I'm afraid you are somewhat off base, yes. A simple recompile will give you a working programme, so long as nothing in the programme is dependent on the size of items in memory, especially pointers. Currently all pointers are 32 bits, and a lot of structures used in the OS assume this, so you need glue code to adjust this in a 64 bit environment.
However, I believe that OSX was written with 64 bitness in mind, so most of the work has already been done, but for certain no one will be sure until after they have actually run a large number of existing programmes on 64 bit hardware and software, as with most development of existing code, the vast majority of the time is spent testing.
Michael</strong><hr></blockquote>
Ah, I'd forgotten about pointer math. I guess I've been spending too much time with Java lately. Thanks for explaining that.
Thanks for the lesson in CPU's... It clears up many falsehoods that keep getting spouted about. But, after reading everything you wrote about 32 vs 64bit CPU's... What I'm not sure I understand is WHY?
Why do we need to move to a 64bit system... It seems from what you've written most things will not see any major pop in performance due to the 64bitness of the CPU. The pop will come from other factors such as Mhz etc (as with any new CPU).
So what real world computer tasks could benefit with a computer running 1 64bit over say 2 (or more) 32bit cpus. Unless building the new CPU as a 64bit isn't a 'big deal' and the chip designers are just doing it 'because it doesn't really matter one way or the other'.
The kernel and base OS design has built-in support for the following processor architectures, even if the machine code for every single cpu might not be included in current compiled versions:
PowerPC (dedicated code setpus for 601, 603, 603e, 603ev, 604, 604e, 750 (using different l2 cache configurations), 750cx, 7400 (using different l2 cache configurations), 7410, 7450 (using different l2/l3 cache combinations). Note the support for the 601. Neither the 7460 nor the 8500 are listet in currently available OS X versions. If the 7460 is more than just a 7450 with better fab process (different l2/l3 cache config for example) we should get an updated OS with the new machines. If the 7460 is very similar to the 7450 Apple probably won't add specific code for this CPU, 10.1.2 doesn't add specific 7440 code either (the 7440 is considered to be a 7450 with 0kb l3 cache, as far as I can see).
Intel x86 (dedicated code setups for i386, i486, i486sx, PentiumPro, PentiumII). Note the lack of support for the original Pentium CPU, this processor probably is considered to behave like a 486, no support for MMX. The P6 design has been separated in PPro and PII because of the different L2 configs, PIII and PIV use the same setup as PII. All this is needed for the Intel port of Darwin, for example, it does NOT mean that Apple will ever offer OS X on the x86 architecture. Athlon is considered to be 100% x86 compatible.
Intel Risc aka i860/i960 (i960 is considered to be 100% compatible with i860).
Motorola 68k (68030 and 68040 only). Note that 68000, 68010 and 68020 would not be able to run the OS X base system because of the lack of hardware support, like MMU and more... 68060 is considered to be 100% compatible with 68040.
Motorola 88k Risc (only one code setup for all CPUs)
HPPA / Hewlett Packard Precision Architecture (optimized for the 7100lc)
Sun SPARC (only one code setup for all CPUs)
Note that the system core has been designed to run on little and big endian systems (you will be able to comile it for Intel and other platforms). I can assure you that at least some parts of the core system have been prepared for 64 bit. The entire system core / UNIX layer (which is based partly on NeXTstep, OpenBSD and NetBSD) has been designed for 32 and 64 bit processors.
Anyway, as already mentioned by others it doesn't make sense for Apple to move to 64 bits, as only very few apps will take real advantage of the 64 bit registers, and I think that a powerful SIMD unit (like Altivec) is much more efficient in most cases than a 64 bit ALU.
BUT - if Apple has learned one thing from Intel, people don't care about the real facts. Look at the mhz myth, Intel needs mhz so much that they even reduce the cpus efficiency for the marketing (-> P4). Apple could use the 64 bit mode for marketing, they would be the first to offer a large number of 64 bit systems. They could say "well, we are still at 1.6 ghz (G5) while Intel is at 2 ghz (P4), but we have a 64 bit cpu instead of only 32 bits. Consumers are stupid, and that's why they'll believe it (why else are people buying Wintel machines?). The G5 will probably be faster than the P4, but not because of 64 bits but because of a better design (enhanced ALU, Ocean crossbar witch, RapidIO,...). But Apple can't use these facts for marketing, as the common consumer has never heard of "ALUs", "crossbar switches" or whatever. Remember the Nintendo64? All the hype they made with their 64 bit CPU, that's just the same...
One nice thing about the PPC architecture definition is a seamless 32-bit mode on 64-bit chips. This means you can run 32-bit software without any kind of an emulation hit on a 64-bit processor. So there isn't a reason to not go 64-bit, and there are a few apps where benefit would be seen in 64-bit mode -- particuarly server apps. A 64-bit G5 w/ OSX would let Apple compete with the big guys in the server market against the 64-bit SPARC, MIPS, IA-64, Alpha, Power3/4 and Precision processors. If (when) the G5 shows up it will be in the high end machines, and it will considerably extend Apple's reach into the workstation market where margins are even wider.
