Chapter Four: Representing Data

Question 1

What is the difference between using the ASCII set and the Unicode character set?

Answer 1

ASCII uses 7 bits so can provide 127 characters or symbols plus the null character (128 in total). Unicode uses 16 bits, providing over 65,000 possibilities, or 32 bits providing over four billion possibilities.

Question 2

What are the main factors affecting the size of the file needed to store an image?

Answer 2

The resolution is the number of the pixels per unit, for example, the number of pixels per inch. The more pixels per inch, the more data to be stored and the larger the file needed to store the image.

Question 3

How does sample rate affect the quality of the playback for an MP3 sound track?

Answer 3

At a low rate:
Very few samples are taken.
At a higher rate:
Many more samples are taken.

Question 4

How does a computer tell the difference between instructions and data?

Answer 4

The CPU cannot tell the difference between data and instructions and simply deals with what it finds according to what it expects to find.

Question 5

How are instructions stored in binary in a computer?

Answer 5

The accumulator is a special register in the CPU used to store the results of any calculations.