DJZeMig_L
15-01-2004, 01:29 PM
Source.. Sound on Sound....
With the promise of improved battery life and more compact designs with no compromise in performance, Intel's Centrino technology should be the answer to the mobile musician's prayers. But does the promise hold true when running the most demanding music and audio software?
Mark Wherry
It's perhaps a fundamental irony that as studios become ever more powerful, requiring the computing power of small corporate networks in order to keep up with user expectations, the demand to be able to produce the same music on a portable system has never been greater. And while the idea of the laptop studio is nothing new, laptop computers themselves have many inherent flaws that particularly affect musicians, mostly because they concern the crucial issue of performance. Musicians need powerful computers to run the number of native-based effects and instruments they're accustomed to on the desktop; but in order to develop laptops, companies usually draw upon the same technology designed for desktop computers, and scale it down so it can basically fit in a smaller package.
The problem of using desktop-derived technology in a laptop can be summed up in two words: heat and power. The amount of processing power you require from your laptop is directly proportional to the amount of battery power that will be consumed, and the amount of heat that will be generated. It's almost a cliché these days that the last place you'd want to put a laptop is on your lap, since the heat that can be generated from G4- and Mobile Pentium 4-based laptops is terrific for frying eggs, but can make your computing experience rather painful. Suddenly, cool is not the word to describe those sexy metal enclosures — conductor would be far more appropriate.
In the past, Apple's Powerbooks have generally fared better than their Intel or AMD-based counterparts, thanks to the fact the G3 and G4 processors traditionally ran slightly cooler than Pentium III or 4 chips, and required less power. This fact has allowed Apple to produce Powerbooks that are powerful, but which still have reasonable battery lives and seductive form factors. Forgetting the heat issue for a moment, a G3- or G4-powered iBook or Powerbook (with the exception of some of the most recent Aluminium Powerbook models) has a typical battery life of around three to four hours, compared to around two hours for a typical Mobile Pentium 4-based system.
Courtesy of International Business Machines Corporation. Unauthorised use not permitted.
IBM's T40 is a robust, fully-featured Centrino laptop that has one of the longest battery run times of any notebook. It might not be as pretty as Apple's Aluminium competition, but with the cheapest model outperforming the most expensive Powerbook on the market, while weighing just 2.2kg, the T40 should be a serious contender for a musician's mobile rig.
But if I was to tell you about a laptop that had been built using technology specifically developed for mobile use, which could give you around eight hours of battery life while still providing a similar level of performance to desktop and other laptop computers, and without frying your legs, would you be interested? Of course you would. And if you haven't guessed already, I'm talking about the new range of Windows-based laptops featuring Intel's Centrino technology, which has been causing quite a stir in the computing world.
However, while the Centrino statistics should be whetting the appetite of laptop musicians, and despite Martin Walker's article comparing current laptop designs in the October 2003 issue of SOS (www.soundonsound.com/sos/oct03/articles/pcmusician.htm) there seem to be many myths about the supposed unsuitability of Centrino-based laptops for intensive computing applications such as music production. So in this article, I'm going to investigate the technology further and see if Intel have finally developed a solution to lure non-Logic users away from their Powerbooks.
Journey To The Centrino Of The Laptop
The Centrino brand name refers to the combination of three different Intel technologies: the Pentium-M processor, the 855 motherboard chip-set family (see the Meet The Family box), and the Pro/Wireless 2100 networking card. It's possible to purchase laptops featuring the Pentium-M processor and 855 chip set without Intel's network card, which, for the most part, have all the same benefits Centrino technology offers, but a laptop can't be branded with Intel's Centrino logo unless it features all three components. In this article, I'll be focussing mostly on the Pentium-M processor, since this is the most important component in terms of gauging the performance and suitability of Centrino laptops for audio applications, and when I refer to Centrino technology, my comments will be equally applicable to Pentium-M/855 laptops without Intel's Pro/Wireless networking hardware.
In contrast to earlier scaled-down desktop designs such as the Pentium 4 Mobile, the Pentium-M processor is a completely new processor designed specifically to meet the demands of mobile users. Intel admit that, compared to the desktop market, the mobile market hadn't been worth targeting until now; but with the continuing increase in demand for mobile technology, they decided that the time was right to directly target this sector.
Although based on a new design, the Pentium-M processor fully implements Intel's IA32 instruction set, which has provided the backbone for x86 processors since the 386 over 10 years ago — IA32 is also known as i386, which, incidentally, explains why you'll often find an i386 folder on your hard drive if you're running an NT-based version of Windows. The Pentium-M also contains both the MMX and SSE2 instruction sets. The latter was first implemented in Intel's Pentium 4 processor, and both contain commands that music and audio software developers can take advantage of to enhance their applications. This means that any application that's been optimised for the Pentium 4 via support for SSE2 or the older MMX instruction set, such as Cubase and Nuendo, will already be optimised for running on a Centrino-based laptop.
Meet The (855) Family
This block diagram shows clearly how the various Centrino components are handled by the 855-series chip set and the ICH4-M controller.
While the power consumption of the processor is obviously an issue in a mobile system, it isn't the only factor that affects battery life — or, in fact, the biggest factor. When developing the Pentium-M processor, Intel realised that it would only account for around 10 percent of the overall system's power consumption, with the LCD screen being, perhaps unsurprisingly, one of the biggest culprits for battery decimation. While graphics hardware developers are looking at this and other related issues, to assist power management in other areas of the system, Intel developed a new chip set around the Pentium-M processor with the same low-power, high-performance philosophy.
Centrino laptops are based around the 855 chip-set family, which is available in two versions: the 855PM and the 855GM. The fundamental difference between the two is that while the 855GM features an integrated graphics controller, the 855PM supports an AGP 4x interface for manufacturers to include additional high-performing graphics hardware into their laptop designs.
The 855 chip-set family design offers a 400MHz system buss with support for a maximum of 2GB 200/266/333 DDR memory, and a dynamic input and output buffer for activating and disabling memory and the processor system buss as required for saving power consumption. A hub connects the 855 chip set to an ICH4-M controller, which offers two Ultra ATA100 controllers, USB 2.0 (which is backwardly compatible with USB 1.1), an LCI (LAN Connect Interface) for Ethernet, an AC97 2.2 interface for the built-in audio and modem, and a PCI buss for the Cardbus interface and wireless networking hardware such as Intel's own Pro/Wireless 2100.
Cycle Races
There are many areas of a processor design that affect power consumption, some of the most important being the clock frequency and the amount of instruction-level parallelism, which is to say the number of instructions that are executed in a single clock cycle. Previous Mobile Pentium processors introduced a technology called Speedstep, which allowed processors to run at two different clock frequencies: the maximum clock frequency, for maximum performance when the laptop was running on mains power, for example, or if it was required when using batteries; and a reduced frequency which effectively made the processor run slower, and which was great for saving power when running on batteries if you weren't carrying out processor-intensive applications. The G4 used in Apple's current generation of Powerbooks features a similar two-step clock-switching technology.
