Chapter 3 Data

• Binary

  Binary is used to represent data(images,sound,text) and in programs
• Denary

  The name of the number system we use every day.Also known as decimal or base 10.Its based on 10s because we have 10 fingers.
• Binary meaning

  name of the number system the computer uses
• What is binary?

  Binary only uses 0 and 1s
• Binary

  a number that uses two digits
• Bit

  a binary digit 0 or 1
• Nibble

  a group of 4 bits
• Byte

  a group of 8 bits
• Word

  a group of bytes(varies)
• Overflow meaning

  overflow occurs when two postive numbers are added together,and the answer needs more bits to represent it than are available.
• Negative numbers in binary

  The computer can not store a minus sign with each number

  Binary numbers which are just positive are called unsigned-they do not have a negative or positive sign.
• Signed magnitide

  If we have an 8-bit binary number we could just use 7 bits for the number and then the final bit for whether its negative or postive.
• Two main methods a computer uses to represent negative numbers

  -Sign magnitude

  -Two's complement
• What do both sign magnitude and two's complement use?

  Most significant bit(MSB)

  A sign bit value of 0 indicates that the number is positive.

  A sign bit value of 1 indicates that the number is negative.
• Hexadecimal

  Hex=only used as it is easier for humans to remeber and is more straight forward to convert into binary.