External Memory in Computer Organization Quiz

5 Questions

Contemporary read heads have a separate read head close to the write head, while traditional read heads do not.

Data are organized in a concentric set of rings called tracks, with each track having the same width as the head.

The direction of the magnetic field

Adjacent tracks are separated by gaps to minimize errors due to misalignment of the head and interference of magnetic fields.

Data are transferred to and from the disk in sectors, which can be fixed-length or variable length.

Study Notes

Types of external memory include magnetic disk, optical memory, and magnetic tape.

A magnetic disk consists of a circular platter made of non-magnetic material (substrate) coated with a magnetizable material.
Traditional substrates are made of aluminum or aluminum alloy, but recently glass substrates have been introduced.
Glass substrates offer several advantages, including: • Improved surface uniformity to increase reliability • Reduced surface defects to reduce read/write errors • Support for lower fly heights • Better stiffness to reduce disk dynamics • Better shock/damage resistance

Data is recorded and retrieved using a conductive coil called a head.
There may be a single read/write head or separate heads for each function.
During read/write operations, the head is stationary, while the platter rotates.
The write process involves: • Current flowing through the coil to produce a magnetic field • Pulses sent to the head • A magnetic pattern recorded on the surface below