Unit 6 - Data Types

Question 1

What is the difference between ASCII and Unicode? (3)

Answer 1

• ASCII uses 7 bits to represent a character, whereas Unicode uses a varied number of bits.
• ASCII can represent 128 different characters, whereas Unicode allows for over 1 million different characters.
• ASCII only represents the English language, numbers, and some symbols, whereas Unicode can represent different languages, numbers, symbols, and emojis.

Question 2

Explain the two ways to represent a negative number in binary.

Answer 2

• Two’s Complement: invert all bits and add one. Can be used for arithmetic.
• Sign & Magnitude: the MSB changes to a sign bit where 0 and 1 mean positive and negative, respectively. Cannot be used for arithmetic.

Question 3

Explain what happens when a 9-bit number is represented using 8 bits.

Answer 3

• Overflow error: extra bits are discarded, leaving inaccurate values.

Question 4

Explain the ways to represent a fractional number in binary.

Answer 4

• Floating point: a binary number with a decimal point. The numbers on the right of the point are 2^n, the numbers on the left of the point are 2^-n
• Mantissa & Exponent: a binary number (mantissa) is multiplied by 2 to the power of another binary number (exponent).