Not having a 64-bit processor, however, means that you are limited in those areas where you really do need one. Apple will go there, its just a matter of when.
Jeez louise. So if Apple is talking like the MHz gap is about to be closed - and the Apollo G4 is supposed to be a whole new kind of G4 with a thinner fabrication and a new bus and all this - what's the point of waiting for a g5? Like, if Jobs goes out and introduces new machines with a 266 bus, 266 ram (or whatever) and a new apollo g4, won't that be a considerable speed increase over the current models - like more than some new-fangled 64 bit processor that won't even effect any speed increases?
And if so then why all the focus on the G5? Is it the number? Is it because it can go to eleven? It's one more than a G4?
(Sorry if I'm mastering the obvious here - I've just been so caught up in the g5 frenzy that I'm starting to think the semantics of the change are more important than the actual change itself.)
Hell, if Apple brings out new powermacs with faster ram and faster buses, and dual processor machines over 1.2 Ghz, I'll take three, thanks very much (for work and home)!!!
<strong>The kernel and base OS design has built-in support for the following processor architectures, even if the machine code for every single cpu might not be included in current compiled versions:</strong><hr></blockquote>
Okay, but correct me if I'm wrong here, but this means Darwin can run on all the processors you mentioned, but mac applications and the aqua interface will not run on anything other than a powerpc? Is that right?
Is it possible to bring out an AMD-based Powermac without having to update all your software? (Don't think it is, but just wondering).
Thanks for the lesson in CPU's... It clears up many falsehoods that keep getting spouted about. But, after reading everything you wrote about 32 vs 64bit CPU's... What I'm not sure I understand is WHY?
Why do we need to move to a 64bit system... It seems from what you've written most things will not see any major pop in performance due to the 64bitness of the CPU. The pop will come from other factors such as Mhz etc (as with any new CPU).
So what real world computer tasks could benefit with a computer running 1 64bit over say 2 (or more) 32bit cpus. Unless building the new CPU as a 64bit isn't a 'big deal' and the chip designers are just doing it 'because it doesn't really matter one way or the other'.
</strong><hr></blockquote>
The cost of adding 64bitness to a processor is relatively small. Firstly it only affects the integer portions, the FPU and the vector unit already work with as wide or wider data paths, and the extensions of the ALUs to handle 64 bits is relatively simple, there is a bit of overhead for controlling the mode (32 or 64 bits).
The big advantage to 64 bits is not in any internal operations but in being able to logically address more than 4GB of memory. This may not seem like much of a limitation at the moment, but people handling large databases, complex rendering projects, some CAD systems, and a lot of scientific modelling, are already using more than that memory, and using 64 bits makes that a lot easier. Soon, however, many other users will be running systems, which, between several programmes running simultaneously, will approach that memory requirement.
The big advantage to 64 bits is not in any internal operations but in being able to logically address more than 4GB of memory. This may not seem like much of a limitation at the moment, but people handling large databases, complex rendering projects, some CAD systems, and a lot of scientific modelling, are already using more than that memory, and using 64 bits makes that a lot easier. Soon, however, many other users will be running systems, which, between several programmes running simultaneously, will approach that memory requirement.
Michael</strong><hr></blockquote>
BINGO!!!! A HA! Thank you so much for this. Now it makes sense to me why Apple is designing a 64 bit processor.
The image is of an SGI Octane in the middle of a set of Apple-branded crosshairs.
Okay, so that's no big revelation. But I've been writing Apple for ages on why they don't sell real servers and why their top of the line is such a joke. I work with After Effects and I also do digital video editing. There's no end to the amount of power you'd like to have at your disposal. Rendering projects to 'see' what you're doing is just time consuming, wasteful and annoying. I know you can do ram previews, etc.. But it REALLY helps to see a full rez version and it often takes many hours to get one.
I am not a tech person so don't quite understand all these details of 32 bit vs 64 bit processors, but it seems to me that the trend of late has been for the hardware to be way out ahead of the software. It wasn't that long ago that running many Photoshop filters meant it was time for a 15 minute coffee break and people were screaming for more horsepower, but nowadays even my "ancient" Powerbook 250mhz G3 runs most in seconds. Of course games and a few other apps like Maya can use all the power they can get, but for most of us it isn't all that necessary. I think this is the biggest reason, other than the slow economy, that computer sales are down. Many people are just not feeling they need more powerful computers, especially in the Wintel world. Mac users of course, no matter what we read about the Mhz myth, still feel we have fallen behind and I think really significantly more powerful Macs like a G5 will sell like hotcakes, even to those who don't really need them, like me.