The Pentium-M takes this idea further and features Enhanced Speedstep technology, which is able to switch through eight clock speeds and core voltages, rather than just two, as appropriate for a given load. Another improvement is that the steps between the speeds give smoother transitions, as opposed to the often noticeable 'jump' that happened with the first implementation of Speedstep — imagine the eight grades of Enhanced Speedstep being plotted on a curve, as opposed to an abrupt step. This technology is also able to disable parts of the processor that aren't required for a particular processing load, a feature which works effectively with the onboard low-power 1MB Level 2 cache. The biggest advantage of Enhanced Speedstep is that it enables you, with a bit of thought, to scale your processor's performance to match a given situation.
As an example, while Gigastudio 2.5 is fairly processor-intensive, the fact it has a voice limit of 160 means that it doesn't require all of the available processing of a Pentium-M processor. In this way, you can reduce the CPU operating frequency, meaning that your mobile Gigastudio rig stays running for longer since more of its battery power is available to the hard drive, for example. As a footnote, Enhanced Speedstep technology is also available in Intel's most recent Mobile Pentium 4 processors (see the 4-Gone Conclusion box).
Clear Instructions
Making the processor run slower can save battery power, but naturally impedes performance. To save power without impeding performance, the CPU can also be designed to carry out a given task by executing fewer instructions. And while the number of instructions required for a task isn't a matter that's actually open for debate, there are many techniques chip designers can employ to improve the efficiency of the processor's ability in this area, such as branch prediction.
Although it's a complicated subject, the basic idea behind branch prediction is that where a program's code loops a number of times based on a certain condition, there's a good chance the condition will be the same when it loops again, meaning that the code branches back to the same instruction as before. In this way, the processor's branch predictor can assume this will be the case and make sure the instruction it expects the program to branch to is ready for execution. If the assumed outcome of the branch turns out to be incorrect, the processor can simply retrieve the correct instruction; but if the assumed outcome is true, the instruction is already next in line, which speeds up the overall execution. While this is perhaps an oversimplification, it should give you an idea of the basic principle.
In essence, the way branch prediction saves power is that it means the processor doesn't have to burn power waiting for the next instruction to execute, and can effectively shut down and reduce its power consumption sooner. Branch prediction is also used in desktop processors as well, of course, since the saving in processing time benefits performance (as you can do more in less time), and the Pentium-M's branch predictor is actually based on same design used for the Pentium 4 processor. However, for laptops, the advantage of advanced branch prediction is a two-fold gain because you get both better performance and reduced power overheads; and while such branch prediction itself requires additional power, the overall consumption is lower in comparison to using simpler branch prediction logic or none at all.
Another place where Intel looked at saving power is when you're not actually using your laptop, which is to say when you put it to sleep, as opposed to shutting it down via Windows' useful Hibernate mode, which basically dumps the entire contents of your computer's memory to disk before switching off completely. And so, accordingly, the Pentium-M features three sleep modes, given the not-so-terribly interesting names of Sleep, Deep Sleep and Deeper Sleep, which put the processor into accordingly less power-consuming modes of operation, while still retaining a degree of 'context', as per Intel's description. This basically means you can keep your laptop ready for action without having to switch it completely off, and without having to worry about the battery draining away while you're not actually using your system.
Cardbus Audio
The big problem with Windows-based laptops from a musician's perspective is always the lack of built-in low-latency audio hardware, compared to Apple's Powerbook range. As mentioned in the main text, this is something that will change with the next generation of chip sets, but in the meantime, musicians have two options. Firstly, you could try the ASIO2KS driver (www.asio2ks.de), which is a generic ASIO driver for WDM-compatible audio hardware that's still in beta testing; but the better option would be to purchase a suitable audio converter that's supplied with its own dedicated ASIO drivers. This latter option will usually provide the best performance (in terms of relieving the load on your laptop's CPU), and will usually have higher quality audio parts.
Since many Windows laptops have Cardbus expansion slots, these are usually the preferable option for most users, as many Cardbus audio products are self-contained and don't require you to carry an additional breakout box. The two main product lines that fall into this category are Echo's Indigo and Digigram's PCXpocket and VXpocket. Echo are a relative newcomer to the laptop audio market, but the company's low-priced products have already proven popular, and I have an original Echo Indigo myself for personal use, as reviewed in the July 2003 issue of SOS.
The great thing about Echo's Indigo drivers is that they can support both ASIO and GSIF (for Gigastudio) driver models simultaneously, enabling me to run Cubase SX with a variety of plug-ins alongside Gigastudio. The basic Echo Indigo card provides two identical stereo 3.5mm headphone outputs along with a volume control, which is perfect since I don't require an audio input. For those who do require an audio input, there's the Indigo IO card, and Echo also offer the Indigo DJ card, which is similar to the original Indigo except that the two outputs are treated independently.
Digigram's VXpocket interface has long been popular with laptop musicians, and the latest incarnations, v2 and 440, feature either two or four balanced mic/line-level input and output ports respectively, and both cards also feature S/PDIF input and output. Digigram also offer the PCXpocket series of interfaces, which include onboard DSP power for codecs such as MPEG Layers I, II and III and MPEG-2 Audio, and real-time frequency and format conversion when used with the appropriate software. There are three PCXpocket models available: the 240, featuring two balanced stereo mic/line-level inputs and one unbalanced stereo output; the 440, which has two balanced stereo mic/line-level inputs, two balanced stereo outputs, and S/PDIF I/O; and, finally, the v3, featuring a balanced stereo mic/line-level input, a balanced stereo output, and S/PDIF I/O. Check out Digigram's web site at www.digigram.com for more information.
RME also offer Cardbus versions of their Hammerfall DSP card, with a choice of either the Digiface (mainly digital I/O)and Multiface (mainly analogue I/O) breakout boxes. This system, along with its desktop counterpart, was reviewed in September 2002's SOS as Steinberg's Nuendo Audiolink 96 system (www.soundonsound.com/sos/sep02/articles/audiolink.asp). The big advantage with the mobile Hammerfall DSP is that the Cardbus interface offers the same DSP functionality as the PCI versions, with onboard monitor mixing and the Digicheck analysis tools. The big disadvantage is that the Multiface and Digiface interfaces themselves require an external power source, making them less than ideal for recording the sound of dairy cows in their natural habitat, for example.
Thinkpad Different
In order to test the actual performance of a Centrino laptop, I used an IBM Thinkpad T40 featuring a 1.3GHz Pentium-M processor, 768MB DDR PC2100 RAM (the standard model comes with 256MB), 32MB ATI Mobility Radeon 7500 graphics with a 14-inch 1024 x 768 XGA display, a 40GB, 5400rpm hard drive, a 16/10/24/8-speed CD-RW/DVD-ROM optical drive, and an Intel 802.11b adaptor, making this a true Centrino laptop, weighing in at just 2.2kg with a thickness of 2.7cm. For weight and size comparisons, the Aluminium 15-inch Powerbook is 2.5kg and 2.8cm, the 12-inch G4 iBook is 2.2kg and 3.42cm, while on the Mobile Pentium 4 front, the Millennium Music laptop PC reviewed in September's SOS is 4.4cm thick and weighs 4.4kg — exactly double the weight of the iBook and T40.
