Mojave
Some, or maybe many, speculate that the IBM Mojave 'G3' will actually be a replacement for the current Motorola G4. With the IBM 970 being used in the highest performance Macs, Apple needs a lower cost, lower power CPU for lower end Macs, like the iBook, eMac and whatever else Apple does at the low end.
Possibly this low end CPU can be simpler than the present G4. For example, it might be argued that it does not need to be SMP capable. On the other hand, maybe even a low end CPU could benefit from some features of the 970 without adding much to its cost or power.
So my question is this: What features should be added to a G3 to enhance its performance, without adding too much in the way of cost or power dissipation? AltiVec is almost a certainty for all future Macs, but can it be simpler than the 970 version? What about the 970 style bus? What about FPU? What about length of the pipe line? What about other special features in the 970? Is any of this useful at the really low end of the Mac product line?
I would be very interested in reading what others think about the future low end CPU. I'd like to get my mind off the imminent 970 Power Macs for a while, and read comments on more distant events. I look forward to learning something, but I don't know enough to contribute much to the topic.
Possibly this low end CPU can be simpler than the present G4. For example, it might be argued that it does not need to be SMP capable. On the other hand, maybe even a low end CPU could benefit from some features of the 970 without adding much to its cost or power.
So my question is this: What features should be added to a G3 to enhance its performance, without adding too much in the way of cost or power dissipation? AltiVec is almost a certainty for all future Macs, but can it be simpler than the 970 version? What about the 970 style bus? What about FPU? What about length of the pipe line? What about other special features in the 970? Is any of this useful at the really low end of the Mac product line?
I would be very interested in reading what others think about the future low end CPU. I'd like to get my mind off the imminent 970 Power Macs for a while, and read comments on more distant events. I look forward to learning something, but I don't know enough to contribute much to the topic.
Comments
1. Altivec
2. System bus that scales in proportion to CPU clockspeed, ala PPC 970
3. MHz
4. Low power (already has it, but should still be a high priority for laptops and funky hardware designs).
Then Jobs can tell Motorola what's REALLY on his mind...if he hasn't already.
Originally posted by snoopy
So my question is this: What features should be added to a G3 to enhance its performance, without adding too much in the way of cost or power dissipation? AltiVec is almost a certainty for all future Macs, but can it be simpler than the 970 version? What about the 970 style bus? What about FPU? What about length of the pipe line? What about other special features in the 970? Is any of this useful at the really low end of the Mac product line?
It's fairly obvious, but with the 970, it won't be that useful.
1. Add an AltiVec unit.
2. Increase the execution pipeline to 10 stages.
3. Add the PPC 970 bus.
4. Add power management features (like seen in Pentium-M).
5. Make it 3 dispatch/complete + 1 branch wide.
Or IBM can just add power manegement features in the PPC 970, and Apple can forget about using Mojave on any of its computers. The only usefulness of a Mojave class CPU for Apple, if the PPC 970 is as good as it appears, is in low end sub-$1000 machines or special portables (tablet et al).
better FPU
support for DDR
my humble thoughts... i can't wait for apple to be done with Motorola.
na
2) Put the memory controller on board, and use RapidIO as a bus. The memory controller adds very little to the die size and obviates the need for a companion chip (which the 970 requires). RapidIO is designed to be cheap to implement, it scales very well, and it would be an unambiguous improvement over the current G3's 60x bus and the G4's MaxBus. This also happens to be the direction the embedded market's going, so Apple could benefit from jumping on that bandwagon.
Power management features are almost redundant in a chip this small, (assuming that it's fabbed at 90nm) but being able to alter the clock speed at run time and shut down unused parts of the CPU might help. I'd be surprised if the current G3 doesn't have some sort of power management - simple, no doubt, but then it doesn't need anything elaborate.
Really, that's it. Then you have a decent performer with a small footprint that sips a small amount of power and doesn't cost much. Add a second FPU (not that much more silicon, really), and it would even be able to acquit itself at more "pro" applications.
g
Originally posted by thegelding
i think gobi is next (soon) but without altivec...then they add altivec to gobi and it becomes mojave...that is the simplified version of what i understand...of course programmer or amorph will drop by and correct me
Its all just rumours so "contradicting you" is probably more accurate than "correcting you". If you're talking about the Naked Mole Rat rumour from a while back, I believe that he said that Mojave would be a substantially different core with significantly lower power consumption and improved power management (relative to the existing G3). It wasn't entirely clear if VMX (AltiVec) would show up in Gobi or Mojave. RapidIO & on-chip memory controller might be in there too.