But I think to really drive hardware sales there needs to be more software that takes makes those machines absolutely NECESSARY...and not software like Maya that costs many thousands of dollars that only big companies can afford. The point I am trying to make here is that while it is great, at least from a marketing standpoint, to go from 32 to 64 bit processors, it may take awhile for new software to appear that really needs 64 bits. Once software developers know they have that many bits to take advantage of they may come up with programs that do things we can't even imagine yet. Basically, what Apple really needs is a "killer app" that only runs on a 64 bit machine and makes their machines a "must have" to the maximum number of people.
Okay, but correct me if I'm wrong here, but this means Darwin can run on all the processors you mentioned, but mac applications and the aqua interface will not run on anything other than a powerpc? Is that right?
Is it possible to bring out an AMD-based Powermac without having to update all your software? (Don't think it is, but just wondering).</strong><hr></blockquote>
Mach and Darwin are already running on the Intel/AMD platform. This means that the entire UNIX layer runs natively on these CPUs. Of course this is not true for Aqua and other OS X frameworks. So MacOS X will NOT run on Intel/AMD, and even recompiling should not work because of the huge differences between PPC and x86.
It would however be possible to use a PPC emulation translating the PPC code into x86 code (like the 68k emulator used in the PMs), today it is even possible to run such an emulation on a very elementar system level or even entirely inside the CPU - think of Transmeta for example. Some weeks ago a company - sorry, forgot the name - demonstrated PPC software (not en entire OS, of course), on an Athlon. Thus the Athlon can emulate a 1 Ghz PowerPC (speaking in terms of G3, I think, and no AltiVec).
But I don't think this would be the right way, an AMD based PowerMac running an emulated OSX would always be slower than the same CPU running a native OS like Win, Linux or any other UNIX.
<strong>...and a new apollo g4, won't that be a considerable speed increase over the current models - like more than some new-fangled 64 bit processor that won't even effect any speed increases?
And if so then why all the focus on the G5? Is it the number? Is it because it can go to eleven? It's one more than a G4?</strong><hr></blockquote>
Be careful now - the fact that 64 bit does not mean a major speed boost does not mean that the G5 is not faster than the G4. 64 bits is only one of many improvements of this architecture, most speed gain is due to the new ALU, the crossbar switch, the new frontside bus, the new memory controller, bigger caches etc. If you look at the G5 specs you can easily imagine that the new design could offer double performance compared to the G4, and the new pipeline/core design allows higher clockrates too - so the G5 should be at least 3 to 5 times faster than the G4 (comparing G5/1.6 to G4/800).
Soon, however, many other users will be running systems, which, between several programmes running simultaneously, will approach that memory requirement.
</strong><hr></blockquote>
It should be noted that running lots of apps is not a reason to require a 64-bit processor! Each application is limited to a 4 gigabyte address space of its own, but the operating system can manage multiple operating systems, and the PPC hardware is setup to address >32 bits worth of physical address space (52-bits worth, I think?). Whether this is brought out to the bus to allow that much RAM to be used, I'm not sure, but the OS could juggle many apps with 4 gigs of virtual memory each.
Regarding the comment about greater performance from the G5 due to non-64bit reasons: absolutely! Have you seen the other thread that purports to have a quote from somebody who has recompiled their app on a G5 and seen a 6-8x performance improvement over an 800 G4x2? [edit: Oh,wait -- that's THIS thread!! Duh.] Whether true or not, whether the machine will arrive in a week or not, it is plausible! Processors are very complex devices and can't be characterized by a couple of simple numbers (i.e. MHz, X-bits, etc) -- there are many many things chip companies can do to make them go much faster. We've been stuck with the G4 for two years now, but one day (soon, I hope) Apple will unveil what comes next and you can bet that it will be a significant step up.
Even if we don't get G5 next week, a >1 GHz Apollo w/ DDR memory, 1394b, and USB2 would be a welcome improvement. They'll need to get more price competitive if that's all it is, however. On the other hand, a G5 machine with a stunning leap in performance could command the traditional Apple pricing margin -- and I'm sure Steve is pushing for it really hard.
There is still one point that confuses me - will Apple use RapidIO or HyperTransport in their future products, or maybe both? I did some research in this area, but as already mentioned, very confusing...
Both Motorola and IBM are supporting RapidIO, and both companies have announced that their future CPU generations (like the G5) will support this bus. You will find nothing about HyperTransport on IBMs or Motorolas website.
On the other hand Apple supports HyperTransport, a bus that AMD wants to use with their future CPUs.
RapidIO and HyperTransport are not compatible, they cannot emulate each other and, as far as I know, there is no RapidIO/HyperTransport bridge (even not announced).
Some people say that RapidIO is the memory bus while HyperTransport is used to connect to PCI, but THAT'S NOT TRUE. As far as I know the 8540 offers a RapidIO bus plus an internal DDR Ram controller and a dedicated memory bus. This means that the memory will NOT be connected to the CPU using RapidIO (which makes much more sense to me).
