CompuServe Messages

Joanne, I limited my discussion to "consumer" drives. For clarification, I consider a consumer drive to be one that's in the $2,000 or less ballpark. While I have no idea of the price of the Magic…I suspect it's not in this range. The number of headsis really of no concern in read speed discussions unless the drive is capable ofreading more than one head at a time. The rpm and sectors per track are of concern. A drive running at 6300 rpm is doing 105 rps. At 85 sectors per track (presuming they're 512 byte physical sectors) that's equal to 4.36 Meg/Second max sustained rate. Close…but still short of the 5 Meg/Second rate. And, of course, that speed presumes 0 time to switch heads or step to another track. If the sectors are properly laid out in a cylinder, the head switch time can be essentially 0. But the step rate can be 'significant'. Taking your Magic drive at 6300 rpm/85 sectors per track/15 heads and presuming a 0 head to head switch time, but a 10ms track to track step/settle and find sector 0 time…in order to read 5 meg, it must read 10,240 sectors. Your drive has 1275 sectors/cylinder. So the 5 meg is contained in slightly more than 8 cylinders. That's at least 8 track to track steps required or 80ms added to the actual read time. Since your drive reads 8925 sectors per second (105 x 85) the actual read time for 10240 sectors is 1.147 seconds. Add the 80ms step time and it will take 1.227 seconds to read the 5 meg presuming it's laid out properly. And that is an effective rate of 4.075 Meg/Second…about 20% short of 5 meg per second. Don