I believe that pseudo-sync is synchronized thus not asynchronized.
However, is pseudo-sync also called 'asynchronous mode'?
i've put some evidence that it is called 'asynchronous mode' at the
end of the post in 2 chunks each marked <extract>...</extract>
The evidence that led me to my belief that pseudo-sync is synchronized
and not asynchronized is below, all the way down, up to the 2
<extract>s.
a disclaimer is at the end
Based on the references below i've concluded that async really means
separate clock, not derived. However, since the introduction of
pseudo-sync / pseudo-synchronous memory, some manufacturers have
called
pseudo-sync 'async' (without the quotes) which is wrong(even with
quotes is wrong), as you can't suddenly change and completely
contradict the traditional meaning of the word. And there is
absolutely
no way for that meaning of async to change, since it's de facto (been
in common usage for years) and de jure (set in law, coined many moons
ago no doubt).
I will follow with further proof that pseudo-sync is sync (and thus
can't be async because async means not sync - so it's either one or
the
other)
I went to my BIOS and set the clock for my memory bus to 100MHz,
(note,
my RAM is 266 DDR-SDRAM i.e. 133*2 MHz.
I ran Si Sandra and it told me that my RAM was at 266MHz = (2*133MHz)
multiplier of 4/3 x
So that means that my RAM which is DDR-SDRAM (the S standing for
synchronous) was operating at (4/3) times my FSB, that is a
pseudo-synchronous rate.
Pseudo-synchronous (keith and frank agree) is when the said clock's
speed is derived by a non-integer multiplier or a divider(divisor?)
that is 1/[insert non-integer here] like 1/2.5 (often stated as 2/5)
So my multiplier of 4/3 (note it's top heavy, thus a multiplier not a
divider) of 1.33x is pseudo-sychronous, and my RAM is DDR-SDRAM
SD= ***synchronous*** dynamic.
And my DDR-SDRAM was taking my FSB=100 as input, multiplying that by
4/3 to get 133MHz and then the RAM was writing/reading data onto the
memory bus at DDR thus 133*2=266MHz So it took the 100, multiplied
it, then DDR'd it.
note: yeah, i know with FSB=100MHz and RAM at 133MHz, i'm not making
use of the extra speed that i'm running my RAM at. But my processor is
1.3GHz and since i've got an AMD Athlon, I guess my multiplier is
locked at 13. Thus If I increase my FSB to 133(for max RAM
efficiency),
it would overclock my processor. I will probably unlock the
processor's multiplier (big hassle and risky) then set my FSB to
133MHz
and my multiplier to 10x, I will be overclocking my processor by
30GHz(no big deal!). My AGP @ 1/2x and PCI @ 1/4x should be ok.
References - these threads explain async, sync, and pseudo-sync
[1]
Re: Asus SP97-V question (9th december 2000)
http://tinyurl.com/4n3mx
note: pseudo-sync is explained here but all the way to the end, keith
and frank use different definitions.
(please see disclaimer, this is my understanding - which think is
correct - of what keith and frank said. I don't intend to put words
into their mouths)
Keith says pseudo-sync is a case of sync
Frank says it's a case of async
Keith's definition from years of experience and based on the
traditional definition of async which i tyhink he would argue has not
changed and can't refer to a derived clock. asynchrous clocks are 2
separate clocks, not derived from each orther,
no multipliers or dividers
"Asynchronous clocks need not have
any frequency relationship and therefor have no phase
relationship"
"They are *ASYNCHRONOUS*. There is no phase alignment."
(so that is why keith says pseudo-synchronous / pseuso-sync is not
async -
he says it is sync as it uses a derived clock like x1 or x 2/5 or 4/3
(i'm not sure if he used the term derived clock)
Frank's definition is from manuals and glossaries, he defines
pseudo-sync as a case of async.
in the 37th post of this thread "Subject: Re: Recommendations on
cheap
AT motherboard" frank gives a lot of evidence from his
manuals.
[2]
Re: Cyric MII 333 problems (from message 12 in thread) 21st Jan 1999
http://tinyurl.com/5v4nl
note: pseudo-sync explained brilliantly by keith.
[3]
Re: Recommendations on cheap AT motherboard (12 October 2001)
http://tinyurl.com/4qpxt
note : keith and frank still disagree on whether pseudo-sync is
async.
Frank gives lots of evidence from manuals in the 37th post of the
thread.
Extracts giving evidence that pseudo-sync = 'async mode'
extract from an overclockers website article
www.overclockers.com/tips1039/index02.asp
<extract>
"You should now have noted that a FSB of 133 MHz and one of 166 MHz
both produce the same memory speed of 333 MHz for DDR memory as a
result of the multiplier change in value at 166 MHz. The difference
between the two cases being the first is in an asynchronous mode of
operation while the second is in a synchronous mode. "
My thinking, is that he's saying
a)FSB 133 RAM (333=166*2) Mult=1.25
b)FSB 166 RAM (333=166*2) Mult=1
he calls 'a' async (from the threads mentioned below, I know that b
is
sync and a is pseudo-sync as pseudo-sync is mult by an non-integer or
by 1/[non-integer] )
Thus, since b is pseudo-sync and this guy called it 'asynchronous
mode'
I guess that pseudo-sync is the same as asynchronous mode.
</extract>
and more evidence that pseudo-sync is 'asynchronous mode'
http://forums.amd.com/index.php?s=76b91b820399d27c78b4ccdd5528cb7a&show
topic=18694&st=0&#entry191509
or
http://tinyurl.com/4mq2u
<extract from="AMD forum">
"On the other hand, if you want to keep the RAM frequency in 266Mhz
(by
SPD) or change to 333Mhz, you'll be forced to run in asynchronous mode
(FSB:DRAM ratio= 4:6 or 4:5), "
</extract>
notice also, that he's talking about DDR RAM (the guy mentions it
elsewhere. Also, I think 266MHz in our times smacks of DDR 133*2).
DISCLAIMER
disclaimer: my references make mention of keith and frank's
discussion.
Since their discussion was very long, I summarised my understanding of
their statements. I do not mean to speak for them, I have done my
best
to state their points and where they differ as accurately as possible,
to the best of my understanding. Just take my comments on their
comments as a general guide at best, and if you want to know their
exact comments, I included references to the threads they spoke in,
and
I included many quotes which I hope I haven't taken out of context.
I am not an engineer nor do I have any practical experience with PCBs
or chips. I just started reading about this stuff last week. So please
don't consider my words authoritative!! Anything i've stated that has
been derived largely from my brain , i've been careful to precede with
'i guess' or 'i think'(note the small i), unless i've backed it up
with strong
evidence. Since i've been composing in the wee hours and am posting
it at 5am, there may be the odd silly mistake, but since i've repeated
myself so much in this post so as to make my points as strongly as
possible, the rest of the post will show the silly mistake to be a
slip up and not a misunderstanding. hopefully, any misunderstandings
will glare out from the post (along with the eccentricity). I'm being
careful 'cos i'm stating other peoples' statements a lot on a subject
i started reading last week as a hobby, and at 5am i'm dizzy and more
prone to slip ups.
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