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From: Vincent Manis on 11 Nov 2009 01:14
On 2009-11-10, at 22:07, Vincent Manis wrote:
> On 2009-11-10, at 19:07, Steven D'Aprano wrote:
>> In fact, in Inside Mac Vol II, Apple explicitly gives the format of
>> pointers: the low-order three bytes are the address, the high-order byte
>> is used for flags: bit 7 was the lock bit, bit 6 the purge bit and bit 5
>> the resource bit. The other five bits were unused.
I inadvertently must have deleted a paragraph in the response I just posted. Please add: The pointer format would have caused me to write macros or the like (that was still in the days when Apple liked Pascal) to hide the bit representation of pointers.
From: greg on 11 Nov 2009 04:32
Vincent Manis wrote:
> That's my point. I first heard about Moore's Law in 1974 from a talk given
> by Alan Kay. At about the same time, Gordon Bell had concluded, independently,
> that one needs extra address bit every 18 months
Hmmm. At that rate, we'll use up the extra 32 bits in our
64 bit pointers in another 48 years. So 128-bit machines
ought to be making an appearance around about 2057, and
then we'll be all set until 2153 -- if we're still using
anything as quaintly old-fashioned as binary memory
addresses by then...