Good news for the iBook when they arrive.
so prog...will gobi have altivec or will that come with mojave??
g
Originally posted by thegelding
told you programmer would show up to kick my ass....
so prog...will gobi have altivec or will that come with mojave??
g
I have no idea, I was just regurgitating when I remember from reading NMR.
Originally posted by Bodhi
Increase the pipeline? Why? IBM is doing just fine scaling the G3 up without changing the pipeline. The only reason we only have a 900MHz G3 is because of Apple, not IBM. I would much rather have a short pipeline 1.2GHz G3 than a long pipeline one.
IBM has already change the pipeline of the G3 from 4 to 5 stage in the lattest version the 750 fx.
Some years ago, IBM have announced the sahara 2. Is the sahara 2 the PPC 970 or is it an evolution of the the 750 fx (code name sahara) ?
Mustibore Superscalar
SMP capable
Integrated SIMD engine
Rapid I/O
n-way Crossbar CoreConnect
These spec's suit me just fine. My question is if Apple wants a unified motherboard architecture, wouldn't Rapid I/O require some different features in the controller chip than used with an IBM 970? And wouldn't this tend to up costs having to use different motherboard architectures?
Whether all of this is to be believed of course is why we are here.
but it is all just guess work....how hard is it to just jam a altivec chip onto a board?? if gobi is coming w/o altivec and apple sez, please, could ibm just have a bunch of cleaning people stay late and jam them on with their thumbs??
g
Seeing that is the way Apple will go however, I don't think the G3 moniker would stay. A lot of people would feel they are downgrading, even with altivec. So maybe that's the answer to Apple's future naming scheme, no more Gx, so Maybe Powermac 970 and the iMac featuring a 1.4ghz Mojave? Or whatever model # it is, I just don't see the 'G3' title staying but I do the chip.
Originally posted by KidRed
I think it's painfully obvious that the iMac, iBook and eMac will be getting these chips....
If you mean the iMac would be updated to a cpu w/out Altivec/Velocity Engine/VMX, I doubt that. Maybe the iBook and/or eMac, but not the iMac. I think going to a cpu w/out SIMD could very well be the death of that line. But then again in the immortal words of Rosanne Rosanna Danna,"you just never know Mr. Fader".
Originally posted by KidRed
. . . Seeing that is the way Apple will go however, I don't think the G3 moniker would stay. A lot of people would feel they are downgrading, even with altivec. . .
If the Mojave has AltiVec, it will not be called a G3 for another reason -- confusion about system requirements for those buying software. There is a lot of software out there with G3 and G4 mentioned on the box.
Originally posted by snoopy
Two things mentioned are encouraging for reducing component cost on Apple's low end Macs. One is a possible built-in memory controller, which would eliminate an external chip.
Not necessarily. Apple integrates the memory controller into another ASIC currently, so it would actually just move the problem around. I'm not sure how Apple would implement their robust DMA (direct memory access, so that hard drives, optical drives, external devices, PCI and AGP cards can read and write directly to RAM without bugging the CPU with every request or clogging its bus with their data) on a Gobi board. Maybe they're just not concerned with that level of performance on Gobi-class hardware? I honestly don't know.
However, there are design and performance advantages to having the memory controller be part of the CPU, and Apple has one less component to engineer themselves.
Furthermore, if the 970's companion chip has a memory controller and a RapidIO interface to the rest of the board, then Apple can make all their chips talk over RapidIO exclusively, and add a Gobi or Mojave or 970 + companion chip to the fabric as needed.
Maybe it's the presence of the name CoreConnect, but I can't help wondering when Cell will start arriving (soon!) and if, or how, Apple will leverage it in their own products. One G3 is a fairly humble little chip, but if you throw enough G3s at a problem, the performance of the individual core doesn't matter so much. At 10 watts a pop, max, that's not hard to do economically...
Originally posted by Amorph
...but I can't help wondering when Cell will start arriving (soon!) and if, or how, Apple will leverage it in their own products.
I think the last I heard was late 2004 for the Cell "supercomputer on a chip" for the Gamecube. But who knows.