The T40 brims with clever IBM technologies, but the highlight for most will be the battery life: in true Centrino style, the standard lithium-ion (or Li-ion for short) battery offers around four to five hours of battery life, with the brightness set to a usable 50 percent, and the processor performance adjusted to its second-highest setting — expect around three to four hours with maximum brightness and processor settings. This is great, of course, but IBM also offer a high-capacity Li-ion that comes as standard with higher-end T40 models; and although this protrudes about thumb-depth over three quarters of the back panel, it offers a staggering eight to nine hours of battery life if you're being economical, and around five to six if you're not.
Most of the major laptop manufacturers are offering their own Centrino machines, such as the Maxdata model reviewed in last month's SOS.
While typical Mobile Pentium 4 and G4-based laptops can achieve similar levels of battery life if you carry multiple batteries around, this not only adds to the overall weight of your laptop bag, but soon becomes a hassle in terms of battery charging management. With its high-capacity battery, the T40 is one of the most desirable Centrino laptops available, despite more aesthetically attractive offerings from Samsung and Sony. And should you require even more battery life, you can remove the optical drive at the appropriate moment and replace it with an additional battery while the T40 is still running. This means you can run a laptop for the entire length of a transatlantic flight, without restarting. It also means you generally don't have to carry your laptop charger around, which can be quite a liberating feeling in itself!
I have to confess that I do sit in bed watching DVDs... I mean writing music with my laptop, and it's in these situations you really don't want your computer to get unpleasantly warm. Having tried this manoeuvre unsuccessfully with both the previous Titanium G4 Powerbooks and conventional Mobile Pentium 4-based notebooks, the T40 passed this 'Wherry laptop leg-roast' challenge with flying colours, although you'll have to take my word for this as shame prevents me from providing the necessary photographic evidence!
Getting back to the specifications, the T40's aforementioned 5400rpm drive allowed me to play a large piano instrument in Gigastudio with full 160-voice polyphony without breaking into a sweat, making it an ideal portable Gigastudio rig. In fact, most of the time I'm running Gigastudio with Cubase, or Gigastudio with Outlook, Mozilla Firebird, Word and Sibelius, and I'd never even dream I was trying to do something remotely clever in terms of my computing requirements. And of course, I'm not, if you consider the typical performance of a desktop system. But the combination of laptop performance with this level of power economy has never been seen before — and that's what impresses me. As an aside, a T40-owning friend surprised an Avid engineer by getting better performance than Avid-approved mobile systems on his T40 when running Xpress Pro!
No Smoke Without Firewire
The T40's two 32-bit Cardbus slots allow connectivity for audio hardware and Firewire cards, which, in fact, highlights my only possible criticism of the T40 from the audio and video user's perspective: the lack of a built-in Firewire port. Actually, for me, this wasn't such a big deal as for drives, I'd rather fit a bigger and faster internal drive if I needed the performance and capacity (see the Drive On box); and for audio hardware, I tend to prefer the Cardbus solutions for mobile use (see the Cardbus Audio box). However, I know that these are important considerations for some users, so while it sounds like a bland catch-all, this is one area where is really depends on how you plan to use your laptop in a given situation.
On the subject of connectivity, the T40 does, however, feature two USB 2.0 ports (thanks to the 855PM chip set), a modem, 10/100 Base-T Ethernet, a traditional parallel port, and S-Video and VGA ports for graphics. These latter two ports are supported by the internal ATI Radeon 7500 controller, connected via an AGP 4x interface, providing either mirroring or spanning; and while a DVI connector might have been nice, the T40's optional docking station provides such a port, along with the ability to house a half-length PCI card.
While this isn't a T40 review, if you hadn't guessed, I actually liked the laptop so much that I bought one. Considering the convenience and the fact it runs Nuendo, Cubase, Sibelius, Gigastudio and a host of plug-ins alongside Office, Visual Studio, Photoshop and other non-musical applications, the T40 has proven itself to be one of the most useful Windows machines I've owned. However, since I bought my T40, IBM have, of course, introduced the T41 range, which, for the most part, seems to offer the features found in the previous high-end T40 models at a more reasonable price point, including the 1400 x 1050 14-inch display, along with the fastest 1.7GHz Pentium-M chips and improved graphics chip sets with 128MB video memory. If you're looking for the ultimate portability and can live without a built-in optical drive, IBM's X series offers a light 1.64kg, less-than-an-inch-thick form factor featuring a 12-inch 1024 x 786, a Cardbus slot for your audio interface, a Firewire port, and a CF slot, which might be handy if you're a keen digital photographer.
The laptop in the hearts of most mobile musical geeks at the moment has to be IBM's new 1.5-inch-thick R50p, which features a gorgeous 15-inch 1600 x 1200 display, and the fastest 1.7GHz Pentium-M processor. It comes loaded with 512MB 333MHz RAM, upgradeable to 2GB (like the T40), an ATA100, 7200rpm, 60GB internal drive (see Drive On box), ATI's Mobility FireGL T2 graphics card with 128MB VRAM, a recordable DVD drive, gigabit Ethernet, an integrated 802.11a/b/g-compatible wireless card, and, oh, a battery life of nearly six hours! The only down side is the weight: 3.6kg, which is 400g or so heavier than Apple's 17-inch Powerbook. However, if you're talking a desktop replacement music machine, it's a case of game, set and match to the R50p. Rather a shame that it currently retails for about 4000 dollars in the US before sales tax.
IBM aren't the only computer manufacturer producing Centrino-based laptops, and other mainstream companies such as Samsung, Sony, HP and Toshiba also offer tempting products. However, IBM seem to offer the best battery lives with their extended batteries, and I personally have had good experiences with their machines.
Drive On
Until now, most laptop hard drives have offered lower spindle speeds and hence lower data transfer rates than those commonly used in desktop PCs, but new models such as the Travelstar E7K60 now boast a fast 7200rpm rotation speed.
Although the IBM T40 laptop mentioned in this article features a fast (for a laptop) 5400rpm drive, for those who require the ultimate mobile performance, it's worth mentioning that Hitachi Global Storage Technologies (HGST) are now offering 7200rpm Travelstar drives in up to 60GB capacities for laptop users. For those who like to know these things, HGST (www.hgst.com) was formed in 2003 when IBM and Hitachi merged their respective storage divisions, and the company now handles all of IBM's previous hard drive products, such as the Deskstar line.
The E7K60 Travelstar drive in question can be yours for $290, features low power consumption (with minimum heat), and is designed for intensive, always-on applications such as blade servers — two factors that make it more than suitable for audio (and video) work. You can find out more information about these drives at www.hgst.com/hdd/travel/tre7k60.htm, including white papers and purchasing information. A consumer-orientated 7K60 model is also available, which is slightly cheaper and isn't designed for 'always-on' performance, and this is the drive that laptop manufacturers such as IBM supply with machines such as the T41 and R50p.
