LAMPS

[shaunywhite]

WHAT IS AN INDEX LAMP USED FOR ON A 5.25 FLOPPY DRIVE. WHY IS IT NOT USED TO GENERATE START OF TRACK MARKERS IN THE IBM PC?


Thanks

[tjaymadison]

My goof -- Deleted http://www.PCGuide.com/ubb/frown.gif
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"When I nod my head, hit it with the hammer."
-- (Moe, holding nail, to Curly, holding hammer)

[This message has been edited by tjaymadison (edited 04-29-2001).]

[tjaymadison]

PLEASE turn off your Caps Lock key -- it makes your posts very hard to read. BTW, is this a homework problem? http://www.PCGuide.com/ubb/wink.gif

The "index lamp" shines through the small, pencil-point "index hole" in a 5.25" diskette onto a sensor. While the media platter or "cookie" is rotating, the hole passes between the lamp and the sensor, generating a series of on-off pulses that are used as an RPM counter. The logic circuity in the drive electronics can compare this count to a specified reference value to determine whether the disk has reached the speed required for a successful read or write operation to occur.

Second question -- probably cost (too high) and/or response time (too slow). Magnetic "markers" written by formatting work fine for this.


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"When I nod my head, hit it with the hammer."
-- (Moe, holding nail, to Curly, holding hammer)

[shaunywhite]

First of all, i am posting this for a friend who does not have web access, and it was he who typed it. And no i dont tnink it is for any assignment, its just for general interest.

Anyway thanks for the answer.