is getting rather far from compilers but would be totally on-topic
in alt.folklore.computers. -John]
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