13 - Numbering Systems

Question 1

How many bits as standard ASCII?

Answer 1

7 bits

Question 2

How many bits as extended ASCII?

Answer 2

8 bits or 1 Byte

Question 3

How many bits as Unicode?

Answer 3

16 bits or 2 bytes

Question 4

How many characters allows standard ASCII?

Answer 4

128 chars

Question 5

How many characters allows extended ASCII?

Answer 5

256 chars

Question 6

Name the common ASCII codes in mobile forensics for:

• numbers
• uppercase letters
• lowercase letters

Answer 6

• Codes 48-57 (0x30 - 0x39)
• Codes 65 - 90 (0x41 - 0x5A)
• Codes 97 - 122 (0x61 - 0x7A)

Question 7

Explain Unicode?

Answer 7

Unicode tables are divided into blocks. Uses 2 bytes to represent characters. Has incorporated ASCII characters into its table with the lead byte having the value 00. Example ASCII Character 41 is 0041 in Unicode.

Question 8

What is Reverse Nibble?

Answer 8

There are two nibbles in a byte. Half a byte is a nibble. Reverse nibbling swaps the position of each nibble. E.g: 98 becomes 89. This is a common value for searching in hexadecimal strings in mobile phones for the lead numbers of the ICCID.

Question 9

What does ASCII stand for?

Answer 9

American Standard Code for Information Interchange