Question

Describe the following disk concepts or compo- nents.
a. Platter and recording surface. b. Track. c. Cylinder. d. Read/write head.
e. Access-arm mechanism.

Answer 1

a. Platter and Recording surface:

A platter is a flat, round aluminum or plastic disk coated with a coating that can be magnetized on a bit-by-bit basis. Obviously, a platter has two recording surfaces and typically both are used for recording data.

• In certain devices only one of the two surfaces of certain platters may be used.

b. Track:

A track is a circular pattern on a recording surface on which data is stored on a bit-by-bit basis.

• A recording surface has many tracks arranged in concentric circles.

c. Cylinder:

A cylinder is a set of tracks, one from each recording surface.

• From a top view, they appear to be lined-up one directly over the other.

d. Read/write head:

The read/write head is the portion of the disk drive mechanism that actually transfers data on and off the disk.

• In most devices, there is one read/write head per recording surface.

e. Access-arm mechanism:

The access arm mechanism contains all of the disk drive’s Read/write heads, lined up one exactly above the other.

• When it moves and then stops in a new position, it is capable of accessing each track of a single cylinder, one at-a-time.