Design Philosophy of the IBM PowerPC 970 232
D.J. Hodge writes "Ars Technica has a very detailed article on the PowerPC 970 up that places the CPU in relation to other desktop CPU offerings, including the G4 and the P4. I think this gets at what IBM is doing: 'If the P4 takes a narrow and deep approach to performance and the G4e takes a wide and shallow approach, the 970's approach could be characterized as wide and deep. In other words, the 970 wants to have it both ways: an extremely wide execution core and a 16-stage (integer) pipeline that, while not as deep as the P4's, is nonetheless built for speed.'"
Every time I readone of these articles... (Score:4, Insightful)
Kudos to the Ars team yet again for going deeper into CPU designs than 99% of the populace need to go :)
PPC, not just for Apple any more (Score:5, Insightful)
This chip could be the start of something big in the Linux space as well. Think about it, we are now at a point where a few companies other than Intel are now poised to take the center stage in the next gen workstation, most notably AMD, Apple, and now IBM themselves.
While Linux has run on PPC chips for a long time, it is difficult to come upon a G4 chip without paying the "Apple Tax" for the hardware. If IBM steps up to the plate with this chip, which can then run OS X, Mach, Linux, *BSD, (insert other OS'es here), and can be purchased directly or in a package from IBM, we may see a good set of Windows challengers for the desktop and server room. Obviously OS X will still only run on Apple derivatives.
These chips will be big, I guarantee it, and not just for Apple. It will be interesting to see if Microsoft ports Win XP to these chips.
Re:They should make it work three ways (Score:5, Insightful)
Intel and AMD have the x86 market pretty well locked down.
More importantly, why would ANYBODY want to implement the x86 ISA (Instruction Set Architecture or smtn like that). It's the most horrid instruction set in use today.
Some instruction sets can't really be mapped to others easily, and optimizing for good performance with PPC would probably not have good x86 performance anyways.
In Pentiums and Athlons, the instruction set isn't really emulated. It's translated to a smaller instruction set (uops, iops, pick whatever term you like and run with it). However, these smaller sets are still made pretty much specifically to cover the overlying ISA (x86 in this case).
Re:unfotunatly Apple is going with Intel instead.. (Score:5, Insightful)
I think Apple will stick with a company that it knows, IBM, since they have been working together for years. It doesn't seem that Apple will just jump ship to the x86 platform. This would also mean redoing the Mac OS X code and optimization (not like they will have to do some anyway, but they will have to do more). It is highly unlike that Apple will go with a heat producing, energy wasting x86 Intel chip.
Re:unfotunatly Apple is going with Intel instead.. (Score:5, Insightful)
wide / transistors (Score:5, Insightful)
it operates very much like itanium, w.r.t to group bundling / dispatch of IOPs. Very much like itaniums 3-bundle EPIC codes, but itanium requires the compiler to best pack the templates, whereas the 970 builds each bundle based on dependencies. funny how they both punt with nops.
i wouldn't be surprised if it has similar int performance as itanium, but better fp. i would expect integer to be better on p4 by the time the 970 hits the streets in systems. intel keeps increasing the number of int execution ports.
although, i wouldn't call it wide-and-deep -- it has distinct vector and FP units, but they are rarely used simulataneously, so i suspect they will be idle most of the time. there's only 2 integer units compared to p4's 4.5. so if most of the time the execution engines are idle, it isn't really 'wide'.
goes to show how bulky x86 decode is -- 970 has fewer transistors, but the same cache size, more branch resources, and more Vector/FP hardware than p4!!
now watch the bias on
They wouldn't have to redo anything... (Score:2, Insightful)
Are they going to jump ship to x86? Not likely if they can help it... but they're keeping the option open. Kind of like how Dr. Evil KNOWS his plans will never fail, but he always has that Big Boy rocket hidden in the back--just in case.
And who ya calling energy wasting? My Palomino keeps my room nice and toasty on those lonely nights and makes great julienne fries!