Laptop Bake-off
If the proof of the pudding is in the eating, the proof of the laptop for musicians is surely in how much DSP power it provides for native-based applications, so I decided to run a few tests to see just how two T40 models stacked up against Apple's 17-inch Powerbook and a conventional Mobile Pentium 4-based laptop. In terms of audio hardware, I used the same Echo Indigo PCMCIA card on every system (see Laptop Audio box), although I also tried using the internal headphone output on the 17-inch Powerbook, which actually gave me exactly the same results in terms of CPU performance.
Of the two T40 models I used, one was a T40p with a 1.6GHz Pentium-M with 512MB RAM and ATI Mobility FireGL 9000 graphics with 64MB RAM, and the other was a standard T40 with a 1.3GHz Pentium-M and 768MB RAM, as described in the last section. The 17-inch Powerbook in question was the latest generation 1.33GHz G4 model with 1GB RAM and ATI Mobility Radeon 9600 graphics with 64MB RAM. And, finally, the Mobile Pentium 4 laptop used was a Compaq Evo N800w with a 2.2GHz Mobile Pentium 4, 1GB RAM, and also featured an ATI FireGL 9000 graphics chip set with 64MB RAM.
Figure 1: This graph shows the results from the test described in the main text. The solid colour shows the number of Reverb A plug-ins that could be run until the audio started failing, while the lighter region shows the number of plug-ins before the processor actually maxed out.
Conducting a fair performance test across multiple platforms is difficult, so I tried to come up with a situation that was relevant, simple, and as fair as possible. Using the latest version of Cubase SX 2, I created a test Project to see how many Reverb A plug-ins could be used, with a single A1 virtual synth rather than an audio file used as the audio source in order to keep the load on the computer focussed on the processing and avoid factoring in the varying overheads of hard disks and their associated controllers. The reverb plug-ins were placed as inserts on FX Channel Tracks rather than inserts on the A1 Channel itself, in order to keep the environment as consistent as possible when scaling the test beyond the eight insert effects allowed per Channel. Finally, all the gain controls (including the sends) were kept at 0dB, except the Master fader, which was set so there was no audible distortion.
I'll resist the urge to use some colourful metaphors to describe the results of the tests because, as you can see by the graph in Figure 1, overleaf, the outcome is easy to evaluate. Centrino-powered laptops are clearly as powerful as their Mobile Pentium 4 counterparts, with the 1.3GHz model offering the same level of performance as the 2.2GHz Mobile Pentium-4 system. And while the Centrino is admittedly a little more expensive than the Mobile Pentium 4, it offers the same performance with three or four times the battery life, and in a lighter, smaller form factor that doesn't get anywhere near as hot. After I ran the test, it would have actually been painful to touch the bottom of the N800w for more than a second, while the T40 remained casually warm.
Perhaps the biggest surprise was the relative performance of the 17-inch Powerbook. While it's fairly well-known that the G4's performance has been falling behind the competition, if you consider how much more you'll pay for this model over the Windows-based systems, and the fact that this is the highest-performing portable Mac money can buy, these facts would make me consider purchasing a Mac laptop only if I absolutely had to work on a Mac.
An interesting point about the Mac test was that even when the audio was breaking up, the actual responsiveness of the system, in terms of the user interface, wasn't impaired — something that could definitely not be said of the Windows-based systems. This is fairly easy to explain: Mac OS X's Quartz Extreme technology offloads a large proportion of its Aqua user interface graphics processing to the graphics card, so its performance is constant no matter the load on the system's main CPU. In some ways this fact reflects poorly on the G4, since the Intel processors achieve more DSP while running the bulk of the user interface as well, but it does reflect well on the architecture of OS X itself for processor-intensive media applications. Intel and AMD users might expect to see these kinds of technologies in Microsoft's next-generation Windows operating system, Longhorn, although we may not see this until 2005 or 2006.
4-gone Conclusion
Centrino-based laptops are powerful enough for digital media applications, although it's worth mentioning that Intel still have other solutions for mobile users in their Mobile Pentium 4 product line. While Centrino technology shows the ultimate direction for Intel's mobile strategy, considering the revised Dothan Pentium-M chip due next year, Intel are still continuing to improve their Mobile Pentium 4 chip line, with a recent revision including 533MHz front side busses, as opposed to the 400MHz variety used in previous Mobile Pentium 4 and Pentium-M designs.
These new Mobile Pentium 4 processors are derived from the Pentium 4 processors used in desktop computers, and although Intel offer a range of clock speeds from 2.4GHz to 3.06GHz in their mobile offerings, they omit the Hyperthreading technology, presumably to allow for cooler and more economical operation. The processors feature a 512k L2 cache, and when used with Intel's 852PM and 852GME chip sets, they can scale down to 1.6GHz for power conservation.
For those who require the most processing power available in a portable system — portable rather than mobile — a Mobile Pentium 4 system might be worth considering, especially given that it will be cheaper than a similarly equipped 1.7GHz Pentium-M system. Budget permitting, however, the benefits of the Centrino technology would lead me in that direction every time.
Left, Right & Centrino
With Centrino, Intel have finally liberated Windows-based laptop manufacturers from the burden of bulky, hot and battery-intensive technology; and forgetting the Windows operating system for a moment, it's hard to see who wouldn't want a powerful, cool and long-lasting laptop. Aside from aesthetics, the only two advantages that remain for Apple's range of laptops, in my opinion, is that they all have a built-in low-latency audio system and a Firewire port as standard, saving you from having to purchase an additional converter such as the Echo Indigo or, indeed, a Firewire card. This is obviously a big advantage for a musician, although if you need more than a single stereo input and output, you'll have to buy an additional converter anyway. And while some Centrino-based laptops do feature Firewire connectivity (the T40 aside), all feature USB 2 ports, and we're already starting to see the emergence of USB 2 audio hardware from companies such as Edirol.
Technology rarely stands still in this world, and at recent Intel Developer Forum events, the company have already announced Sonoma, the next generation of Centrino technology. Sonoma is based on Dothan, a revision of the Pentium-M processor due in the second half of 2004 that will feature a 2MB on-chip cache and over twice the performance of the current high-end 1.7GHz Pentium-M. Sonoma also features Alviso, a new motherboard chip set that will provide enhanced graphics and support for Serial ATA devices, and Express Card, which is based on PCI Express (an Intel development of the current PCI buss) to provide thinner and lighter expansion cards.
Of specific interest to mobile musicians is that the code-name-crazy Sonoma will also implement Azalia, Intel's next-generation PC audio technology, which will offer Dolby 7.1 playback and consume around the same power as current AC97-based laptop audio systems. Azalia should also allow for an overall improvement in the performance of a laptop's built-in audio capabilities, which should make it possible to work from the built-in headphone socket with minimal latency as Powerbook users can right now.
Until these technologies become available, I'm in no doubt that from a technical perspective, the most suitable laptops for the demands of mobile musicians are powered by Intel's Centrino technology. I'm excited to see what Apple do with their next range of Powerbooks, of course; but for now, when I leave the house, it's an IBM T40 that will be my music-making companion because in terms of performance and mobility, nothing else comes close.