I took a look at both the RapidIO and HyperTransport specs and to me it seems that RapidIO is much more powerful than HyperTransport. And as I already mentioned, the G5 will probably offer a RapidIO bus. You don't need HyperTransport for PCI or Ethernet either, as there are RapidIO/PCI(X) bridges as well as RapidIO/Ethernet ASICs. So it makes no sense at all to use HyperTransport on a G5 motherboard, doesn't it???
If Apple really wants to commit to Hypertransport this can only mean one of the following:
- Apple will use the G5 with a RapidIO/HyperTransport bridge, which is nonsense
- Apple will use the G5 with a RapidIO motherboard, and HyperTransport is meant for something else (but what?)
- Apple will use a version of the G5 that will not use RapidIO but HyperTransport (this would mean they had to develop this themselves, as IBM and Moto only support RapidIO, sounds very unlikely to me)
Has Apple ever said something about HyperTransport or RapidIO in public? Why does everyone expect a HyperTransport MB if the G5 apparently supports only RapidIO???
<strong>Has Apple ever said something about HyperTransport or RapidIO in public? Why does everyone expect a HyperTransport MB if the G5 apparently supports only RapidIO???
</strong><hr></blockquote>
Good questions. The only thing I know for sure is that Apple is one of the key members of the HyperTransport group. HT seems to be just a point-to-point serial interface between chips on the motherboard, albeit a really fast one. I don't know much about RapidIO, but this quote from their website is illuminating:
"This new high-performance, packet-switched interconnect technology was designed for embedded systems, primarily for the networking and communications markets."
Speculation is fun so I'll indulge a little:
- AMD is the primary force behind HT so if they were designing a G5 for Apple it would be HT.
- Apple's needs are quite different than IBM & Moto (who are obsessed with embedded systems), so perhaps they are doing that part of the G5 themselves? Or the whole design?
- Motorola isn't interested in HT, but if they were doing the G5 just for Apple they might put it in the design on request. They certainly wouldn't jump on the HT bandwagon for anything else they are doing.
- Either of these bus designs is really really fast!!
DaveGee, I don't understand why you were so dismayed by my lack of patience with the creator of this thread, which you yourself have dismissed as incredulous.
Thanks for trying to educate me about the purpose of these boards, but I've been a reader/member or these boards for years, and in case you haven't let me tell you there was a time when these boards provided a lot of real insight into the development of new Mac hardware.
Today, Apple has all but extinguished 'insider' information, and in its place has sprung up a flood of posters who are yanking our chains with vague reports and rehashed rumors. Frankly I'm tired of them and I'm tired of the people who justify them as being 'part of the fun' of these boards. There are lots of other BBS out there that cater to the Mac platform and I hit a lot of them. But the AI forums have always been a place where real information was discussed and debated. Today we joke about the 'I met this guy who works for Apple and he got pretty drunk and started telling me...' posts, but sadly they're becoming the norm.
I'd hate to see these boards de-evolve into something like the MacAddict boards, and I think that if we keep encouraging these absurd posts then that's exactly what will happen.
But that's just my opinion, I suppose. So ultimately I guess I'm curious why, if you're so quick to defend fahre451's right to post are you so interested in condeming mine?
[wow...I like it up on this soapbox...I think I can see my house from here...]
It should be noted that running lots of apps is not a reason to require a 64-bit processor! Each application is limited to a 4 gigabyte address space of its own, but the operating system can manage multiple operating systems, and the PPC hardware is setup to address >32 bits worth of physical address space (52-bits worth, I think?). Whether this is brought out to the bus to allow that much RAM to be used, I'm not sure, but the OS could juggle many apps with 4 gigs of virtual memory each.
</strong><hr></blockquote>
True, having a 64 bit chip does make it easier but it is not necessary. My point was that once people put more than 4GB of RAM in their machines, they're going to want each programme to be able to address it, and also programmers will start finding uses for it. This is not far away in time. I have produced a few pieces of software that at times would have benefitted from more than 32 bit pointers.
The current 7450 I believe has a 36 bit physical address bus.
I have produced a few pieces of software that at times would have benefitted from more than 32 bit pointers.
</strong><hr></blockquote>
Heh, I know what you mean. One of the projects I've got on the back burner is anxiously awaiting a 64-bit machine... I remain hopeful that Apple will pull the rabbit out of the hat in a week and surprise everyone, but I wouldn't put money on it.
I know that NEXTSTEP (before it became Mac OSX) was ported to Sun Solaris SPARC, a 64 bit architecture, so it would make sense that a 64bit G5 would have little problems in porting OSX over to it. And they would reap a lot of benefits in that..
</strong><hr></blockquote>
The NEXTSTEP port never supported the UltraSPARC chip, which was the first 64-bit capable CPU shipped by Sun, so this really has no bearing on reality. The "best" Sun machine supported (shipped from Sun) was the Sun SPARCSTATION 20/71 (that's 71 as in "70MHz and some extra cache memory" IIRC - the code base for OS X have diverged quite a bit in the meantime)
There is also a weird common notion that 64-bit (or should we say more-bit) is inherently good - there is a non-trivial penalty wrt cache/RAM usage when bumping things up in "bitness" - without any real benefit unless you need:
First comes human nature... Don't open that box Johnny... What do you think the first thing little Johnny does..
