on 07/18/03 12:44 AM, Andrew Kershaw at [EMAIL PROTECTED] wrote: >> but I can't understand why a firewire or USB external 40gb HD, that comes in >> a cool case, runs at 7200rpm, comes with free software and cute accessories, >> etc, etc, is $20-30 less than: >> >> an internal HD for powerbooks that is 10gb lighter, (20 or 30 gb) has no >> bracket, just the HD itself, runs at 5400 rpm? could it be that they sell >> more external hard drives? >> [snip] > It's frustrating, isn't it? There are a bunch of reasons why those > drives are cheaper. For one thing, they are produced in much higher > volumes than fast laptop drives. Also, the technology is hardly new, > and 7200rpm drives are becoming pretty standard these days. So R&D > costs are minimal. > > Fast laptop hard drives require significant engineering expertise - > getting high capacities and fast throughput into an energy efficient, > small form factor drive is something that comes with high costs. > 5400rpm drives are rare, even for the rather lean laptop market. > That all means that to turn a profit (keep in mind, too, that laptop > component profit margins are traditionally higher than desktop > components'), component manufacturers have to price their products > yet higher.
Just compare the size/volume of a 3.5" internal drive for a desktop/tower machine (this is the type of drive inside the external case), and a 2.5" laptop drive. As an exercise, take the ratio of the diameters of the platters, 3.5/2.5 and square that find that the larger drive has twice the available surface area, so the laptop drive would have to pack in the information to roughly twice the density to break even with the larger drive. [Of course, that factor of two will be modified by how many platters each drive has, but this gives you a rough feel.] Furthermore, the mechanical parts will scale as volume (3.5/2.5 cubed). As you can see, the laptop drive has a much tougher technology task to come anywhere close to the desktop/external drive. And this doesn't include the fact that the laptop drive must be designed more carefully from a thermal and energy consumption standpoint. - Eric. -- Eric Strobel ([EMAIL PROTECTED]) ===================================================================== Design is an iterative process. The necessary number of iterations is one more than the number you have currently done. This is true at any point in time. ===================================================================== -- PowerBooks is sponsored by <http://lowendmac.com/> and... Small Dog Electronics http://www.smalldog.com | Enter To Win A | -- Canon PowerShot Digital Cameras start at $299 | Free iBook! | Support Low End Mac <http://lowendmac.com/lists/support.html> PowerBooks list info: <http://lowendmac.com/lists/powerbooks.shtml> --> AOL users, remove "mailto:"; Send list messages to: <mailto:[EMAIL PROTECTED]> To unsubscribe, email: <mailto:[EMAIL PROTECTED]> For digest mode, email: <mailto:[EMAIL PROTECTED]> Subscription questions: <mailto:[EMAIL PROTECTED]> Archive: <http://www.mail-archive.com/powerbooks%40mail.maclaunch.com/> Using a Mac? Free email & more at Applelinks! http://www.applelinks.com
