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Yet Another G5 Roundup

Lawrence Person writes "This article on Low End Mac talks about why the PowerPC 970 is so fast, covering its superiority to Intel chips in Multiply Accumulate, double precision arithmetic, and Fast Fourier Transforms, among other operations. A short, clear article for those who don't have the time to wade through Parts 1 and 2 of Ars Technica's exceptionally detailed dissection of the 970/G5." Trollaxor writes "IBM has a neat two-page history of the PowerPC architecture, detailing its evolution from the first RS/6000 chipsets in 1990, through the POWER ISA, and into the processors that we know and use today. A very interesting read."

69 comments

  1. LOL by Anonymous Coward · · Score: 0, Troll

    More facts the Wintel trolls are going to try to dispute.

    Losers.

  2. FFT is a good mesure by Baikala · · Score: 5, Informative

    Fast Fourier Transform is bread and butter for the scientific comunity. This is a good news for sys admins at research centers like me.
    Maybe I have a chance at getting one or two of these babies for the next year budget.

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    16,777,216 comments ought to be enough for any forum!
    1. Re:FFT is a good mesure by torpor · · Score: 2, Interesting

      It need no be said that this is good for my industry too.

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      ; -- the corruption of government starts with its secrets. a truly free people keep no secrets. --
    2. Re:FFT is a good mesure by switcha · · Score: 2, Funny
      Fast Fourier Transform is bread and butter for the scientific comunity. This is a good news for sys admins at research centers like me.

      And for me! I am soooo gonna kick some ass in 'Data Units Completed'.

      --
      You know what? ... A little club soda *did* get that out!
  3. Win AMD by Anonymous Coward · · Score: 0

    My machine runs Windows, but it is an AMD. No Wintel troll I: only some PCs are Wintel (others have Linux or AMD)

  4. Re:This is really cool by fputs(shit,+slashdot · · Score: 0, Flamebait

    I know a couple of women with imacs, chosen because they matched the carpet or something. Those cosmetics cost money, fortunately I have better things to do than stare at in-animate objects. Nothing wrong with the G5 though, if they can knock-out an OS-free dual cpu 1u rack for a reasonable price then I'll buy a few. I'm not paying more for a pretty box tho.

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    I am the bastard of base minus 12! Turing was the ejaculate of my complete machine!
  5. Okay by Japer+Lamar+Crabb · · Score: 5, Insightful

    I understand the excitement over these machines, so I won't get all pissy about this, but...

    Until these machines are widely available, each and every thread concerning the performance of the PPC 970 will run the risk of degenerating into a heated debate over whether the figures being offered are reliable. In other words, a flamefest.

    Don't we already have enough of those around here?

    --
    Habit is the ballast that chains the dog to his vomit - Samuel Beckett, "Proust"
    1. Re:Okay by Johnny+Mnemonic · · Score: 4, Insightful


      Hey, I'm a Mac fan, and I totally agree--while this bodes well for the future, the benefits of the G5 are clearly application specific. So until you'll be able to test it yourself, with the apps that you use, compiled with whatever they're compiled with, it's just another flamefest.

      That said--both you and I clicked the link to "Read More", didn't we?

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      $tar -xvf .sig.tar
  6. Yea, but does it run Linux? by Znonymous+Coward · · Score: 5, Interesting

    Seriously. The G5 PowerMac has like 9 fans in it that are controlled by the OS (Mac OS X). It will be easy to run Linux on it, but will Linux properly control the fans to keep the system from burning up or flying off the desk?

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    Karma: The shiznight, mostly because I am the Drizzle.

    1. Re:Yea, but does it run Linux? by dhovis · · Score: 4, Informative

      I think the tech documents say that if the OS does not provide thermal management, the fans will run at full speed. So it will be interesting to see if the thermal management will be provided under Linux.

      Terrasoft (makers of Yellow Dog Linux) has said that they will support Linux on the G5, but it remains to be seen if they will be able to provide thermal management that won't void the warrenty. Terrasoft is an offical Apple Value Added Reseller, and they sell dual boot MacOS X/Linux systems that carry the full Apple warranty, so Apple may provide them with the info they need or else a binary driver that they can use.

