What makes an AMD chip 64 bit?

Mike Smith wrote:
I am curious how a 64 bit chip is able to run a 32bit OS and run 32bit
apps.

Simple. It has three modes, 64 bit, 32 bit and 16 bit. x86-32 CPUs only have
two modes: 32-bit and 16-bit. 32-bit OS's don't know how to switch on 64-bit
mode, so it runs (better than a current XP at the same MHz) in 32-bit mode.
In a 64-bit OS (such as Linux or the to-be-released-eventually Windows
x86-64), the OS knows how to put the chip into 64-bit mode. So the OS as any
64-bit programs run in full 64-bit mode, and if there are any programs that
don't run in 63 bit mode, the OS kicks the processor into 32-bit (or 16-bit,
if it's really ancient) mode for the timeslice of that process. Much like
current OS's kicking the CPU into 16-bit mode when you need to run a DOS
application.

[rest of trolling snipped]

--
Michael Brown
www.emboss.co.nz : OOS/RSI software and more
Add michael@ to emboss.co.nz - My inbox is always open

I am curious how a 64 bit chip is able to run a 32bit OS and run 32bit
apps. Sure, a 32 bit OS can run 16 bit apps, but Windows XP/2003 have
special versions of their OS for the 'real' 64 bit chips from Intel.

I have an AMD 2600+ chip even though I vowed to never buy Cyrix chips
again when they used the "+" standard and blurred the lines of Mhz
comparisos. I was disappointed when AMD started that crap. I am
leary of trusting what they are defining what 64 bit means to them.

What I am thinking is that they are going to run a 32bit OS no better
than a 32 bit processor and not be able to run a 64 bit OS at all.
Maybe a 3200+ will be faster in a 64 bit flavor than a 32 bit flavor
but will it be due to a 64 bit processor, or something else like more
"secret" megahertz. Maybe tweaking the core speed to fake us into
buying the 64 bit platform.

I have to be suspicious since they took the time to confuse us with
the fake benchmarking.

"Mike Smith" wrote in message
...
I am curious how a 64 bit chip is able to run a 32bit OS and run 32bit
apps. Sure, a 32 bit OS can run 16 bit apps, but Windows XP/2003 have
special versions of their OS for the 'real' 64 bit chips from Intel.

I am curious why we are back in the troll season
the REAL intel64 chips are going to use the same internal calls as the amd64
chips. So if you feel that amd64 is not 'real' then that also means that
intel is not 'real' and the comparison is 'real' cause you have 2 non
'reals' to compare.

I have an AMD 2600+ chip even though I vowed to never buy Cyrix chips
again when they used the "+" standard and blurred the lines of Mhz
comparisos. I was disappointed when AMD started that crap. I am
leary of trusting what they are defining what 64 bit means to them.

The + is in there for marketing reasons (by the rest of your post I can only
assume that your one of the people who has a NEED for that '+' to understand
what your buying)

What I am thinking is that they are going to run a 32bit OS no better
than a 32 bit processor and not be able to run a 64 bit OS at all.
Maybe a 3200+ will be faster in a 64 bit flavor than a 32 bit flavor
but will it be due to a 64 bit processor, or something else like more
"secret" megahertz. Maybe tweaking the core speed to fake us into
buying the 64 bit platform.

Yea, a 64bit processor is going to run 32bit software about the same as
32bit software.. Glad you got that down..

I have to be suspicious since they took the time to confuse us with
the fake benchmarking.

I dont think they do fake benchmarking, Apple and MSI are the only 2
companys that have done this recently..

"Mike Smith" wrote in message
...
I am curious how a 64 bit chip is able to run a 32bit OS and run 32bit
apps. Sure, a 32 bit OS can run 16 bit apps, but Windows XP/2003 have
special versions of their OS for the 'real' 64 bit chips from Intel.

I have an AMD 2600+ chip even though I vowed to never buy Cyrix chips
again when they used the "+" standard and blurred the lines of Mhz
comparisos. I was disappointed when AMD started that crap. I am
leary of trusting what they are defining what 64 bit means to them.

