Week 2: Clear- Hardware: How a drive Writes and Reads Bits on a Disk

Reading and Writing Bits on a Disk:


In the book, How Computers work, there was a small area explaining how a PC reads and writes on disks (Hard Drive or a CD).

Image: Chris Sharp / FreeDigitalPhotos.net  http://www.freedigitalphotos.net/images/view_photog.php?photogid=584

Details: http://www.freedigitalphotos.net/images/help/acknowledgement/index.php?photogname=Chris%20Sharp&photogid=584

Steps Involved:


1. A blank disc comes with magnetic iron particles randomly placed over the entire disk. In order to write on the disc, an iron core with a coil pulses electricity so that it arranges these iron particles into order.

2. The order is arranged into a language called Binary which is made of 1's and 0's which also stand for north and south (the polarities of the iron particles). 

3. After it is written on the disc, the coil does not pulse electricity through the disc, but acts in the opposite way. It runs over the disc sensing a change in polarities. This change in polarities is decoded into the binary data.