Thanks poc;
Then it gets confusing again!
On Wed, 2009-09-30 at 10:53 -0430, Patrick O'Callaghan wrote:
On Wed, 2009-09-30 at 10:55 -0400, William Case wrote:
It's the data that's stored in units of 8 bits. When addresses are
stored then of course the same applies. When they're on the address
lines of the memory bus, they may be in groups of 16 or 32 or 64
(depends on the bus design). None of this matters to you as a
programmer.
Understood -- I think. Put another way, on a 64 bit machine if the
memory bus is 32 lines wide the data, or whatever, would flow with the
first 32 bits immediately followed by the second 32 bits -- right?
(I am trying to avoid discussing whether data flows on the rising edge
or falling edge of a clock tick etc.)
Note that the pedantic name for a group of 8 bits is
"octet". A "byte"
is the number of bits required to represent a character in some
encoding.
> When you say "chips" above I assume you mean cell, i.e. chip = cell =
> 1 capacitor and 1 transistor for storage of 1 bit.
A chip has a whole bunch of cells (in the millions these days). They
aren't the same.
Then what was Markku referring to when he said "A typical 64-bit DIMM
"stick" has eight 8-bit wide chips." The chip is one of the minute
black chips I can just barely see on a RAM stick --? That is what I
originally thought.
Markku's statement then implies that a 64 bit qword is stored in an 8 x
8 array of cells. True?
By the Way:
The definition of a 'word' seems to be all over the place.
With Intel, the definition I have read says a 'word' is 16 bits, a
'double word (dword)' is 32 bits, and a 'quadruple word (qword)' is 64
bits.
The specs for the 64 bit AMD CPU I used to have defined a 'word' as
whatever the machine said it was. In my case at the time, a 'word'
would have been 64 bits. ????
I raised the question of 'words' with my local Linux Users Group and
simply got caught in a long debate amongst them with huge digressions
that resolved nothing to my satisfaction.
--
Regards Bill
Fedora 11, Gnome 2.26.3
Evo.2.26.3, Emacs 23.1.1