Z
With the promise of improved battery life and more compact designs with no compromise in performance, Intel's Centrino technology should be the answer to the mobile musician's prayers. But does the promise hold true when running the most demanding music and audio software?
Mark Wherry
It's perhaps a fundamental irony that as studios become ever more powerful, requiring the computing power of small corporate networks in order to keep up with user expectations, the demand to be able to produce the same music on a portable system has never been greater. And while the idea of the laptop studio is nothing new, laptop computers themselves have many inherent flaws that particularly affect musicians, mostly because they concern the crucial issue of performance. Musicians need powerful computers to run the number of native-based effects and instruments they're accustomed to on the desktop; but in order to develop laptops, companies usually draw upon the same technology designed for desktop computers, and scale it down so it can basically fit in a smaller package.
The problem of using desktop-derived technology in a laptop can be summed up in two words: heat and power. The amount of processing power you require from your laptop is directly proportional to the amount of battery power that will be consumed, and the amount of heat that will be generated. It's almost a cliché these days that the last place you'd want to put a laptop is on your lap, since the heat that can be generated from G4- and Mobile Pentium 4-based laptops is terrific for frying eggs, but can make your computing experience rather painful. Suddenly, cool is not the word to describe those sexy metal enclosures — conductor would be far more appropriate.
In the past, Apple's Powerbooks have generally fared better than their Intel or AMD-based counterparts, thanks to the fact the G3 and G4 processors traditionally ran slightly cooler than Pentium III or 4 chips, and required less power. This fact has allowed Apple to produce Powerbooks that are powerful, but which still have reasonable battery lives and seductive form factors. Forgetting the heat issue for a moment, a G3- or G4-powered iBook or Powerbook (with the exception of some of the most recent Aluminium Powerbook models) has a typical battery life of around three to four hours, compared to around two hours for a typical Mobile Pentium 4-based system.
Courtesy of International Business Machines Corporation. Unauthorised use not permitted.
IBM's T40 is a robust, fully-featured Centrino laptop that has one of the longest battery run times of any notebook. It might not be as pretty as Apple's Aluminium competition, but with the cheapest model outperforming the most expensive Powerbook on the market, while weighing just 2.2kg, the T40 should be a serious contender for a musician's mobile rig.
But if I was to tell you about a laptop that had been built using technology specifically developed for mobile use, which could give you around eight hours of battery life while still providing a similar level of performance to desktop and other laptop computers, and without frying your legs, would you be interested? Of course you would. And if you haven't guessed already, I'm talking about the new range of Windows-based laptops featuring Intel's Centrino technology, which has been causing quite a stir in the computing world.
However, while the Centrino statistics should be whetting the appetite of laptop musicians, and despite Martin Walker's article comparing current laptop designs in the October 2003 issue of SOS (www.soundonsound.com/sos/oct03/articles/pcmusician.htm) there seem to be many myths about the supposed unsuitability of Centrino-based laptops for intensive computing applications such as music production. So in this article, I'm going to investigate the technology further and see if Intel have finally developed a solution to lure non-Logic users away from their Powerbooks.
Journey To The Centrino Of The Laptop
The Centrino brand name refers to the combination of three different Intel technologies: the Pentium-M processor, the 855 motherboard chip-set family (see the Meet The Family box), and the Pro/Wireless 2100 networking card. It's possible to purchase laptops featuring the Pentium-M processor and 855 chip set without Intel's network card, which, for the most part, have all the same benefits Centrino technology offers, but a laptop can't be branded with Intel's Centrino logo unless it features all three components. In this article, I'll be focussing mostly on the Pentium-M processor, since this is the most important component in terms of gauging the performance and suitability of Centrino laptops for audio applications, and when I refer to Centrino technology, my comments will be equally applicable to Pentium-M/855 laptops without Intel's Pro/Wireless networking hardware.
In contrast to earlier scaled-down desktop designs such as the Pentium 4 Mobile, the Pentium-M processor is a completely new processor designed specifically to meet the demands of mobile users. Intel admit that, compared to the desktop market, the mobile market hadn't been worth targeting until now; but with the continuing increase in demand for mobile technology, they decided that the time was right to directly target this sector.
Although based on a new design, the Pentium-M processor fully implements Intel's IA32 instruction set, which has provided the backbone for x86 processors since the 386 over 10 years ago — IA32 is also known as i386, which, incidentally, explains why you'll often find an i386 folder on your hard drive if you're running an NT-based version of Windows. The Pentium-M also contains both the MMX and SSE2 instruction sets. The latter was first implemented in Intel's Pentium 4 processor, and both contain commands that music and audio software developers can take advantage of to enhance their applications. This means that any application that's been optimised for the Pentium 4 via support for SSE2 or the older MMX instruction set, such as Cubase and Nuendo, will already be optimised for running on a Centrino-based laptop.
Meet The (855) Family
This block diagram shows clearly how the various Centrino components are handled by the 855-series chip set and the ICH4-M controller.
While the power consumption of the processor is obviously an issue in a mobile system, it isn't the only factor that affects battery life — or, in fact, the biggest factor. When developing the Pentium-M processor, Intel realised that it would only account for around 10 percent of the overall system's power consumption, with the LCD screen being, perhaps unsurprisingly, one of the biggest culprits for battery decimation. While graphics hardware developers are looking at this and other related issues, to assist power management in other areas of the system, Intel developed a new chip set around the Pentium-M processor with the same low-power, high-performance philosophy.
Centrino laptops are based around the 855 chip-set family, which is available in two versions: the 855PM and the 855GM. The fundamental difference between the two is that while the 855GM features an integrated graphics controller, the 855PM supports an AGP 4x interface for manufacturers to include additional high-performing graphics hardware into their laptop designs.
The 855 chip-set family design offers a 400MHz system buss with support for a maximum of 2GB 200/266/333 DDR memory, and a dynamic input and output buffer for activating and disabling memory and the processor system buss as required for saving power consumption. A hub connects the 855 chip set to an ICH4-M controller, which offers two Ultra ATA100 controllers, USB 2.0 (which is backwardly compatible with USB 1.1), an LCI (LAN Connect Interface) for Ethernet, an AC97 2.2 interface for the built-in audio and modem, and a PCI buss for the Cardbus interface and wireless networking hardware such as Intel's own Pro/Wireless 2100.
Cycle Races
There are many areas of a processor design that affect power consumption, some of the most important being the clock frequency and the amount of instruction-level parallelism, which is to say the number of instructions that are executed in a single clock cycle. Previous Mobile Pentium processors introduced a technology called Speedstep, which allowed processors to run at two different clock frequencies: the maximum clock frequency, for maximum performance when the laptop was running on mains power, for example, or if it was required when using batteries; and a reduced frequency which effectively made the processor run slower, and which was great for saving power when running on batteries if you weren't carrying out processor-intensive applications. The G4 used in Apple's current generation of Powerbooks features a similar two-step clock-switching technology.