</strong><hr></blockquote>
"Little Johnny" is not a grown-up working at a real job.
I'm not making any statements about the original poster's veracity, but I am saying that if Apple is going to the trouble of sending out secure hardware prototypes, they would certainly do so under strict agreements with their testers stipulating that the testers will make no effort to open the cases or otherwise ascertain what's inside them. Some idiot cracking open such a unit would not only get himself into trouble, he'd probably keep any developmental hardware out of his company's hands for a good while after.
Would I be tempted to peek inside? Absolutely. Would I actually do it? No.
Comments
<strong>
I'm afraid you are somewhat off base, yes. A simple recompile will give you a working programme, so long as nothing in the programme is dependent on the size of items in memory, especially pointers. Currently all pointers are 32 bits, and a lot of structures used in the OS assume this, so you need glue code to adjust this in a 64 bit environment.
However, I believe that OSX was written with 64 bitness in mind, so most of the work has already been done, but for certain no one will be sure until after they have actually run a large number of existing programmes on 64 bit hardware and software, as with most development of existing code, the vast majority of the time is spent testing.
Michael</strong><hr></blockquote>
Ah, I'd forgotten about pointer math. I guess I've been spending too much time with Java lately. Thanks for explaining that.
Thanks for the lesson in CPU's... It clears up many falsehoods that keep getting spouted about. But, after reading everything you wrote about 32 vs 64bit CPU's... What I'm not sure I understand is WHY?
Why do we need to move to a 64bit system... It seems from what you've written most things will not see any major pop in performance due to the 64bitness of the CPU. The pop will come from other factors such as Mhz etc (as with any new CPU).
So what real world computer tasks could benefit with a computer running 1 64bit over say 2 (or more) 32bit cpus. Unless building the new CPU as a 64bit isn't a 'big deal' and the chip designers are just doing it 'because it doesn't really matter one way or the other'.
I hope that makes some sence...
Dave
[ 12-29-2001: Message edited by: DaveGee ]</p>
PowerPC (dedicated code setpus for 601, 603, 603e, 603ev, 604, 604e, 750 (using different l2 cache configurations), 750cx, 7400 (using different l2 cache configurations), 7410, 7450 (using different l2/l3 cache combinations). Note the support for the 601. Neither the 7460 nor the 8500 are listet in currently available OS X versions. If the 7460 is more than just a 7450 with better fab process (different l2/l3 cache config for example) we should get an updated OS with the new machines. If the 7460 is very similar to the 7450 Apple probably won't add specific code for this CPU, 10.1.2 doesn't add specific 7440 code either (the 7440 is considered to be a 7450 with 0kb l3 cache, as far as I can see).
Intel x86 (dedicated code setups for i386, i486, i486sx, PentiumPro, PentiumII). Note the lack of support for the original Pentium CPU, this processor probably is considered to behave like a 486, no support for MMX. The P6 design has been separated in PPro and PII because of the different L2 configs, PIII and PIV use the same setup as PII. All this is needed for the Intel port of Darwin, for example, it does NOT mean that Apple will ever offer OS X on the x86 architecture. Athlon is considered to be 100% x86 compatible.
Intel Risc aka i860/i960 (i960 is considered to be 100% compatible with i860).
Motorola 68k (68030 and 68040 only). Note that 68000, 68010 and 68020 would not be able to run the OS X base system because of the lack of hardware support, like MMU and more... 68060 is considered to be 100% compatible with 68040.
Motorola 88k Risc (only one code setup for all CPUs)
HPPA / Hewlett Packard Precision Architecture (optimized for the 7100lc)
Sun SPARC (only one code setup for all CPUs)
Note that the system core has been designed to run on little and big endian systems (you will be able to comile it for Intel and other platforms). I can assure you that at least some parts of the core system have been prepared for 64 bit. The entire system core / UNIX layer (which is based partly on NeXTstep, OpenBSD and NetBSD) has been designed for 32 and 64 bit processors.
Anyway, as already mentioned by others it doesn't make sense for Apple to move to 64 bits, as only very few apps will take real advantage of the 64 bit registers, and I think that a powerful SIMD unit (like Altivec) is much more efficient in most cases than a 64 bit ALU.
BUT - if Apple has learned one thing from Intel, people don't care about the real facts. Look at the mhz myth, Intel needs mhz so much that they even reduce the cpus efficiency for the marketing (-> P4). Apple could use the 64 bit mode for marketing, they would be the first to offer a large number of 64 bit systems. They could say "well, we are still at 1.6 ghz (G5) while Intel is at 2 ghz (P4), but we have a 64 bit cpu instead of only 32 bits. Consumers are stupid, and that's why they'll believe it (why else are people buying Wintel machines?). The G5 will probably be faster than the P4, but not because of 64 bits but because of a better design (enhanced ALU, Ocean crossbar witch, RapidIO,...). But Apple can't use these facts for marketing, as the common consumer has never heard of "ALUs", "crossbar switches" or whatever. Remember the Nintendo64? All the hype they made with their 64 bit CPU, that's just the same...