Re:unfotunatly Apple is going with Intel instead.. (Score:4, Insightful)
Re:unfotunatly Apple is going with Intel instead.. (Score:0, Insightful)
Re:$$$/performance (Score:1, Insightful)
Tom
Re:unfotunatly Apple is going with Intel instead.. (Score:2, Insightful)
P.S. My 333Mhz P2 runs great at 400Mhz, but largely because Intel underclocked the identical core to run at 333Mhz. Intel plays up the importance of clock speed, so they do dumb things like underclocking, and multiplyer locking.
For those /.ers who will not read the article (Score:5, Insightful)
For those not planning to read the article, I wanted to mention the following so you do not get the wrong impression. The speed that the article refers to (of a long integer pipeline, like a 16-stage or like the Pentium IV's 20-stage) is clockspeed, not necessarily actual performance. The P4's super long pipeline, for example, allows it to run at higher clock speeds, but less work gets done in the same number of clock cycles. This is the "braniac" vs "speed demon" philosophy (with a high clock speed but low instructions-per-clock representing "speed demon") and neither is necessarily better than the other (though one is obviously better for the marketing dept.)
Just don't assume that "built for speed" always means "built to be fast" -- a confusing but important distinction.
Decoded cache in the P4. (Score:3, Insightful)
The P4 has its flaws, but IMO cacheing decoded instructions isn't one of them. It shortens the pipeline, and paves the way for a true trace cache (cache of decoded basic blocks indexed by entry point; very handy for renaming and scheduling).
Re:PPC, not just for Apple any more (Score:3, Insightful)
Bear in mind that when IBM says "desktop workstation" they mean a $20k+ machine. Consumer desktop machines these aren't.
Blah blah blah... (Score:2, Insightful)
And now that you mention it, I do remember reading that the M68k was 32-bit, but it only had a 24-bit address bus, which meant the max. amount of RAM it could physically have was 16 megabytes. Again, I'm not trying to bash anybody, I'm trying to point out that your "64-bit CPUs aren't really 64-bit because they only have a 48-bit address bus" argument is flawed.
Why you went off on the whole Apple vs. Wintel thing is beyond me, but if you want to play ball, OK. For the record, the PC wasn't meant to compete with the Lisa or the Mac, and both of those computers were introduced after the PC. The original IBM PC was a competitor to the Apple II, but more oriented towards business use rather than home use. If you remember, the Apple II also used a cassette tape drive (just like the original PC), but, like the PC's successors, the PC-XT and the PC-AT (all modern PCs are descended from the PC-AT), later had the ability to use floppy drives and hard drives.
The 1982 lisa had windows, scolling, dialogs, fonts, buttons, WYSIWYG text editing with graphics, etc.
Which were all "borrowed" from Xerox PARC. The fact that Apple later whined and bitched about Microsoft "borrowing" those ideas from the Lisa and/or Mac (when Apple themselves had stolen those concepts from somebody else in the first place) is too amusing for words. I can't stomach Bill Gates, but I have just as hard of a time putting up with Steve Jobs ("You stole Windows! It's not fair! We stole it first!").
And as for Mac OS always being 8 years ahead of Windows, well, I'm no lover of Windows, but Windows had preemptive multitasking years before Mac OS (Windows got it in Win95, Mac OS didn't have it until OS X).
the Apple II had 75% of us market
Although I don't have any hard facts, I have a hard time with this. It wasn't like IBM and Apple were the only players in the personal computer market. There was Commodore with their highly successful Commodore 64 computer (not to mention the Commodore PET, VIC-20, and Commodore 128), Sinclair, the TRS-80 (from Tandy and RadioShack IIRC), and a whole host of others.
Re:Blah blah blah... (Score:2, Insightful)
Windows NT/2000XP had real pre-emptive multitasking before the half bit crappy win95 implementation. 1993? Think NT 3.1 and Nt 3.51. Those OS's, much maligned then are now the foundation for MS future OS's...