The Pentium-M takes this idea further and features Enhanced Speedstep technology, which is able to switch through eight clock speeds and core voltages, rather than just two, as appropriate for a given load. Another improvement is that the steps between the speeds give smoother transitions, as opposed to the often noticeable 'jump' that happened with the first implementation of Speedstep — imagine the eight grades of Enhanced Speedstep being plotted on a curve, as opposed to an abrupt step. This technology is also able to disable parts of the processor that aren't required for a particular processing load, a feature which works effectively with the onboard low-power 1MB Level 2 cache. The biggest advantage of Enhanced Speedstep is that it enables you, with a bit of thought, to scale your processor's performance to match a given situation.
As an example, while Gigastudio 2.5 is fairly processor-intensive, the fact it has a voice limit of 160 means that it doesn't require all of the available processing of a Pentium-M processor. In this way, you can reduce the CPU operating frequency, meaning that your mobile Gigastudio rig stays running for longer since more of its battery power is available to the hard drive, for example. As a footnote, Enhanced Speedstep technology is also available in Intel's most recent Mobile Pentium 4 processors (see the 4-Gone Conclusion box).
Clear Instructions
Making the processor run slower can save battery power, but naturally impedes performance. To save power without impeding performance, the CPU can also be designed to carry out a given task by executing fewer instructions. And while the number of instructions required for a task isn't a matter that's actually open for debate, there are many techniques chip designers can employ to improve the efficiency of the processor's ability in this area, such as branch prediction.
Although it's a complicated subject, the basic idea behind branch prediction is that where a program's code loops a number of times based on a certain condition, there's a good chance the condition will be the same when it loops again, meaning that the code branches back to the same instruction as before. In this way, the processor's branch predictor can assume this will be the case and make sure the instruction it expects the program to branch to is ready for execution. If the assumed outcome of the branch turns out to be incorrect, the processor can simply retrieve the correct instruction; but if the assumed outcome is true, the instruction is already next in line, which speeds up the overall execution. While this is perhaps an oversimplification, it should give you an idea of the basic principle.
In essence, the way branch prediction saves power is that it means the processor doesn't have to burn power waiting for the next instruction to execute, and can effectively shut down and reduce its power consumption sooner. Branch prediction is also used in desktop processors as well, of course, since the saving in processing time benefits performance (as you can do more in less time), and the Pentium-M's branch predictor is actually based on same design used for the Pentium 4 processor. However, for laptops, the advantage of advanced branch prediction is a two-fold gain because you get both better performance and reduced power overheads; and while such branch prediction itself requires additional power, the overall consumption is lower in comparison to using simpler branch prediction logic or none at all.
Another place where Intel looked at saving power is when you're not actually using your laptop, which is to say when you put it to sleep, as opposed to shutting it down via Windows' useful Hibernate mode, which basically dumps the entire contents of your computer's memory to disk before switching off completely. And so, accordingly, the Pentium-M features three sleep modes, given the not-so-terribly interesting names of Sleep, Deep Sleep and Deeper Sleep, which put the processor into accordingly less power-consuming modes of operation, while still retaining a degree of 'context', as per Intel's description. This basically means you can keep your laptop ready for action without having to switch it completely off, and without having to worry about the battery draining away while you're not actually using your system.
Cardbus Audio
The big problem with Windows-based laptops from a musician's perspective is always the lack of built-in low-latency audio hardware, compared to Apple's Powerbook range. As mentioned in the main text, this is something that will change with the next generation of chip sets, but in the meantime, musicians have two options. Firstly, you could try the ASIO2KS driver (www.asio2ks.de), which is a generic ASIO driver for WDM-compatible audio hardware that's still in beta testing; but the better option would be to purchase a suitable audio converter that's supplied with its own dedicated ASIO drivers. This latter option will usually provide the best performance (in terms of relieving the load on your laptop's CPU), and will usually have higher quality audio parts.
Since many Windows laptops have Cardbus expansion slots, these are usually the preferable option for most users, as many Cardbus audio products are self-contained and don't require you to carry an additional breakout box. The two main product lines that fall into this category are Echo's Indigo and Digigram's PCXpocket and VXpocket. Echo are a relative newcomer to the laptop audio market, but the company's low-priced products have already proven popular, and I have an original Echo Indigo myself for personal use, as reviewed in the July 2003 issue of SOS.
The great thing about Echo's Indigo drivers is that they can support both ASIO and GSIF (for Gigastudio) driver models simultaneously, enabling me to run Cubase SX with a variety of plug-ins alongside Gigastudio. The basic Echo Indigo card provides two identical stereo 3.5mm headphone outputs along with a volume control, which is perfect since I don't require an audio input. For those who do require an audio input, there's the Indigo IO card, and Echo also offer the Indigo DJ card, which is similar to the original Indigo except that the two outputs are treated independently.
Digigram's VXpocket interface has long been popular with laptop musicians, and the latest incarnations, v2 and 440, feature either two or four balanced mic/line-level input and output ports respectively, and both cards also feature S/PDIF input and output. Digigram also offer the PCXpocket series of interfaces, which include onboard DSP power for codecs such as MPEG Layers I, II and III and MPEG-2 Audio, and real-time frequency and format conversion when used with the appropriate software. There are three PCXpocket models available: the 240, featuring two balanced stereo mic/line-level inputs and one unbalanced stereo output; the 440, which has two balanced stereo mic/line-level inputs, two balanced stereo outputs, and S/PDIF I/O; and, finally, the v3, featuring a balanced stereo mic/line-level input, a balanced stereo output, and S/PDIF I/O. Check out Digigram's web site at www.digigram.com for more information.
RME also offer Cardbus versions of their Hammerfall DSP card, with a choice of either the Digiface (mainly digital I/O)and Multiface (mainly analogue I/O) breakout boxes. This system, along with its desktop counterpart, was reviewed in September 2002's SOS as Steinberg's Nuendo Audiolink 96 system (www.soundonsound.com/sos/sep02/articles/audiolink.asp). The big advantage with the mobile Hammerfall DSP is that the Cardbus interface offers the same DSP functionality as the PCI versions, with onboard monitor mixing and the Digicheck analysis tools. The big disadvantage is that the Multiface and Digiface interfaces themselves require an external power source, making them less than ideal for recording the sound of dairy cows in their natural habitat, for example.
Thinkpad Different
In order to test the actual performance of a Centrino laptop, I used an IBM Thinkpad T40 featuring a 1.3GHz Pentium-M processor, 768MB DDR PC2100 RAM (the standard model comes with 256MB), 32MB ATI Mobility Radeon 7500 graphics with a 14-inch 1024 x 768 XGA display, a 40GB, 5400rpm hard drive, a 16/10/24/8-speed CD-RW/DVD-ROM optical drive, and an Intel 802.11b adaptor, making this a true Centrino laptop, weighing in at just 2.2kg with a thickness of 2.7cm. For weight and size comparisons, the Aluminium 15-inch Powerbook is 2.5kg and 2.8cm, the 12-inch G4 iBook is 2.2kg and 3.42cm, while on the Mobile Pentium 4 front, the Millennium Music laptop PC reviewed in September's SOS is 4.4cm thick and weighs 4.4kg — exactly double the weight of the iBook and T40.