Not having a 64-bit processor, however, means that you are limited in those areas where you really do need one. Apple will go there, its just a matter of when.
And if so then why all the focus on the G5? Is it the number? Is it because it can go to eleven? It's one more than a G4?
(Sorry if I'm mastering the obvious here - I've just been so caught up in the g5 frenzy that I'm starting to think the semantics of the change are more important than the actual change itself.)
Hell, if Apple brings out new powermacs with faster ram and faster buses, and dual processor machines over 1.2 Ghz, I'll take three, thanks very much (for work and home)!!!
<strong>The kernel and base OS design has built-in support for the following processor architectures, even if the machine code for every single cpu might not be included in current compiled versions:</strong><hr></blockquote>
Okay, but correct me if I'm wrong here, but this means Darwin can run on all the processors you mentioned, but mac applications and the aqua interface will not run on anything other than a powerpc? Is that right?
Is it possible to bring out an AMD-based Powermac without having to update all your software? (Don't think it is, but just wondering).
<strong>Programmer,
Thanks for the lesson in CPU's... It clears up many falsehoods that keep getting spouted about. But, after reading everything you wrote about 32 vs 64bit CPU's... What I'm not sure I understand is WHY?
Why do we need to move to a 64bit system... It seems from what you've written most things will not see any major pop in performance due to the 64bitness of the CPU. The pop will come from other factors such as Mhz etc (as with any new CPU).
So what real world computer tasks could benefit with a computer running 1 64bit over say 2 (or more) 32bit cpus. Unless building the new CPU as a 64bit isn't a 'big deal' and the chip designers are just doing it 'because it doesn't really matter one way or the other'.
</strong><hr></blockquote>
The cost of adding 64bitness to a processor is relatively small. Firstly it only affects the integer portions, the FPU and the vector unit already work with as wide or wider data paths, and the extensions of the ALUs to handle 64 bits is relatively simple, there is a bit of overhead for controlling the mode (32 or 64 bits).
The big advantage to 64 bits is not in any internal operations but in being able to logically address more than 4GB of memory. This may not seem like much of a limitation at the moment, but people handling large databases, complex rendering projects, some CAD systems, and a lot of scientific modelling, are already using more than that memory, and using 64 bits makes that a lot easier. Soon, however, many other users will be running systems, which, between several programmes running simultaneously, will approach that memory requirement.
Michael
<strong>
The big advantage to 64 bits is not in any internal operations but in being able to logically address more than 4GB of memory. This may not seem like much of a limitation at the moment, but people handling large databases, complex rendering projects, some CAD systems, and a lot of scientific modelling, are already using more than that memory, and using 64 bits makes that a lot easier. Soon, however, many other users will be running systems, which, between several programmes running simultaneously, will approach that memory requirement.
Michael</strong><hr></blockquote>
BINGO!!!! A HA! Thank you so much for this. Now it makes sense to me why Apple is designing a 64 bit processor.
The image is of an SGI Octane in the middle of a set of Apple-branded crosshairs.
Okay, so that's no big revelation. But I've been writing Apple for ages on why they don't sell real servers and why their top of the line is such a joke. I work with After Effects and I also do digital video editing. There's no end to the amount of power you'd like to have at your disposal. Rendering projects to 'see' what you're doing is just time consuming, wasteful and annoying. I know you can do ram previews, etc.. But it REALLY helps to see a full rez version and it often takes many hours to get one.
Thanks!
But I think to really drive hardware sales there needs to be more software that takes makes those machines absolutely NECESSARY...and not software like Maya that costs many thousands of dollars that only big companies can afford. The point I am trying to make here is that while it is great, at least from a marketing standpoint, to go from 32 to 64 bit processors, it may take awhile for new software to appear that really needs 64 bits. Once software developers know they have that many bits to take advantage of they may come up with programs that do things we can't even imagine yet. Basically, what Apple really needs is a "killer app" that only runs on a 64 bit machine and makes their machines a "must have" to the maximum number of people.
<strong>
Okay, but correct me if I'm wrong here, but this means Darwin can run on all the processors you mentioned, but mac applications and the aqua interface will not run on anything other than a powerpc? Is that right?
Is it possible to bring out an AMD-based Powermac without having to update all your software? (Don't think it is, but just wondering).</strong><hr></blockquote>
Mach and Darwin are already running on the Intel/AMD platform. This means that the entire UNIX layer runs natively on these CPUs. Of course this is not true for Aqua and other OS X frameworks. So MacOS X will NOT run on Intel/AMD, and even recompiling should not work because of the huge differences between PPC and x86.