      It may also be that Apple will make the thermal management code open source as part of Darwin. If that is the case, then it can probably be converted into a kernel module without violating either the GPL or APSL.

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      --
      The internet is the greatest source of biased information in the history of mankind.

    2. Re:Yea, but does it run Linux? by Duke+Thomas · · Score: 4, Interesting

      I never thought of that. Why did Apple put the OS itself in charge of regulating the temperature? Why couldn't the fans be controlled by some simple thermostat like mechanism quite apart from the operating system? Apple has been big on software controlling hardware for a while now, but this seems a bit much.

    3. Re:Yea, but does it run Linux? by squiggleslash · · Score: 3, Funny
      There are two things (yeah, just two) I'm not 100% happy about on the G5 series:
      1. The relative lack of expandability (there are only two drive bays, for example, and both are already in used by default - one HD, one optical media)
      2. NINE FANS! Holy crap Apple, what the HELL were you thinking?! I mean, nine fans. That's NINE moving parts. And if any of them fail, presumably that's the end of a $3,000 computer. NINE OF THEM. Geez. Good grief. I've used PCs now for decades, have Amigas and Sinclair QLs and, goddamnit, Dragon 32s still in working order, but I don't have a SINGLE fricking machine that relies upon a fan working that's more than three years old. Why? Because fans fail. And when they fail, woooooooooo the results SUCK more than the fans did.
      Sorry, I just needed to get that off my ch... NINE FANS. Holy crap. Holy, holy crap. Jonathan Ives, what in hell's NAME got into you? I mean, NINE...

      Here's hoping it's not actually nine for optimal airflow, as claimed, but nine for redundancy...

      NINE. Holy crap.

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      You are not alone. This is not normal. None of this is normal.
    4. Re:Yea, but does it run Linux? by Steveftoth · · Score: 2, Insightful

      The design is really to minimize noise I think because if you have lots of slow moving fans, it's a lot quieter then one or two fast moving ones.

      Computers put out too much heat to use passive cooling anymore, the old computers of yore didn't use fans, but people today don't want slow machines so we have to use active cooling.

    5. Re:Yea, but does it run Linux? by Lars+T. · · Score: 1

      Brrrruuurrrp! One of the two Serial ATA drive bays is taken by the HD, the other is free. The optical is in an extra bay.

      --

      Lars T.

      To the guy who modded me down from perfect to terrible Karma - Apple haters still suck

    6. Re:Yea, but does it run Linux? by gerbache · · Score: 2, Interesting

      If a fan fails, it's not necessarily going to kill the computer. Considering Apple says they used 9 fans to reduce noise, something tells me that the failure of a fan will not be a catastrophic failure in terms of the entire system. If the OS is controlling the speed of the fans, then the OS should be able to be written to either limit speeds or shut down the system upon the failure of a fan, so it shouldn't be a real issue. I really don't see why so many people are all hung up on the fact that it uses 9 fans..that's not too many more than my PC desktop uses if you count all of 'em.

    7. Re:Yea, but does it run Linux? by MrTangent · · Score: 5, Interesting

      There are actually two hard drive bays. Look closely.

      The lack of more than two hard drive bays was a concern of mine as well, but the drive that ships with the G5's is 60 to 250 gigabyte Serial ATA. Factor in the plethora of fast Firewire/Firewire 800 external drives and most Mac users will be as happy as pigs in shit (as well as Fibre channel XServe Raid for multi-terabyte storage for the higher end users). So you can get half a terabyte internal Serial ATA in the G5's if you chose to pay the premium. I think that's more than enough for 99% of the population.

      I do agree there's some aspects of the G5 design that seem like a step backwards over the previous G3 & G4 'El Capitan' case. While two hard drive spaces is fine for most users, the G4 allowed you to have four internal hard drives. The lack of a second optical drive bay is also a "step backwards" over the G4 design (this can be rectified with an external Firewire drive if needed, and again, most users don't require a second optical drive).

      For me though the biggest gripe I have with the G5 case is the removal of the drop-down motherboard door design on the G3 (Blue and White) and G4. The one button access with drop-down door was an amazing feat of engineering and it saddens me to see this go. The new G5's internals are very elegant but installing and upgrading RAM, PCI and AGP cards is so much easier on the previous G4 and G3 models (although the G5 certainly looks easier to upgrade/get into than most PC boxes I've worked on before).