The T40 brims with clever IBM technologies, but the highlight for most will be the battery life: in true Centrino style, the standard lithium-ion (or Li-ion for short) battery offers around four to five hours of battery life, with the brightness set to a usable 50 percent, and the processor performance adjusted to its second-highest setting — expect around three to four hours with maximum brightness and processor settings. This is great, of course, but IBM also offer a high-capacity Li-ion that comes as standard with higher-end T40 models; and although this protrudes about thumb-depth over three quarters of the back panel, it offers a staggering eight to nine hours of battery life if you're being economical, and around five to six if you're not.
Most of the major laptop manufacturers are offering their own Centrino machines, such as the Maxdata model reviewed in last month's SOS.
While typical Mobile Pentium 4 and G4-based laptops can achieve similar levels of battery life if you carry multiple batteries around, this not only adds to the overall weight of your laptop bag, but soon becomes a hassle in terms of battery charging management. With its high-capacity battery, the T40 is one of the most desirable Centrino laptops available, despite more aesthetically attractive offerings from Samsung and Sony. And should you require even more battery life, you can remove the optical drive at the appropriate moment and replace it with an additional battery while the T40 is still running. This means you can run a laptop for the entire length of a transatlantic flight, without restarting. It also means you generally don't have to carry your laptop charger around, which can be quite a liberating feeling in itself!
I have to confess that I do sit in bed watching DVDs... I mean writing music with my laptop, and it's in these situations you really don't want your computer to get unpleasantly warm. Having tried this manoeuvre unsuccessfully with both the previous Titanium G4 Powerbooks and conventional Mobile Pentium 4-based notebooks, the T40 passed this 'Wherry laptop leg-roast' challenge with flying colours, although you'll have to take my word for this as shame prevents me from providing the necessary photographic evidence!
Getting back to the specifications, the T40's aforementioned 5400rpm drive allowed me to play a large piano instrument in Gigastudio with full 160-voice polyphony without breaking into a sweat, making it an ideal portable Gigastudio rig. In fact, most of the time I'm running Gigastudio with Cubase, or Gigastudio with Outlook, Mozilla Firebird, Word and Sibelius, and I'd never even dream I was trying to do something remotely clever in terms of my computing requirements. And of course, I'm not, if you consider the typical performance of a desktop system. But the combination of laptop performance with this level of power economy has never been seen before — and that's what impresses me. As an aside, a T40-owning friend surprised an Avid engineer by getting better performance than Avid-approved mobile systems on his T40 when running Xpress Pro!
No Smoke Without Firewire
The T40's two 32-bit Cardbus slots allow connectivity for audio hardware and Firewire cards, which, in fact, highlights my only possible criticism of the T40 from the audio and video user's perspective: the lack of a built-in Firewire port. Actually, for me, this wasn't such a big deal as for drives, I'd rather fit a bigger and faster internal drive if I needed the performance and capacity (see the Drive On box); and for audio hardware, I tend to prefer the Cardbus solutions for mobile use (see the Cardbus Audio box). However, I know that these are important considerations for some users, so while it sounds like a bland catch-all, this is one area where is really depends on how you plan to use your laptop in a given situation.
On the subject of connectivity, the T40 does, however, feature two USB 2.0 ports (thanks to the 855PM chip set), a modem, 10/100 Base-T Ethernet, a traditional parallel port, and S-Video and VGA ports for graphics. These latter two ports are supported by the internal ATI Radeon 7500 controller, connected via an AGP 4x interface, providing either mirroring or spanning; and while a DVI connector might have been nice, the T40's optional docking station provides such a port, along with the ability to house a half-length PCI card.
While this isn't a T40 review, if you hadn't guessed, I actually liked the laptop so much that I bought one. Considering the convenience and the fact it runs Nuendo, Cubase, Sibelius, Gigastudio and a host of plug-ins alongside Office, Visual Studio, Photoshop and other non-musical applications, the T40 has proven itself to be one of the most useful Windows machines I've owned. However, since I bought my T40, IBM have, of course, introduced the T41 range, which, for the most part, seems to offer the features found in the previous high-end T40 models at a more reasonable price point, including the 1400 x 1050 14-inch display, along with the fastest 1.7GHz Pentium-M chips and improved graphics chip sets with 128MB video memory. If you're looking for the ultimate portability and can live without a built-in optical drive, IBM's X series offers a light 1.64kg, less-than-an-inch-thick form factor featuring a 12-inch 1024 x 786, a Cardbus slot for your audio interface, a Firewire port, and a CF slot, which might be handy if you're a keen digital photographer.
The laptop in the hearts of most mobile musical geeks at the moment has to be IBM's new 1.5-inch-thick R50p, which features a gorgeous 15-inch 1600 x 1200 display, and the fastest 1.7GHz Pentium-M processor. It comes loaded with 512MB 333MHz RAM, upgradeable to 2GB (like the T40), an ATA100, 7200rpm, 60GB internal drive (see Drive On box), ATI's Mobility FireGL T2 graphics card with 128MB VRAM, a recordable DVD drive, gigabit Ethernet, an integrated 802.11a/b/g-compatible wireless card, and, oh, a battery life of nearly six hours! The only down side is the weight: 3.6kg, which is 400g or so heavier than Apple's 17-inch Powerbook. However, if you're talking a desktop replacement music machine, it's a case of game, set and match to the R50p. Rather a shame that it currently retails for about 4000 dollars in the US before sales tax.
IBM aren't the only computer manufacturer producing Centrino-based laptops, and other mainstream companies such as Samsung, Sony, HP and Toshiba also offer tempting products. However, IBM seem to offer the best battery lives with their extended batteries, and I personally have had good experiences with their machines.
Drive On
Until now, most laptop hard drives have offered lower spindle speeds and hence lower data transfer rates than those commonly used in desktop PCs, but new models such as the Travelstar E7K60 now boast a fast 7200rpm rotation speed.
Although the IBM T40 laptop mentioned in this article features a fast (for a laptop) 5400rpm drive, for those who require the ultimate mobile performance, it's worth mentioning that Hitachi Global Storage Technologies (HGST) are now offering 7200rpm Travelstar drives in up to 60GB capacities for laptop users. For those who like to know these things, HGST (www.hgst.com) was formed in 2003 when IBM and Hitachi merged their respective storage divisions, and the company now handles all of IBM's previous hard drive products, such as the Deskstar line.
The E7K60 Travelstar drive in question can be yours for $290, features low power consumption (with minimum heat), and is designed for intensive, always-on applications such as blade servers — two factors that make it more than suitable for audio (and video) work. You can find out more information about these drives at www.hgst.com/hdd/travel/tre7k60.htm, including white papers and purchasing information. A consumer-orientated 7K60 model is also available, which is slightly cheaper and isn't designed for 'always-on' performance, and this is the drive that laptop manufacturers such as IBM supply with machines such as the T41 and R50p.