What I am thinking is that they are going to run a 32bit OS no better
than a 32 bit processor and not be able to run a 64 bit OS at all.
Maybe a 3200+ will be faster in a 64 bit flavor than a 32 bit flavor
but will it be due to a 64 bit processor, or something else like more
"secret" megahertz. Maybe tweaking the core speed to fake us into
buying the 64 bit platform.

I have to be suspicious since they took the time to confuse us with
the fake benchmarking.



interesting, but you're bit off base. First, drop the MHz comparison.
Really, there's not much to it when comparing AMD's chips with Intel's. An
Athlon 64 3200+ wipes the floor with an Intel Pentium 3.2Ghz, and the Athlon
64 only runs at 2Ghz. Thats 1.2Ghz LESS. Pretty damn fine engineering if
you ask me. Intel only went with the Pentium 4's new architecture because
of its ability to scale very well in GHz. But put a 1.6 Ghz Pentium 4
against a Pentium 3 running at 933MHz, and the Pentium 3 kicks the Pentiums
4's arse. Not a very efficient architecture, but it does well once the Ghz
are cranked up. Here's a really good link about the Celeron Vs. Duron CPU's.
Its kills the MHz myth. Are Mhz important? Yes. Are they THE defining
point for performance of a CPU? Not at all! =)
http://www.anandtech.com/cpu/showdoc.html?i=1927

Onto the Amd's 64-bit Athlon. It has all the instruction set of x86, plus
many others such as 3dNow!, SSE, SSE2, and so on. But the main part is that
x86. You might have heard of the 386, 486 chips way back before the Pentium
name. The x86 is a 32-bit instruction set started with the 386, before that
was the 286 with 16-bits. 8088 i think was an 8-bit instruction set, but
i'm not sure on that one. So we've had 32-bit x86 cpu's since the late
80's. I think its time we went to 64-bit. Don't you? =)

Anyways, AMD's Athlon 64 has added on 64-bit instructions, called A64, to
the x86 instruction set. The only time most of these 64bit registers are
used is when a 64-bit operating system takes advantage of the extra
registers. Otherwise the (for the most part) lay dormant until that time,
and kicks the program into the x86 32-bit registers. So, say you buy an
Athlon 64 3200+ right now and install Windows XP Professional. Its a 32-bit
OS, so the 64-bit won't even matter. However, once Windows XP 64-bit comes
out for the Athlon 64, you can start using that 64-bit. And it WILL matter
in performance, if the programs you are using are recompiled for 64-bit.
32-bit programs will have to run in sort of an emulation mode, and will be
most likely slower. The cost of converting to the 64-bit future. But, in
2-3 years times, i'm sure a lot of people will have a 64-bit machine.

AMD converted to the PR rating (ie, 1700+, 2400+, 3200+, etc), to get away
from the MHz myth. If you saw a Pentium 2.4Ghz machine, and an AMD Athlon
XP 1.8Ghz (2500+), you'd think the 2.4GHz Pentium 4 would be a LOT faster
than the Athlon 1.8Ghz system...WRONG. The Athlon XP does more work per MHz
than the Pentium 4, and in most games/applications will run equal or even
faster than the Pentium 4 2.4Ghz.

So, there you have it. Personally, i'd wait for another 6 months before
upgrading to the Athlon64 chip. By then we'll see how the 64-bit scene has
progressed with respect to a Windows OS, as well as seeing how the
egg-frying Pentium 4 Prescott chip does. (140watts of heat!? Shesh! I hope
thats wrong!)

Oh, btw, to those of you who are anal....go ahead and correct me where i
might be wrong. =)

What about ATI and Nvidia and that whole driver issue(s)! ;p
Ed


Yea I forgot about ATI.. I didnt hear the scoop on NV.. Their drivers just
dont work so I guess it's a lie from the start

interesting, but you're bit off base. First, drop the MHz comparison.
Really, there's not much to it when comparing AMD's chips with Intel's.
An
Athlon 64 3200+ wipes the floor with an Intel Pentium 3.2Ghz, and the
Athlon
64 only runs at 2Ghz. Thats 1.2Ghz LESS. Pretty damn fine engineering if
you ask me. Intel only went with the Pentium 4's new architecture
because
of its ability to scale very well in GHz. But put a 1.6 Ghz Pentium 4
against a Pentium 3 running at 933MHz, and the Pentium 3 kicks the
Pentiums
4's arse. Not a very efficient architecture, but it does well once the
Ghz
are cranked up. Here's a really good link about the Celeron Vs. Duron
CPU's.
Its kills the MHz myth. Are Mhz important? Yes. Are they THE defining
point for performance of a CPU? Not at all! =)
http://www.anandtech.com/cpu/showdoc.html?i=1927