      As far as the fans go, I have no gripe there. While it might be more moving parts, the idea of thermal zones is a sound idea and will help keep the machine cool and output less decibels. By the way, the fans will be replaceable. You make it sound like the machine will be junk just because one fan fails. I'm sure Apple has thought of this and will provide replacement fans.

      One could also argue that by having nine fans that work in tandem you'll have less chance for failure since no one fan will be running at 100% at all times like on other machines. This quote kind of explains what I mean:

      "the candle that burns twice as bright burns half as long."

    8. Re:Yea, but does it run Linux? by squiggleslash · · Score: 0
      Ok, it sounds like my concerns about underupgradability (?) are overstated. That's good to hear.

      The issue I have with fans isn't that you wont be able to replace them, but that I know the damage a failed fan can do, especially if it isn't picked up upon quickly enough. Friends who leave their machines on 24/7 have come home to machines that needed replacement CPUs because of fan failures.

      Of course, one hopes that the fan system will work more like those found in modern server type units where the systems automatically shut down when the fans fail. Maybe Apple can restore the "Glass breaking" sound effect for precisely this situation ;-) Though the suggestion that the fans are under software control doesn't exactly make me feel confident that this is what they've done.

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      You are not alone. This is not normal. None of this is normal.
    9. Re:Yea, but does it run Linux? by pmz · · Score: 2, Interesting

      I've used PCs now for decades, have Amigas and Sinclair QLs and, goddamnit, Dragon 32s still in working order, but I don't have a SINGLE fricking machine that relies upon a fan working that's more than three years old.

      For PCs, this may be true, but for better hardware, such as (hopefully) the PowerMac G5, the fans should last at least five years, not three. This has been my experience with Sun workstations, where the ball-bearing case fans begin crapping out after five years of 24/7 operation (five years powered-on, not five years OS uptime, of course).

    10. Re:Yea, but does it run Linux? by Anonymous Coward · · Score: 0

      How often do you actually install RAM and PCI cards on the typical Mac? More than once/year? I agree that the oven door looked cool, but it wasn't really all that helpful. The G5 boxes can still be opened without tools (there's a latch on the back that allows the right side to pop open), and RAM can also be installed without any tools. Also the G5 boxes can now be locked, where this was impossible on the G4s without cutting holes in the case.

    11. Re:Yea, but does it run Linux? by dhovis · · Score: 2, Informative

      You forget that Apple's thermal managment software is constantly monitoring things and if the temperature goes to high, the machine goes to sleep. In fact, the G4 Cube would sleep if you set something on top of it and blocked its ventilation. It didn't even have a fan.

      In fact, the 9 fans give you some amount of redundancy. Under normal operation, they turn at a low fraction (10%, IIRC) of their top speed to stay quiet (just 35dBA), so if one fails, the others can take up the slack with no problem. The fans should also last longer that way. They can probably put the "wind tunnel" macs to shame if they ever all get going at the same time.

      The failsafe on the software control is that if the software control is not present, the fans all go to full speed!

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      --
      The internet is the greatest source of biased information in the history of mankind.

    12. Re:Yea, but does it run Linux? by Anonymous Coward · · Score: 1, Informative

      locked ... G4 ... cutting

      Except maybe for that little tab with a hole and the icon of a lock on it that prevents case opening/removal if you put a padlock through it? :-)

    13. Re:Yea, but does it run Linux? by King+Babar · · Score: 2, Interesting
      There are two things (yeah, just two) I'm not 100% happy about on the G5 series:
      1. The relative lack of expandability (there are only two drive bays, for example, and both are already in used by default - one HD, one optical media)
      2. NINE FANS! Holy crap Apple, what the HELL were you thinking?!

      OK, so others have pointed out that you get two hard drive bays, and the SuperDrive is standard, making that a bit less of an issue in my mind.

      About the 9 fans, if they turn out to do a better job of managing heat than the 747-style fans in the dual-G4 I've got on my desk, they could put 15 fans in there and I'd still be thrilled. Seriously, the G4 case is splendid, but the cooling system on the latest dual processor models...somebody should have been shot for it to be this loud. (Okay, I'm fine now...)

