A couple of DRAM memory stick questions ??
William Case
billlinux at rogers.com
Wed Sep 30 16:03:40 UTC 2009
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
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