Onto the Amd's 64-bit Athlon. It has all the instruction set of x86, plus
many others such as 3dNow!, SSE, SSE2, and so on. But the main part is
that
x86. You might have heard of the 386, 486 chips way back before the
Pentium
name. The x86 is a 32-bit instruction set started with the 386, before
that
was the 286 with 16-bits. 8088 i think was an 8-bit instruction set, but
i'm not sure on that one. So we've had 32-bit x86 cpu's since the late
80's. I think its time we went to 64-bit. Don't you? =)

Anyways, AMD's Athlon 64 has added on 64-bit instructions, called A64, to
the x86 instruction set. The only time most of these 64bit registers are
used is when a 64-bit operating system takes advantage of the extra
registers. Otherwise the (for the most part) lay dormant until that time,
and kicks the program into the x86 32-bit registers. So, say you buy an
Athlon 64 3200+ right now and install Windows XP Professional. Its a
32-bit
OS, so the 64-bit won't even matter. However, once Windows XP 64-bit
comes
out for the Athlon 64, you can start using that 64-bit. And it WILL matter
in performance, if the programs you are using are recompiled for 64-bit.
32-bit programs will have to run in sort of an emulation mode, and will be
most likely slower. The cost of converting to the 64-bit future. But, in
2-3 years times, i'm sure a lot of people will have a 64-bit machine.

AMD converted to the PR rating (ie, 1700+, 2400+, 3200+, etc), to get away
from the MHz myth. If you saw a Pentium 2.4Ghz machine, and an AMD Athlon
XP 1.8Ghz (2500+), you'd think the 2.4GHz Pentium 4 would be a LOT faster
than the Athlon 1.8Ghz system...WRONG. The Athlon XP does more work per
MHz
than the Pentium 4, and in most games/applications will run equal or even
faster than the Pentium 4 2.4Ghz.

So, there you have it. Personally, i'd wait for another 6 months before
upgrading to the Athlon64 chip. By then we'll see how the 64-bit scene
has
progressed with respect to a Windows OS, as well as seeing how the
egg-frying Pentium 4 Prescott chip does. (140watts of heat!? Shesh! I
hope
thats wrong!)

Oh, btw, to those of you who are anal....go ahead and correct me where i
might be wrong. =)



There's also the issue of what u'r using ur comp to do. The current 64-bit
chips are server chips and are not designed for gamers. I'm personally
waiting at least a year (especially since I just built my PC this past
summer), but if I were interested in going to 64-bit chips, I'd still wait
for socket 939 chips and boards.
--
A7N8X Deluxe Rev 2.0 | 1007 Über | 1700+ @12 x 168 = 2.02Ghz @1.7v |
CorsairTwinX XMS 2700LL (2x256) 6-2-2-2 @2.7v | MSI GeForce4Ti4200 128MB
@280/584 | 3DMark=10,658 | CoolerMaster Aero7+ | Microcool Northpole | HS on
SB | Diode = 28/34°C | Socket = 35/39°C | Vantec Ion 400W

On Mon, 8 Dec 2003 20:26:42 +1300, "Michael Brown"
wrote:

Mike Smith wrote:
I am curious how a 64 bit chip is able to run a 32bit OS and run 32bit
apps.

Simple. It has three modes, 64 bit, 32 bit and 16 bit. x86-32 CPUs only have
two modes: 32-bit and 16-bit. 32-bit OS's don't know how to switch on 64-bit
mode, so it runs (better than a current XP at the same MHz) in 32-bit mode.
In a 64-bit OS (such as Linux or the to-be-released-eventually Windows
x86-64), the OS knows how to put the chip into 64-bit mode. So the OS as any
64-bit programs run in full 64-bit mode, and if there are any programs that
don't run in 63 bit mode, the OS kicks the processor into 32-bit (or 16-bit,
if it's really ancient) mode for the timeslice of that process. Much like
current OS's kicking the CPU into 16-bit mode when you need to run a DOS
application.