      Another point about the apparent smallish number of hard drive bays is that I think this makes sense because we have crossed an important threshold:

      From now on, you'll want a disk or two at most on a desktop. If you need more storage, drink the kool-aid and get yourself a proper RAID.

      Honestly, the two disks the G5 will hold can bring you up to half a terabyte. Anymore than this, and arguably even *this* much, and what you really want is either a big old server in a closet somewhere or a RAID appliance of some kind. If you want to use the G5 itself as a server, as luck would have it, Apple also announced a nifty fibre channel PCI card that lets you attach the XRAID among other amusing devices.

      *My* only objection to the G5 machines is that I don't have one. (sniff)

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      Babar

    14. Re:Yea, but does it run Linux? by phillymjs · · Score: 3, Interesting

      The relative lack of expandability (there are only two drive bays, for example, and both are already in used by default - one HD, one optical media)

      Wrong. You get one optical, but there are two bays for SATA hard drives. So you have one unused bay. What I don't like is that there is no ATA backwards-compatibility, so it looks like I'll be buying an external FireWire case for the hard drive in my G4 now, if I want to keep it. I don't think you have the option of adding an ATA PCI card, either, because you'd have a tough time running the cable to the drive bay without interfering with the cooling zone setup.

      NINE FANS! Holy crap Apple, what the HELL were you thinking?! I mean, nine fans. That's NINE moving parts. And if any of them fail, presumably that's the end of a $3,000 computer.

      I'll tell you what they were thinking: Nine fans spinning slowly and quietly move as much air as the two or three fast-spinning, deafening fans in the average PC these days.

      Also, your $3000 G5 will be much better designed than the average PC. Have you seen the clear insert in behind the removable side panel that divides the cooling zones? That's not there just to look cool, it is there to properly duct the airflow to where it is needed in the mcahine. I read in one article that the computer will not even power on if THAT is not in its proper place-- so I'm feeling rather certain that Apple has taken fan failure into account, and if necessary you'll either get a warning and have a minute to do a graceful shutdown manually, or the computer will promptly, gracefully (or not) shut down on its own.

      ~Philly

    15. Re:Yea, but does it run Linux? by Watcher · · Score: 2, Insightful

      This may be a logical answer: its much easier for them to update the code running the fans from the OS than in firmware.

    16. Re:Yea, but does it run Linux? by Anonymous Coward · · Score: 0

      thats the only thing you care about? if it runs Linux?

      God, save me from these people. They are like the zombies in The Night of the Living Dead. All they do is ask "does it run Linux?" on any hardware posting ever made, anywhere on the net.

    17. Re:Yea, but does it run Linux? by coolgeek · · Score: 1

      betcha a dollar they GPL a driver for the fans.

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      cat /dev/null >sig
    18. Re:Yea, but does it run Linux? by afantee · · Score: 1

      >> The relative lack of expandability (there are only two drive bays, for example, and both are already in used by default - one HD, one optical media)

      There are 2 SATA drive bays for up to 500 GB internal storage, AND an optical Drive. Further more, you can always add external devices through USB2, Firewire 400 / 800, gigabit Ethernet.

      >> NINE FANS! Holy crap Apple, what the HELL were you thinking?! I mean, nine fans. That's NINE moving parts.

      This is a Good Thing - distributed cooling. If 1 of 9 fans fails, you are probably OK for a while. It would be much worse when 1 of 1 fan fails.

    19. Re:Yea, but does it run Linux? by MarkCollette · · Score: 1

      I think there are several factors:

      1. Like you said, ease of updating the code
      2. The OS can predict when the CPU, hard-drive, video card will get hotter since it knows when they're being used, and thus can turn up the fans in those areas a little before the use spikes, whereas sensors on the fans can only react to an already existing temperature increase - not as good
      3. Anything that forstalls Linux deployment on Apple PPC will mean increased sales of add-on software, including third-party software. This economically benefits Apple and its paying developer base.

    20. Re:Yea, but does it run Linux? by eswierk · · Score: 1
      What I don't like is that there is no ATA backwards-compatibility, so it looks like I'll be buying an external FireWire case for the hard drive in my G4 now, if I want to keep it.

