Oh, Lee, when I read and try to understand, and then look up those terms from ATA 100 and ATA66 (in Germany ATA is a cleaning agent like Bon ami) and check on fire wires and Maxtor ( big gate? ) and SATA , and I do look up and try to make sense of your explanations, just because I am so overawed by what comes out of your brain, I nevertheless do still feel like the student in Goethe's "Faust" when , after a lecture by Mephisto he, being so naive, finally states: Mir wird von alledem so dumm, als ging mir ein M?hlrad im Kopf herum" ( all of this stuff confounds me so much as if a mill wheel were churning around in my head. - I shall soon ?- taste the two flavors of Firewire, and anticipate the No 2 will be the more flavorful. And I shall be wrestling with bits and bytes. And in doing so will have fits and fights. Thanks for your inputs. Marta
On Nov 3, 2005, at 11:55, Lee Larson wrote: > On Nov 2, 2005, at 9:29 PM, NPfield at aol.com wrote: > >> Lee, I'm using an iMac G4 (w flat panel display); the internal drive >> is the one that came with the Mac and the external drive is a Seagate >> 300GB Dual-Interface (no model number, apparently). > This is one of those things I played with, out of curiosity, a while > back. I wrote a program to do nothing but read bytes off a disk and > throw them away. Then I timed it on a large file. (I never did get > around to writing a program to time writing.) Here's what I found out. > > The iMac G4 models used two different Ultra ATA interfaces. They began > with Ultra ATA/66, which has a maximum transfer rate of 66 MB/s. Later > models moved to the Ultra ATA/100 which has a maximum transfer rate of > 100 MB/s. We can only dream of getting near the maximum data rate. I > have a tower G4 with Ultra ATA/100, and my unscientific tests with > large files never give over 38 MB/s. (This is with a Maxtor 200 GB? > 7200 RPM drive.) > > I assume your dual drive is Firewire and USB2. If you want speed, stay > away from USB2 because USB was designed to be a cheap serial interface > for things like mice, keyboards and still cameras. Since it's cheap > and ubiquitous on PCs, people began using it for hard drives.? > > Firewire was intended from the beginning to be a fast transfer method > for things like hard drives and video. It has a smart controller that > takes a lot of load off the processor, so the machine can continue > doing other things while large copies are taking place. (This is less > true of ATA and not true at all for USB.) There are two flavors of > Firewire out there, Firewire 1, which can transfer up to 400 Mb/s and > Firewire 2, which maxes out at 800 Mb/s. (Notice the small "b" for bit > rather than byte.) I suspect your iMac has Firewire 1. > > I have a 200 GB Western Digital 7200 RPM drive in an external Firewire > 2 compatible box. On the G4 tower at home, which has Firewire 1, it > maxes out at 35-40 MB/s. In my office, I have a dual G5 Firewire 2, > and the same drive transfers as much as 45 MB/s. I suspect the > limitation is the drive. > > I've played with timing the SATA in the dual G5 in my office, and it's > speed seems somewhere between 50 and 55 MB/s, but I've not taken the > time to do it properly because I just got the machine a month or so > ago. | The next meeting of the Louisville Computer Society will | be November 22 at Pitt Academy, 6010 Preston Highway. | The LCS Web page is <http://www.kymac.org>. | List posting address: <mailto:macgroup at erdos.math.louisville.edu> | List Web page: <http://erdos.math.louisville.edu/macgroup>