Laptop Bake-off
If the proof of the pudding is in the eating, the proof of the laptop for musicians is surely in how much DSP power it provides for native-based applications, so I decided to run a few tests to see just how two T40 models stacked up against Apple's 17-inch Powerbook and a conventional Mobile Pentium 4-based laptop. In terms of audio hardware, I used the same Echo Indigo PCMCIA card on every system (see Laptop Audio box), although I also tried using the internal headphone output on the 17-inch Powerbook, which actually gave me exactly the same results in terms of CPU performance.
Of the two T40 models I used, one was a T40p with a 1.6GHz Pentium-M with 512MB RAM and ATI Mobility FireGL 9000 graphics with 64MB RAM, and the other was a standard T40 with a 1.3GHz Pentium-M and 768MB RAM, as described in the last section. The 17-inch Powerbook in question was the latest generation 1.33GHz G4 model with 1GB RAM and ATI Mobility Radeon 9600 graphics with 64MB RAM. And, finally, the Mobile Pentium 4 laptop used was a Compaq Evo N800w with a 2.2GHz Mobile Pentium 4, 1GB RAM, and also featured an ATI FireGL 9000 graphics chip set with 64MB RAM.
Figure 1: This graph shows the results from the test described in the main text. The solid colour shows the number of Reverb A plug-ins that could be run until the audio started failing, while the lighter region shows the number of plug-ins before the processor actually maxed out.
Conducting a fair performance test across multiple platforms is difficult, so I tried to come up with a situation that was relevant, simple, and as fair as possible. Using the latest version of Cubase SX 2, I created a test Project to see how many Reverb A plug-ins could be used, with a single A1 virtual synth rather than an audio file used as the audio source in order to keep the load on the computer focussed on the processing and avoid factoring in the varying overheads of hard disks and their associated controllers. The reverb plug-ins were placed as inserts on FX Channel Tracks rather than inserts on the A1 Channel itself, in order to keep the environment as consistent as possible when scaling the test beyond the eight insert effects allowed per Channel. Finally, all the gain controls (including the sends) were kept at 0dB, except the Master fader, which was set so there was no audible distortion.
I'll resist the urge to use some colourful metaphors to describe the results of the tests because, as you can see by the graph in Figure 1, overleaf, the outcome is easy to evaluate. Centrino-powered laptops are clearly as powerful as their Mobile Pentium 4 counterparts, with the 1.3GHz model offering the same level of performance as the 2.2GHz Mobile Pentium-4 system. And while the Centrino is admittedly a little more expensive than the Mobile Pentium 4, it offers the same performance with three or four times the battery life, and in a lighter, smaller form factor that doesn't get anywhere near as hot. After I ran the test, it would have actually been painful to touch the bottom of the N800w for more than a second, while the T40 remained casually warm.
Perhaps the biggest surprise was the relative performance of the 17-inch Powerbook. While it's fairly well-known that the G4's performance has been falling behind the competition, if you consider how much more you'll pay for this model over the Windows-based systems, and the fact that this is the highest-performing portable Mac money can buy, these facts would make me consider purchasing a Mac laptop only if I absolutely had to work on a Mac.
An interesting point about the Mac test was that even when the audio was breaking up, the actual responsiveness of the system, in terms of the user interface, wasn't impaired — something that could definitely not be said of the Windows-based systems. This is fairly easy to explain: Mac OS X's Quartz Extreme technology offloads a large proportion of its Aqua user interface graphics processing to the graphics card, so its performance is constant no matter the load on the system's main CPU. In some ways this fact reflects poorly on the G4, since the Intel processors achieve more DSP while running the bulk of the user interface as well, but it does reflect well on the architecture of OS X itself for processor-intensive media applications. Intel and AMD users might expect to see these kinds of technologies in Microsoft's next-generation Windows operating system, Longhorn, although we may not see this until 2005 or 2006.
4-gone Conclusion
Centrino-based laptops are powerful enough for digital media applications, although it's worth mentioning that Intel still have other solutions for mobile users in their Mobile Pentium 4 product line. While Centrino technology shows the ultimate direction for Intel's mobile strategy, considering the revised Dothan Pentium-M chip due next year, Intel are still continuing to improve their Mobile Pentium 4 chip line, with a recent revision including 533MHz front side busses, as opposed to the 400MHz variety used in previous Mobile Pentium 4 and Pentium-M designs.
These new Mobile Pentium 4 processors are derived from the Pentium 4 processors used in desktop computers, and although Intel offer a range of clock speeds from 2.4GHz to 3.06GHz in their mobile offerings, they omit the Hyperthreading technology, presumably to allow for cooler and more economical operation. The processors feature a 512k L2 cache, and when used with Intel's 852PM and 852GME chip sets, they can scale down to 1.6GHz for power conservation.
For those who require the most processing power available in a portable system — portable rather than mobile — a Mobile Pentium 4 system might be worth considering, especially given that it will be cheaper than a similarly equipped 1.7GHz Pentium-M system. Budget permitting, however, the benefits of the Centrino technology would lead me in that direction every time.
Left, Right & Centrino
With Centrino, Intel have finally liberated Windows-based laptop manufacturers from the burden of bulky, hot and battery-intensive technology; and forgetting the Windows operating system for a moment, it's hard to see who wouldn't want a powerful, cool and long-lasting laptop. Aside from aesthetics, the only two advantages that remain for Apple's range of laptops, in my opinion, is that they all have a built-in low-latency audio system and a Firewire port as standard, saving you from having to purchase an additional converter such as the Echo Indigo or, indeed, a Firewire card. This is obviously a big advantage for a musician, although if you need more than a single stereo input and output, you'll have to buy an additional converter anyway. And while some Centrino-based laptops do feature Firewire connectivity (the T40 aside), all feature USB 2 ports, and we're already starting to see the emergence of USB 2 audio hardware from companies such as Edirol.
Technology rarely stands still in this world, and at recent Intel Developer Forum events, the company have already announced Sonoma, the next generation of Centrino technology. Sonoma is based on Dothan, a revision of the Pentium-M processor due in the second half of 2004 that will feature a 2MB on-chip cache and over twice the performance of the current high-end 1.7GHz Pentium-M. Sonoma also features Alviso, a new motherboard chip set that will provide enhanced graphics and support for Serial ATA devices, and Express Card, which is based on PCI Express (an Intel development of the current PCI buss) to provide thinner and lighter expansion cards.
Of specific interest to mobile musicians is that the code-name-crazy Sonoma will also implement Azalia, Intel's next-generation PC audio technology, which will offer Dolby 7.1 playback and consume around the same power as current AC97-based laptop audio systems. Azalia should also allow for an overall improvement in the performance of a laptop's built-in audio capabilities, which should make it possible to work from the built-in headphone socket with minimal latency as Powerbook users can right now.
Until these technologies become available, I'm in no doubt that from a technical perspective, the most suitable laptops for the demands of mobile musicians are powered by Intel's Centrino technology. I'm excited to see what Apple do with their next range of Powerbooks, of course; but for now, when I leave the house, it's an IBM T40 that will be my music-making companion because in terms of performance and mobility, nothing else comes close.
Z