[rest of trolling snipped]


Is the 64 bit mode actually good as Intel's 64 bit mode? I would look
at the entire OS going from 64-bi-t-32-bit mode as a down side just
to run an app. 2000/NT (and probably 2003/XP) had a 16 bit subsystem
where the apps ran. The down side to the NT implementation was that
if one app crashed, they all did. Also, they were cooperatively
multitasked. MS got around this in 2000 if I remember but is more of
a moot point since there aren't many 16 bit apps out there any more.

I was just curious if AMD reinvented the "64 bit" term by doubling a
32bit with a clock tick or something.

So, is the IA64 version of Windows going to run on the AMD 64, or just
on Intel. And, this isn't an AMD question, but if you run the 64 bit
version of Windows, does every app have to be designed for use in that
kind of like the "Alpha" version of Windows?

Mike

On Mon, 8 Dec 2003 20:33:02 -0000, "rstlne" .@. wrote:


"Mike Smith" wrote in message
.. .
I am curious how a 64 bit chip is able to run a 32bit OS and run 32bit
apps. Sure, a 32 bit OS can run 16 bit apps, but Windows XP/2003 have
special versions of their OS for the 'real' 64 bit chips from Intel.

I am curious why we are back in the troll season
the REAL intel64 chips are going to use the same internal calls as the amd64
chips. So if you feel that amd64 is not 'real' then that also means that
intel is not 'real' and the comparison is 'real' cause you have 2 non
'reals' to compare.

I have an AMD 2600+ chip even though I vowed to never buy Cyrix chips
again when they used the "+" standard and blurred the lines of Mhz
comparisos. I was disappointed when AMD started that crap. I am
leary of trusting what they are defining what 64 bit means to them.

The + is in there for marketing reasons (by the rest of your post I can only
assume that your one of the people who has a NEED for that '+' to understand
what your buying)

Hey dickhead, if you don't care to answer the questions then don't. I
specifically hate the ****ing + thing and would rather know that AMD
has better performing chips, BASED ON ACTUAL MEGAHERTZ.

Obviously you don't have the ability to comprehend what you are
reading.

What I am thinking is that they are going to run a 32bit OS no better
than a 32 bit processor and not be able to run a 64 bit OS at all.
Maybe a 3200+ will be faster in a 64 bit flavor than a 32 bit flavor
but will it be due to a 64 bit processor, or something else like more
"secret" megahertz. Maybe tweaking the core speed to fake us into
buying the 64 bit platform.

Yea, a 64bit processor is going to run 32bit software about the same as
32bit software.. Glad you got that down..

Really? So I guess you are still running Windows 95 then, huh? I
guess XP and 2000 are just GUI updates in your world, right?

I have to be suspicious since they took the time to confuse us with
the fake benchmarking.

I dont think they do fake benchmarking, Apple and MSI are the only 2
companys that have done this recently..

I am new to this group but I already have someone to add to my
killfile.

On Mon, 08 Dec 2003 20:45:36 GMT, "Sean"
wrote:

interesting, but you're bit off base. First, drop the MHz comparison.
Really, there's not much to it when comparing AMD's chips with Intel's. An
Athlon 64 3200+ wipes the floor with an Intel Pentium 3.2Ghz, and the Athlon
64 only runs at 2Ghz. Thats 1.2Ghz LESS. Pretty damn fine engineering if
you ask me. Intel only went with the Pentium 4's new architecture because
of its ability to scale very well in GHz. But put a 1.6 Ghz Pentium 4
against a Pentium 3 running at 933MHz, and the Pentium 3 kicks the Pentiums
4's arse. Not a very efficient architecture, but it does well once the Ghz
are cranked up. Here's a really good link about the Celeron Vs. Duron CPU's.
Its kills the MHz myth. Are Mhz important? Yes. Are they THE defining
point for performance of a CPU? Not at all! =)
http://www.anandtech.com/cpu/showdoc.html?i=1927

My main complaint is that I still build my own systems and it is a
pain in the ass to not know what the hell you are supposed to set your
clock speed to. My best guess for my 2600+ with the 200 mhz FSB is
2.087 mhz. 167*12.5 (still guessing/testing). I started getting
frustrated for having to scour the web to find the right settings so
it would not get cooked and still perform where I needed it to.