      Or, you could buy a Serial ATA-to-IDE adapter for about 20 bucks and stick that old drive right in your new G5.

  7. Flying Toaster? Where did I see that before by Anonymous Coward · · Score: 0

    So, this thing generates enough heat to cause the iPod you left on top of it by mistake to look like a Dali watch?

    And it has fans to make it fly too? I saw this sort of flying toasting device depicted in a screen saver years ago.

    1. Re:Flying Toaster? Where did I see that before by Anomalous+Cowturd · · Score: 1


      And it has fans to make it fly too? I saw this sort of flying toasting device depicted in a screen saver years ago.


      Not to take away any credit from Berkeley Systems and After Dark, but the flying toasters thing originally came from Jefferson Airplane's 30 Seconds Over Winterland album cover.

      We now return you to your originally scheduled thread, already in progress.

      --

      Java: the bastard demon spawn of C++ and Ada

  8. Re:You guys are still at this? by Anonymous Coward · · Score: 0
  9. You guys are still at this, yourselves? by Anonymous Coward · · Score: 2, Funny

    Seriously, the self-perpetuating circle-jack that is trolling is really getting sad at this point. Let the rest of us know when you have a genuine point to make in a discussion. No-one forces you to read Slashdot.

  10. Ah yes, the early days! by dbirchall · · Score: 4, Interesting
    In April of 1990, I was visiting a friend at Utah State University in Logan, UT. The IBM rep (nice lady) came around to the computer center (which was nice of her) to try to sell everyone PS/2's - or at least PS/1's (which was less nice of her).

    But she brought this one thing with her that looked kind of like an overgrown PS/2, and had a goshawfulbig monitor hooked to it... and was running UNIX. Being a geek even back then, I noticed this and asked what it was and if I could play with it.

    'Twas some very early RS/6000 model, quite unstable at that point in time, OS-wise. I have no idea why she was allowed to bring it on campus. Maybe she was trying to convince them to move away from their Ultrix vaxen.

    By IBM's timeline, that would have been a POWER (no numbers after it) chip, predating the PowerPC by a chunk of time. I never stopped to think about it before, though.

    1. Re:Ah yes, the early days! by Anonymous Coward · · Score: 0

      I know this is gonna be taken as a troll, or off-topic, but wasn't (isn't it still?) IBM heavily relying on prison labour? Do we happen to condone prison labour by standing behind IBM in the SCO thing (given the recent comments by that FSF lawyer)?
      Supporting prison labour only promotes the war on drugs and such, doesn't it?

    2. Re:Ah yes, the early days! by fitten · · Score: 1

      Look at 1990 on this timeline:

      http://www.rootvg.net/column_risc.htm

  11. Multiply and add by Matthias+Wiesmann · · Score: 5, Interesting

    One thing that irks me in the low-end mac article is that it states that the G5 can do a multiply add in one cycle. While this is true, this is nothing special about the G5, the multiply and add instruction has been in the PowerPC instruction set since the start - my Powermac 7100 (technically à G1) already could do this. This is in fact pointed out in the intersting article by IBM about PowerPC.

    1. Re:Multiply and add by Duck_Taffy · · Score: 1

      Actually, your PM 7100 is technically a G2. G1s were 68k-based macs. G2s were PPC 60x-based, G3 is PPC 750-series processors, and of course PPC 74xx = G4, and PPC 970 series (so far) is the G5.

      --
      Karma: Ran over your dogma.
  12. Re:This is really cool by fputs(shit,+slashdot · · Score: 0

    I consider a dual G5 based rack-unit, without fancy cosmetics and get modded flamebait. Guess Apple making a cheap box that I can afford to fill a rack with in server room not be popular move with over zealous mods then?

    I wan't machine for processing power not looks so either deal with it or mod me down!

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    I am the bastard of base minus 12! Turing was the ejaculate of my complete machine!
  13. Apocalypse Now by Johnny+Mnemonic · · Score: 2, Funny


    Fast Macs, and trollaxor with a story submission. The apocalypse must be near now...

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    $tar -xvf .sig.tar
  14. I just think it's pointless until by BoomerSooner · · Score: 2, Interesting

    they get a damn OS that is built specifically for a 64bit processor instead of a 32bit patched. It's kind of like running DOS on a Pentium, pointless.

