🚀 go-pugleaf

In <41dejm$d1p@sundog.tiac.net> Jim Williams <williams@tiac.net> writes:

>Dan.Pop@mail.cern.ch (Dan Pop) wrote:
>>In <Pine.SUN.3.91.950821100405.5161B-100000-100000@spad.eng.auburn.edu> >
>>The bitness of an architecture is not defined by the size of the external
>>data bus, period.  
>>
>
>Now I'm wondering if he used the word "external" anywhere.  I
>won't go looking.

No need.  The internal data paths in the 8088 are 16-bit, so he was
obviously talking about the external data bus.
>
>Will you agree that 1) memory is slower than cpu, and 2) most
>programs don't fit in cache?  If this is true then the external
>bus is generally the bottleneck. 

Not necessarily.  You can write programs where the external bus is the
bottleneck, but this is not automatically true in the general case.
I/O bound and cpu bound programs are at least as common as memory bound
programs.

>I'm perfectly happy with a
>definition of bitness which revolves about the bottleneck... 

But you're obviously missing the fact that the bottleneck is application
specific (and some applications can be affected by more than one
bottleneck).  For someone generating fractals or doing data
compression, the cpu is the bottleneck.  And guess where is the
bottleneck for the "tar" and "cp" commands?  How about "ftp" and "rcp"? :-)

>In
>fact that seems like a very good definition to me -- the bitness
>of a machine is the path width of that portion of of the machine
>which happens to be the usual bottleneck.  

Too bad your definition is rendered useless by the fact that there is no
usual bottleneck.  When memory started to become a real bottleneck, the
chip manufacturers introduced the built-in cache.

Dan
--
Dan Pop
CERN, CN Division
Email: Dan.Pop@mail.cern.ch 
Mail:  CERN - PPE, Bat. 31 R-004, CH-1211 Geneve 23, Switzerland