It would however be possible to use a PPC emulation translating the PPC code into x86 code (like the 68k emulator used in the PMs), today it is even possible to run such an emulation on a very elementar system level or even entirely inside the CPU - think of Transmeta for example. Some weeks ago a company - sorry, forgot the name - demonstrated PPC software (not en entire OS, of course), on an Athlon. Thus the Athlon can emulate a 1 Ghz PowerPC (speaking in terms of G3, I think, and no AltiVec).
But I don't think this would be the right way, an AMD based PowerMac running an emulated OSX would always be slower than the same CPU running a native OS like Win, Linux or any other UNIX.
<strong>...and a new apollo g4, won't that be a considerable speed increase over the current models - like more than some new-fangled 64 bit processor that won't even effect any speed increases?
And if so then why all the focus on the G5? Is it the number? Is it because it can go to eleven? It's one more than a G4?</strong><hr></blockquote>
Be careful now - the fact that 64 bit does not mean a major speed boost does not mean that the G5 is not faster than the G4. 64 bits is only one of many improvements of this architecture, most speed gain is due to the new ALU, the crossbar switch, the new frontside bus, the new memory controller, bigger caches etc. If you look at the G5 specs you can easily imagine that the new design could offer double performance compared to the G4, and the new pipeline/core design allows higher clockrates too - so the G5 should be at least 3 to 5 times faster than the G4 (comparing G5/1.6 to G4/800).
<strong>
Soon, however, many other users will be running systems, which, between several programmes running simultaneously, will approach that memory requirement.
</strong><hr></blockquote>
It should be noted that running lots of apps is not a reason to require a 64-bit processor! Each application is limited to a 4 gigabyte address space of its own, but the operating system can manage multiple operating systems, and the PPC hardware is setup to address >32 bits worth of physical address space (52-bits worth, I think?). Whether this is brought out to the bus to allow that much RAM to be used, I'm not sure, but the OS could juggle many apps with 4 gigs of virtual memory each.
Regarding the comment about greater performance from the G5 due to non-64bit reasons: absolutely! Have you seen the other thread that purports to have a quote from somebody who has recompiled their app on a G5 and seen a 6-8x performance improvement over an 800 G4x2? [edit: Oh,wait -- that's THIS thread!! Duh.] Whether true or not, whether the machine will arrive in a week or not, it is plausible! Processors are very complex devices and can't be characterized by a couple of simple numbers (i.e. MHz, X-bits, etc) -- there are many many things chip companies can do to make them go much faster. We've been stuck with the G4 for two years now, but one day (soon, I hope) Apple will unveil what comes next and you can bet that it will be a significant step up.
Even if we don't get G5 next week, a >1 GHz Apollo w/ DDR memory, 1394b, and USB2 would be a welcome improvement. They'll need to get more price competitive if that's all it is, however. On the other hand, a G5 machine with a stunning leap in performance could command the traditional Apple pricing margin -- and I'm sure Steve is pushing for it really hard.
[ 12-29-2001: Message edited by: Programmer ]</p>
Both Motorola and IBM are supporting RapidIO, and both companies have announced that their future CPU generations (like the G5) will support this bus. You will find nothing about HyperTransport on IBMs or Motorolas website.
On the other hand Apple supports HyperTransport, a bus that AMD wants to use with their future CPUs.
RapidIO and HyperTransport are not compatible, they cannot emulate each other and, as far as I know, there is no RapidIO/HyperTransport bridge (even not announced).
Some people say that RapidIO is the memory bus while HyperTransport is used to connect to PCI, but THAT'S NOT TRUE. As far as I know the 8540 offers a RapidIO bus plus an internal DDR Ram controller and a dedicated memory bus. This means that the memory will NOT be connected to the CPU using RapidIO (which makes much more sense to me).
I took a look at both the RapidIO and HyperTransport specs and to me it seems that RapidIO is much more powerful than HyperTransport. And as I already mentioned, the G5 will probably offer a RapidIO bus. You don't need HyperTransport for PCI or Ethernet either, as there are RapidIO/PCI(X) bridges as well as RapidIO/Ethernet ASICs. So it makes no sense at all to use HyperTransport on a G5 motherboard, doesn't it???
If Apple really wants to commit to Hypertransport this can only mean one of the following:
- Apple will use the G5 with a RapidIO/HyperTransport bridge, which is nonsense
- Apple will use the G5 with a RapidIO motherboard, and HyperTransport is meant for something else (but what?)
- Apple will use a version of the G5 that will not use RapidIO but HyperTransport (this would mean they had to develop this themselves, as IBM and Moto only support RapidIO, sounds very unlikely to me)
Has Apple ever said something about HyperTransport or RapidIO in public? Why does everyone expect a HyperTransport MB if the G5 apparently supports only RapidIO???
[ 12-29-2001: Message edited by: macrumorzz ]</p>
<strong>Has Apple ever said something about HyperTransport or RapidIO in public? Why does everyone expect a HyperTransport MB if the G5 apparently supports only RapidIO???
