LeiOn
06-06-2001, 03:35 PM
Hi
I study a course on computer technology, and one of our books is really getting on my nerve, it's full of errors and misspellings. I've managed to decode most of it using other books and the internet, but one part on hard disk construction is still too confusing. Here's what it says:
When the hard disk starts reading from a sector, it must synchronize it's internal clock (a VCO - voltage controlled oscillator). I believe it must be done because data is transferred faster when the r/w-head is positioned near the hub, right?
Further, each sector is divided into two fields, the adress and the data field, separated by some unused space. The HDD must first synchronize it's internal clock using a series of ones (or zeros) found first in the sector-field. Then upon entering the data-field, it must again synchronize, but this time an external clock, before comencing the read-operation.
My questions are:
Is above information correct in the first place?
What is this external clock?
Why using an external clock, isn't the data buffered in the device controller on the HDD anyway, what's the use of having two VCOs if they're never used concurrently and always run on the same frequency.
What does unused space mean, that it's not magnetized or what?
Thanks for reading this far
http://www.PCGuide.com/ubb/tongue.gifHenrik LeiOn, computer tech student, Sweden
I study a course on computer technology, and one of our books is really getting on my nerve, it's full of errors and misspellings. I've managed to decode most of it using other books and the internet, but one part on hard disk construction is still too confusing. Here's what it says:
When the hard disk starts reading from a sector, it must synchronize it's internal clock (a VCO - voltage controlled oscillator). I believe it must be done because data is transferred faster when the r/w-head is positioned near the hub, right?
Further, each sector is divided into two fields, the adress and the data field, separated by some unused space. The HDD must first synchronize it's internal clock using a series of ones (or zeros) found first in the sector-field. Then upon entering the data-field, it must again synchronize, but this time an external clock, before comencing the read-operation.
My questions are:
Is above information correct in the first place?
What is this external clock?
Why using an external clock, isn't the data buffered in the device controller on the HDD anyway, what's the use of having two VCOs if they're never used concurrently and always run on the same frequency.
What does unused space mean, that it's not magnetized or what?
Thanks for reading this far
http://www.PCGuide.com/ubb/tongue.gifHenrik LeiOn, computer tech student, Sweden