head touch f.d ?

[rahulkothari]

does the head of the f.d. touch its surface ? i think the answer is NO. but then, if it doesnt touch then wat do u mean by low-level formatting .... dividing physically into tracks and sectors.

i have read abt this low-high level formatting but never got the grip of it. http://www.PCGuide.com/ubb/frown.gif i mean wat it is practically ? ofcourse it doesnt "scratch" tracks and sectors !!!


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An eye for an eye makes the whole world blind.
-Mahatma Gandhi

[mjc]

By fd are you talking about the hard drive (sometimes called fixed disk) or floppy disk?

The heads of a hard drive never touch the surface, if they did it would be all over, the drive would be finished.

The floppy disk, yes it does......

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mjc
Links list:Computer Links (http://www.dreamwater.org/tech/mjc/index.htm)

Celts are the men that heaven made mad, For all their battles are merry and their songs are all sad.

[rahulkothari]

thx mjc. i meant floppy disk.

and the question:- if heads touch, that means the tracks and sectors are physically scratched, right ?

... i have never seen the platter of a hard disk, does it also have those small concentric circles as flopy disks coz in this case the head doesnt touch .... confused http://www.PCGuide.com/ubb/mad.gif http://www.PCGuide.com/ubb/rolleyes.gif http://www.PCGuide.com/ubb/tongue.gif

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An eye for an eye makes the whole world blind.
-Mahatma Gandhi

[mjc]

No, they aren't physically etched into the surface, but a floppy is read/written much like an audio cassette, the surface is very similar.

The platter of a hard drive is mirror polished.

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mjc
Links list:Computer Links (http://www.dreamwater.org/tech/mjc/index.htm)

Celts are the men that heaven made mad, For all their battles are merry and their songs are all sad.

[YODA74]

http://www.microscopy-uk.org.uk/mag/art98/hdrive.html
this has some pretty good info

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Death has come to our windows.

-- Jeremiah 9:21
(undoubtedly a Biblical reference to a Microsoft product!)

YODA74@windows-sucks.com

[rahulkothari]

thx yoda. cool link. it helped.

so the sectors and tracks r divided by some sorta magnetic head , not directly etched, its like making designs in sand by blowin air over sand instead of doing it with fingers ... , right ?

now is a CD or DVD too divided into tracks and sectors ... i suppose CD does have tracks ... i saw them with naked eyez. http://www.PCGuide.com/ubb/eek.gif http://www.PCGuide.com/ubb/eek.gif http://www.PCGuide.com/ubb/eek.gif

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An eye for an eye makes the whole world blind.
-Mahatma Gandhi

[This message has been edited by rahulkothari (edited 03-31-2002).]

[geebee76]

Hi rahulkothari, you are getting the idea.

As you have already stated the data on a Hard Disk is laid out on concentric tracks. Each of these tracks consist of sectors, which in turn hold the data and other information.
This data is held as minute magnetic fields on the disk.

The data is written to the Hard Disk with the use of electromagnetic heads, which change the direction of the magnetic field from N to S or
S to N. The data is read back from the disk by sensing these
magnetic fields. (Read about Flux Reversals and Encoding methods if you wish to fully understand this process)

Read through the section on Hard Disk Drives (http://www.pcguide.com/ref/hdd/index.htm) from the PC Guide main site for a fuller and more accurate description.

CD's are different altogether, they only have one spiral track and as you are probably aware, the data is read with the use of a laser. The writting of data to the disk is dependent on which type of media you are using eg: CD-ROM, CD-R or CD-RW etc. There are many different encoding
methods used for reading and writing to these disks. Have a look at The PC Guide section on CD-ROM Drives (http://www.pcguide.com/ref/cd/index.htm) or the CDRFAQ (http://www.cdrfaq.org/faq.html)

http://www.PCGuide.com/ubb/smile.gif

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[This message has been edited by geebee76 (edited 03-31-2002).]

[rahulkothari]

"The read/write head assemblies are spring-loaded--using the spring steel of the head arms--which causes the sliders to press against the platters when the disk is stationary. (This is done to ensure that the heads don't drift away from the platters; maintaining an exact floating height is essential for correct operation.) When the disk spins up to operating speed, the high speed causes air to flow under the sliders and lift them off the surface of the disk--the same principle of lift that operates on aircraft wings and enables them to fly."


thx everyone for the hlp. the above stats were picked from pcguide.com
here its mentioned the sliders actually touch when the disk is stationary. and when it rotates they lift off ... so dont they scratch for a while when the disk starts rotating ... i mean they r not immediately lifted off, it takes atleast some milliseconds, right ?

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regarding CDROM geebee said it has spiral tracks like phonograph, but then if it has spiral tracks then how can v count them coz i read here http://www.cdrfaq.org/faq02.html#S2-24 (2-24) that a disk has 99 tracks. http://www.PCGuide.com/ubb/tongue.gif

certainly geebee isnt wrong, but then i dont understand the "99" thing.

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An eye for an eye makes the whole world blind.
-Mahatma Gandhi

[geebee76]

Hi rahulkothari,
I am not up-to-date on the latest technologies but I believe that the quote you mentioned about the head resting on the disk is refering to a designated landing zone which, would typically be a track that doesn't contain data.

I haven't read the entire section on CD's but I think the "99" tracks is refering to the maximum number of music or data tracks that can be recorded to a CD-R using the Track at Once method. These different "tracks" would still be recorded onto the same single spiral track, just at different times and different locations.

http://www.PCGuide.com/ubb/smile.gif

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You are making progress if each mistake is a new one!

Sig from Here (http://www.oneliners-and-proverbs.com/)

geebee76@hotmail.com

[rahulkothari]

even if the track doesnt contain data then also , some amt of ferrite coating will wear off as the head actually touches it when the hdd isnt in motion and lifts off immediately when in motion.

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An eye for an eye makes the whole world blind.
-Mahatma Gandhi