</strong><hr></blockquote>
Good questions. The only thing I know for sure is that Apple is one of the key members of the HyperTransport group. HT seems to be just a point-to-point serial interface between chips on the motherboard, albeit a really fast one. I don't know much about RapidIO, but this quote from their website is illuminating:
"This new high-performance, packet-switched interconnect technology was designed for embedded systems, primarily for the networking and communications markets."
Speculation is fun so I'll indulge a little:
- AMD is the primary force behind HT so if they were designing a G5 for Apple it would be HT.
- Apple's needs are quite different than IBM & Moto (who are obsessed with embedded systems), so perhaps they are doing that part of the G5 themselves? Or the whole design?
- Motorola isn't interested in HT, but if they were doing the G5 just for Apple they might put it in the design on request. They certainly wouldn't jump on the HT bandwagon for anything else they are doing.
- Either of these bus designs is really really fast!!
[ 12-29-2001: Message edited by: Programmer ]</p>
Thanks for trying to educate me about the purpose of these boards, but I've been a reader/member or these boards for years, and in case you haven't let me tell you there was a time when these boards provided a lot of real insight into the development of new Mac hardware.
Today, Apple has all but extinguished 'insider' information, and in its place has sprung up a flood of posters who are yanking our chains with vague reports and rehashed rumors. Frankly I'm tired of them and I'm tired of the people who justify them as being 'part of the fun' of these boards. There are lots of other BBS out there that cater to the Mac platform and I hit a lot of them. But the AI forums have always been a place where real information was discussed and debated. Today we joke about the 'I met this guy who works for Apple and he got pretty drunk and started telling me...' posts, but sadly they're becoming the norm.
I'd hate to see these boards de-evolve into something like the MacAddict boards, and I think that if we keep encouraging these absurd posts then that's exactly what will happen.
But that's just my opinion, I suppose. So ultimately I guess I'm curious why, if you're so quick to defend fahre451's right to post are you so interested in condeming mine?
[wow...I like it up on this soapbox...I think I can see my house from here...]
<strong>
It should be noted that running lots of apps is not a reason to require a 64-bit processor! Each application is limited to a 4 gigabyte address space of its own, but the operating system can manage multiple operating systems, and the PPC hardware is setup to address >32 bits worth of physical address space (52-bits worth, I think?). Whether this is brought out to the bus to allow that much RAM to be used, I'm not sure, but the OS could juggle many apps with 4 gigs of virtual memory each.
</strong><hr></blockquote>
True, having a 64 bit chip does make it easier but it is not necessary. My point was that once people put more than 4GB of RAM in their machines, they're going to want each programme to be able to address it, and also programmers will start finding uses for it. This is not far away in time. I have produced a few pieces of software that at times would have benefitted from more than 32 bit pointers.
The current 7450 I believe has a 36 bit physical address bus.
Michael
<strong>
I have produced a few pieces of software that at times would have benefitted from more than 32 bit pointers.
</strong><hr></blockquote>
Heh, I know what you mean.
[ 12-29-2001: Message edited by: Programmer ]</p>
<strong>
I know that NEXTSTEP (before it became Mac OSX) was ported to Sun Solaris SPARC, a 64 bit architecture, so it would make sense that a 64bit G5 would have little problems in porting OSX over to it. And they would reap a lot of benefits in that..
</strong><hr></blockquote>
The NEXTSTEP port never supported the UltraSPARC chip, which was the first 64-bit capable CPU shipped by Sun, so this really has no bearing on reality. The "best" Sun machine supported (shipped from Sun) was the Sun SPARCSTATION 20/71 (that's 71 as in "70MHz and some extra cache memory" IIRC - the code base for OS X have diverged quite a bit in the meantime)
There is also a weird common notion that 64-bit (or should we say more-bit) is inherently good - there is a non-trivial penalty wrt cache/RAM usage when bumping things up in "bitness" - without any real benefit unless you need:
a) The increased address space
b) The increased address space
c) The increased address space
d) support for "large" integers
Oh well.
<strong>
This one line tells me this whole post is BS...
First comes human nature... Don't open that box Johnny... What do you think the first thing little Johnny does..
</strong><hr></blockquote>
"Little Johnny" is not a grown-up working at a real job.
I'm not making any statements about the original poster's veracity, but I am saying that if Apple is going to the trouble of sending out secure hardware prototypes, they would certainly do so under strict agreements with their testers stipulating that the testers will make no effort to open the cases or otherwise ascertain what's inside them. Some idiot cracking open such a unit would not only get himself into trouble, he'd probably keep any developmental hardware out of his company's hands for a good while after.
Would I be tempted to peek inside? Absolutely. Would I actually do it? No.
<strong>
Read the bold. Now, let the bold text sink in. This is nothing more than some Mac fan's online diary. He's quoting MOSR in his diary.
Wow.
Amazing.
Holy fscking sh*t!
I can hardly contain my joy.</strong><hr></blockquote>