Chris Craddock writes:
|
| . . . I am glad that the wizards have made it all work out, but in terms
of functional needs,
| 64-bit addressing is overkill on a cosmic scale.
|
Let us hope so.
Computing---informatique, informatica, whatever---is a fairly new
discipline; but one red thread that runs through its brief history is that
nothing is ever big enough for long. External names at most eight
characters in length, DDNAME values at most 44 characters in length, varying
(halfword current-length prefixed) strings at most 32767 bytes in length,
fullword values not larger than 2147483647, etc., etc., have all proved to
be too small.
Moreover, address spaces first 24 and then 31 mibibytes in size have quickly
proved to be too small, not for every application but for some crucial ones.
The moral of this anecdotage is that notionally "reasonable" maxima have in
our history always been outgrown much too soon.
Another obvious point to make is that this storage is virtual not real
storage. All of it need not be backed up, and what is backed up need not
even be connected (contiguous); and still another perhaps not quite so
obvious one is that when four-byte addresses are inadequate, there are
compelling architectural reasons for moving to eight- and not five-, six-.
or seven-bye ones.
Those of you who have not used the 'new' 64-bit facilities need to learn to
do so. Moreover, time spent mastering them will have been used to better
advantage than time spent dismissing them as unrealistically sized.
John Gilmore
Ashland, MA 01721-1817
USA
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