For comparison reasons I don't care if the mhz numbers don't match up,
but for system upgrading/building, I want to know the right numbers.

Onto the Amd's 64-bit Athlon. It has all the instruction set of x86, plus
many others such as 3dNow!, SSE, SSE2, and so on. But the main part is that
x86. You might have heard of the 386, 486 chips way back before the Pentium
name. The x86 is a 32-bit instruction set started with the 386, before that
was the 286 with 16-bits. 8088 i think was an 8-bit instruction set, but
i'm not sure on that one. So we've had 32-bit x86 cpu's since the late
80's.

Is that as good as an Intel 64bit offering? Is that how they are
going to do it too? The reason I am asking is that there would be a
need for separate version of OS's if they didn't, unless MS is going
to offer support for both in one OS. (Remember the DEC/Alpha version
of Windows?)

I think its time we went to 64-bit. Don't you? =)

ABSOLUTELY!

Anyways, AMD's Athlon 64 has added on 64-bit instructions, called A64, to
the x86 instruction set. The only time most of these 64bit registers are
used is when a 64-bit operating system takes advantage of the extra
registers. Otherwise the (for the most part) lay dormant until that time,
and kicks the program into the x86 32-bit registers. So, say you buy an
Athlon 64 3200+ right now and install Windows XP Professional. Its a 32-bit

OK, you have answered my question about that. I wasn't sure if you
needed to run a 64 bit OS on it or not. I think I have an IA64 beta
someplace and I didn't want to run a beta OS for this particular
machine.

OS, so the 64-bit won't even matter. However, once Windows XP 64-bit comes
out for the Athlon 64, you can start using that 64-bit. And it WILL matter
in performance, if the programs you are using are recompiled for 64-bit.
32-bit programs will have to run in sort of an emulation mode, and will be
most likely slower. The cost of converting to the 64-bit future. But, in

Slower than what? Slower than XP 32 bit, or XP 64 bit apps?

2-3 years times, i'm sure a lot of people will have a 64-bit machine.
AMD converted to the PR rating (ie, 1700+, 2400+, 3200+, etc), to get away
from the MHz myth. If you saw a Pentium 2.4Ghz machine, and an AMD Athlon

I don't look at that as a myth. I look at it as the truth. If they
are going to market their chips as "as good as Intel's xxxx chip" then
they will forever be in their shadow. AMD has a great platform but it
is hard to compete with Intel's marketing arm. I always knew AMD was
better performing than Intel but I dislike not knowing the actual MHZ
speeds a chip is supposed to run at when working on hardware,
especially when it is easy to cook them, and there are a lot of
armcharil overclockers out there screwing things up then bringing them
in to the local chop shops so that they can accuse them of ruining
them.

XP 1.8Ghz (2500+), you'd think the 2.4GHz Pentium 4 would be a LOT faster
than the Athlon 1.8Ghz system...WRONG. The Athlon XP does more work per MHz
than the Pentium 4, and in most games/applications will run equal or even
faster than the Pentium 4 2.4Ghz.

So, there you have it. Personally, i'd wait for another 6 months before
upgrading to the Athlon64 chip. By then we'll see how the 64-bit scene has
progressed with respect to a Windows OS, as well as seeing how the
egg-frying Pentium 4 Prescott chip does. (140watts of heat!? Shesh! I hope
thats wrong!)

My main reason for this question is that I always try to buy
chips/boards that I will be able to upgrade and hang on to for a
while. Since it looks like we are at the end of the 32 bit era for
AMD I finally have to figure out what they are doing with the 64 bit
arena.

Oh, btw, to those of you who are anal....go ahead and correct me where i
might be wrong. =)

You may need to check with the first two respondents to my message who
are calling me a troll. (rstlne and Michael Brown)

Thanks for the response, much better than the troll lovers' responses.

Mike Smith wrote:
On Mon, 8 Dec 2003 20:26:42 +1300, "Michael Brown"
wrote:

Mike Smith wrote:
I am curious how a 64 bit chip is able to run a 32bit OS and run
32bit apps.