    1. Re:I just think it's pointless until by Lars+T. · · Score: 1

      Hey, as soon as I can buy a PC without a A20-gate to allow just that (running DOS on a Pentium - or anything from a 286 infact), I may buy one.

      --

      Lars T.

      To the guy who modded me down from perfect to terrible Karma - Apple haters still suck

    2. Re:I just think it's pointless until by dhovis · · Score: 4, Interesting

      Actually, that isn't really true. Because of the way the PPC ISA is set up, there isn't much advantage to switching the whole OS to pure 64 bit. The main boost you are going to see here is the ability to use more than 4GB memory, and you can implement that on the G5 with just a recompile.

      Individual apps can be switched to 64-bit and operate in 64-bit mode if needed, even if the OS doesn't use 64-bit mode itself, so long as the OS supports 64-bit addressing

      Unless you need to do 64bit integer math, your app will see no benefit from switching to pure 64-bit. In fact, your app may slow down and waste memory. But an app can still take advantage of the main benefit of more addressible memory whilest staying (essentially) a 32-bit app. This is thanks to the fact that PPC is a 64-bit architecture with a 32-bit subset.

      There are still optimizations that need to be done to improve the compilers for the G5, but very few of those optimizations have anything to do with being able to do 64-bit integer math.

      --

      --
      The internet is the greatest source of biased information in the history of mankind.

    3. Re:I just think it's pointless until by Anonymous Coward · · Score: 0

      I thought sometimes my mind was a "twisty little maze of passages, all alike"

    4. Re:I just think it's pointless until by Anomalous+Cowturd · · Score: 2, Funny

      Let's face it, the most relevant and useful thing we're likely to get from 64-bit desktop applications and systems is going to be the ability to keep time from ending in 2038.

      --

      Java: the bastard demon spawn of C++ and Ada

    5. Re:I just think it's pointless until by dhovis · · Score: 2, Funny

      Huh? Apple fixed that one years ago. The current Apple time implementation goes to the year 29,940. Apple claims to be hard at work on the Y30K problem, though.

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      --
      The internet is the greatest source of biased information in the history of mankind.

  15. Re:I DEMAND 401(k) by Anonymous Coward · · Score: 0

    shouldn't the image now be of a G FIVE processor as opposed the G4?

  16. whether the figures being offered are reliable by dpilot · · Score: 3, Interesting

    And of course they're being compared with P4 numbers that are now "mainstream." But when the P4 was first introduced, it was "peaky" and irregular, behaving much different from the well-understood PIII and K7 cores. AFAIK, aside from speed bumps, both internal and frontside, and cache size increases, it's still essentially the same "net-burst" core that received such mixed reviews on introduction. Oh, and quite a bit of compiler work, I'll guess, not to mention the new SysEnter stuff under Linux.

    Intel got much-deserved heat on the P4 introduction, though that seems forgotten now. IMHO the early irregular performance seems to have been handled by tweaking compilers and ramping speed until the valleys are mountain glens. For that matter, Merced seems largely forgotten with McKinley and Madison. Adoption has simply happened over time, because it's Intel.

    But there seems to be an air about that everyone else's (PPC970, K8) difficult launch is nearly fatal, and we should wait to adopt until these issues are ironed out. Of course many of them are volume-related and won't be fixed by anything but production and experience, same as P4 and I2.

    We seem to be a bunch of monopoly-making sheep, more times than just this one.

    --
    The living have better things to do than to continue hating the dead.
  17. Re:You guys are still at this? by presearch · · Score: 1

    would rather be force-fed whatever Apple wishes to shove down your throat.

    Yum!

  18. Hold up... RISC vs CISC, folks... by Eneff · · Score: 0

    Wasn't the PowerPC line supposed to be a RISC chip, anyway? Why would they (IBM, not the article) feel the need to proclaim that they support one more instruction, anyway?

    I'm sure we can find particular instances where the x86 has an instruction that the PPC doesn't have... after all, the PPC is supposed to gain its speed from having fewer instructions, right?

    ahhh head is spinning from too little sleep... beat with cluestick as necessary.

