9. A. List two advantages of magnetic media over optical media.

Magnetic disks, with the exception of floppy disks, can be written and read faster than optical disks. Most hard disk drives offer greater capacity than any currently available optical device. And usually the writable of magnetic disks is unlimited.

b. Fill in the following chart matching the type of media with its storage capacity. The types of media to choose from are Jaz disk, Zip disk, hard disk drive, high-density floppy disk, and double density floppy disk.

Type of Media	Storage Capacity
double density floppy disk	720 KB
high-density floppy disk	1.44 MB
Zip disk	100 MB or 250 MB
Jaz disk 1	1 GB or 2 GB
hard disk drive	20-80 GB

c. Consider that magnetic media is read by an electromagnet. How does the read/write head discern and transfer data from the magnetic media to the system?

Before data is stored, the particles on the surface of the disk are scattered in random patterns. The disk drives red-write head magnetizes the particles, and orients them in either a positive or negative direction. These patterns of magnetized particles represent 0 and 1 bits.

10. A. Define Moore's Law.

The observation made in 1965 by Gordon Moore, co-founder of Intel, which the number of transistors per square inch on integrated circuits had doubled every year since the integrated circuit was invented. Moore predicted that this trend would continue for the foreseeable future. In subsequent years, the pace slowed down a bit, but data density has doubled approximately every 18 months, and this is the current definition of Moore's Law, which Moore himself has blessed. Most experts, including Moore himself, expect Moore's Law to hold for at least another two decades.

b. List two extrapolations of Moore's Law that are discussed in the course materials.

Processing power (speed) doubles every 12-18 months. Storage capacity of RAM doubles every 12-18 months.

c. How can Moore's Law and the extrapolations from Moore's Law assist a consumer in purchasing a computer?

User expect to pay for a computer today that is twice as powerful as the computer that is now 18 months old approximately the same amount of money paid for the old computer.

d. Define Parkinson's Law of Data.

Parkinson's law of data states that data expands to fill the space available.

e. Using Parkinson's Law, what projection can be made regarding memory and hard disk usage?

f. How can Parkinson's Law assist a consumer in purchasing software or components for a computer?

11. A. List two advantages of optical media over magnetic media.

Optical media are more durable. They are not ruined by dust or moisture, nor are they vulnerable to electrical damage. Optical media's MTBF rating ranges between 30 and 300 years, while magnetic media utilize magnetic properties that have a MTBF of about 37 years.

Optical media are less expensive per MB than magnetic disks.

b. Fill in the following chart. The types of media to choose from are CD-R, CD-RW, CD-ROM, and DVD-ROM.

Type of Media	Storage Capacity	Number of Times It Can Be Written To
CD-ROM	650-700 MB	0
CD-R	650-700 MB	Write once
CD-RW	650-700 MB	Many
DVD-ROM (SLSS)	4.7 GB	Read only

c. Consider that optical media is read by a laser. How does the laser discern and transfer data from the optical media to the system? In the optic readable CD-ROM, the data storage consists of millions of indentations burnt into the lacquer coated, light reflecting silver surface. The burnt dents reflect less light than the shiny surface. A weak laser beam is sent to the disk through a two-way mirror and the sensor registers the difference in light reflection from the burnt and shiny areas as zeros and ones.

d. Consider that a DVD and a CD are the same size. List two reasons a DVD holds more information than a CD. First, DVDs have narrower tracks, so they can squeeze more tracks onto the same size disk. Both CDs and DVDs are read using light from a laser. But, the CD laser is red, while the DVD laser is blue. Red light has a longer wavelength than a blue light. The blue laser is thus able to produce a smaller beam, allowing it to focus on the tinier tracks of the DVD. The second way that DVDs achieve increased capacity over CDs is by using multiple layers of tracks. The blue laser is not only narrower, but also more powerful. Its beams can penetrate the plastic and focus at different depths.