| Re: Big Endian, Little Endian. |
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Group: comp.lang.c++.moderated · Group Profile
Author: Jonathan Thornburg [remove -animal to reply]Jonathan Thornburg [remove -animal to reply] Date: May 11, 2008 07:52
> Not possible. Depending on the CPU and the memory system, the byte
> order may be dynamic, or it may vary among sections of memory. Or it
> may be "mixed endian" (not strictly big or little), or have no
> endianness.
Sohail Somani taggedtype.net> wrote:
> Wow. Do you have an example?
The Digital PDP-11 and VAX systems (= arguably the most popular and
influential minicomputers in the world for the 1960s-70s and 70s-80s
respectively) were little-endian for integers, but stored floating-point
numbers in memory in a mixed-endian order. A floating-point number
(either IEEE or one of the VAX-only formats) which might be the register
bit-pattern 0x87654321 would be stored in memory with bytes in the order
(if my slight dim memories haven't faded too badly) first 2, then 1, 4,
3, 6, 5, 8, and finally 7. The reasons for this go back to backwards
compatability with early PDP-11 systems with had 16-bit memory buses.
--
-- "Jonathan Thornburg [remove -animal to reply]"
soton.ac-zebra.uk>
School of Mathematics, U of Southampton, England
"Space travel is utter bilge" -- common misquote of UK Astronomer Royal
Richard Woolley's remarks of 1956
"All this writing about space travel is utter bilge. To go to the
moon would cost as much as a major war."
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