    1. Re:Hold up... RISC vs CISC, folks... by fitten · · Score: 2, Informative

      First, RISC vs. CISC arguments died about a decade ago. What was RISC became Load/Store architectures because they have load and store operations for memory access and everything else is register based. Most so called "RISC" machines tended to have nearly as many (if not more) instructions than their "CISC" counterparts.

      I posted a while back (sometime in the past year) the number of instructions a G4 (including Altavec) has compared to the P4 (including SSE2) and the G4 had quite a few more opcodes than the P4. Feel free to look the post up or do the same research.

  19. Floating Point Units by yarbo · · Score: 2, Informative

    comparison table the Athlon XP has 3 full FPUs, the P4 has a full and a partial (I believe it only can do memory operations, not arithmatic).

  20. But it's really only 32 bits by Anonymous Coward · · Score: 0
    1. Re:But it's really only 32 bits by dhovis · · Score: 2, Informative

      The frontside bus is two 32-bit wide unidirectional busses. They run at 500MHz DDR (equivelant to 1GHz). That gives you 4GB/s in each direction, per processor. The memory is 200MHz DDR (400MHz effective) and 128 bits wide (2 64bit banks), yielding total bandwith of 6.4GB/s (3.2GB/s per bank).

      The width of the FSB is really irrelevant here. The most important thing is how fast you can get data into and out of the processor. The thing that makes it a "64 bit processor" is that it can handle 64-bit memory pointers.

      I mean, heck. The G4 had a 64-bit FSB running at 167MHz, but that doesn't give it much bandwidth and it doesn't make it a 64-bit processor.

      --

      --
      The internet is the greatest source of biased information in the history of mankind.

    2. Re:But it's really only 32 bits by coolgeek · · Score: 2, Insightful

      You are trolling, right? Or do you just fail to realize that 32bits in each direction is one of the ways they achieve a 1Ghz FSB speed? By skipping the direction bit on the bus, they are saving a little propogation time, which leads to more cycles per second.

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      cat /dev/null >sig
    3. Re:But it's really only 32 bits by Anonymous Coward · · Score: 0

      So faster 32 bit busses, full duplex, makes it 64 bit? Wow. That 1GHz bus is awfully fast, are you sure you don't want to call it 128 bit instead? You know, since the bit width is now totally arbitrary.

    4. Re:But it's really only 32 bits by dhovis · · Score: 1

      No, 64-bit integer units make for a 64 bit processor. The G4 can use 36 bit pointers, but it severely complicates memory access because the pointer cannot be contained in one integer register. Further, IIRC, no single process can use more than 4GB by itself. The P4 and Xeon processors can do the same trick, but it slows memory access down considerably.

      What difference does bus width matter if it can transfer data faster than memory? The bus could be serial as far as it matters.

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      The internet is the greatest source of biased information in the history of mankind.

  21. Re:This is really cool by Anomalous+Cowturd · · Score: 1

    I think it might have had something to do with the "I know a couple of women with imacs, chosen because they matched the carpet or something" at the start of your comment, and the "fortunately I have better things to do than stare at in-animate objects".

    Obviously, you are not the target audience for a Macintosh. Now quit whining about moderation.

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    Java: the bastard demon spawn of C++ and Ada

  22. what RISC really means... by 5prite · · Score: 1

    the point is, RISC does not implies there are less instructions for you to use on the processor. What RISC actually means is that most instructions can be finished in one clock cycle (LOAD and STORE may be an exception) and all instructions are register based (as pointed out in sibling comment). Since all of its instructions are register-based, it can finish in one cycle (memory fetching takes definitely more than one cycle, compare your CPU clock to (effective) memory clock) and more importantly, it does not need to have messy instruction set which allows you to have four different type of source/destination combination (register -> register, memory -> register, register -> memory and memory -> memory).

  23. Fan Speed by Detritus · · Score: 1

    You can use fans with integral speed sensors. This allows the system software to detect failing or dead fans. I don't know if Apple uses them, but they have been available for many years.

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    Mea navis aericumbens anguillis abundat
  24. Wrong. by Anonymous Coward · · Score: 0

    68k Macs are just that, 68k Macs.

    601 based processor PowerMacs are G1
    603/604 base processor PowerMacs are G2.
    750 variants - G3
    74xx variants - G4
    970 - G5