grabbed a piece of paper from her desk and a pen. Quickly she scrawled back:

Dear Headmistress McGonagall,

I am very excited to receive this information and attend Hogwarts.

Sincerely,

Hermione Granger

She rolled the piece of paper up and slipped it into the leather tube attached to the owl’s leg. “Please be sure that Headmistress McGonagall receives this, thank you,” she said and stepped back from the owl who clicked in reply. With a resounding woosh, the owl was out the open window again and flying over the rows of houses. Hermione starred after it in wonder and was curious as to how quickly a reply would arrive. Shrugging, Hermione gathered up the letter and supply list and bounded downstairs to show her mum and dad.

Her parents were seated quietly in thesystem external to the storage device.
The heads are supported in close proximity to the media by a head positioning assembly capable of operating in two distinct modes: track seeking and track following. During track seeking, the heads are moved transversely to the tracks from a current data track to a desired or target track in response to a read or write request from the external system. Track following is the function of maintaining a head in alignment with a track while reading, writing, or merely idling.
In most storage devices, movement of the head positioning assembly is controlled by a closed loop servo system comprising a combination of servo electronics and microcode. Closed loop systems utilize position information obtained from the surface of the storage medium as feedback to