Simple. It has three modes, 64 bit, 32 bit and 16 bit. x86-32 CPUs
only have two modes: 32-bit and 16-bit. 32-bit OS's don't know how
to switch on 64-bit mode, so it runs (better than a current XP at
the same MHz) in 32-bit mode. In a 64-bit OS (such as Linux or the
to-be-released-eventually Windows x86-64), the OS knows how to put
the chip into 64-bit mode. So the OS as any 64-bit programs run in
full 64-bit mode, and if there are any programs that don't run in 63
bit mode, the OS kicks the processor into 32-bit (or 16-bit, if it's
really ancient) mode for the timeslice of that process. Much like
current OS's kicking the CPU into 16-bit mode when you need to run a
DOS application.

[rest of trolling snipped]


Is the 64 bit mode actually good as Intel's 64 bit mode?

x86-32 and IA64 are completely different. They're both full 64-bit
instruction sets, but that's about where the similaritites stop. x86-64 has
the advantage that it's basically identical to x86-32, so it's very easy for
many people to program for (and relatively easy to write decent compilers
for). IA64 is a VLIW machine that is almost impossible to program for
efficiently by hand. It needs a lot of help from a compiler to package
things up nicely for it to run fast. But it runs damn fast (though this is
more an implementation point than an architecture point).

I would look
at the entire OS going from 64-bi-t-32-bit mode as a down side just
to run an app.

It only does that if the app is 32-bit, and there's no performance hit (runs
just like a current Athlon XP, except faster). Given that you effectively
can't even run x86-32 apps (ie: normal Windows programs) on an Itanium, as
it's so damned slow (think Pentium 100 sorta speeds), means that it's a bit
of an advantage

2000/NT (and probably 2003/XP) had a 16 bit subsystem
where the apps ran. The down side to the NT implementation was that
if one app crashed, they all did. Also, they were cooperatively
multitasked. MS got around this in 2000 if I remember but is more of
a moot point since there aren't many 16 bit apps out there any more.

This is not my experience. I ran multiple 16-bit apps (16-bit Windows apps
mainly) under NT4. Some crashed, the rest didn't. Each ran under a different
virtual machine. Assuming a decent implementation of the OS, which is not
always a given from MS , the difference between a 64-bit application and a
32-bit one should be invisible. The main reason for the slowness of the
16-bit subsystem (which also included DOS apps running in 32-bit protected
mode) in NTx is that all hardware interaction and BIOS calls are
intercepted, checked, then emulated by the OS. This is not necessary under
x86-64, as no 32-bit Windows app can access hardware directly anyhow,
assuming you're not running 9x, so no emulation is necessary.

There's two possible ways that MS can do this implementation. The first is
to have the OS have both 64-bit and 32-bit DLLs. This would be pretty
wasteful, but would save any mode switching by the CPU (I don't think mode
switching is expensive, but I can't remember exactly how bad it is). The
alternative would be to have thunk 32-bit DLLs that just repackage the
parameters passed on the stack and then fire it off to the 64-bit DLL, which
does all the work. This could be a little bit complex, but nothing a few
thousand man-hours couldn't fix Doing it this way would impart a small
penalty for each DLL call (around the 20 cycle mark excluding mode switches)
but would save on bloat and unnecessary code.

I was just curious if AMD reinvented the "64 bit" term by doubling a
32bit with a clock tick or something.

Nope.

So, is the IA64 version of Windows going to run on the AMD 64, or just
on Intel.

There's going to be two versions of 64-bit Windows: one for IA64 (Itanium)
and one for x86-64 (Hammer). Neither will be able to run the OS for the
opposite chip.

And, this isn't an AMD question, but if you run the 64 bit
version of Windows, does every app have to be designed for use in that
kind of like the "Alpha" version of Windows?

For x86-64, no (as explained how the OS can kick back to 32-bit mode without
a performance hit). For IA64, technically no, but if you want to actually DO
anything in the next 10 minutes, yes. So IA64 is kinda like the Alpha
version of Windows, as you could get some x86-32 emulators for the Alpha
windows, but they ran dog slow.

--
Michael Brown
www.emboss.co.nz : OOS/RSI software and more
Add michael@ to emboss.co.nz - My inbox is always open