Binary

GB(decimal) vs. GiB(binary)
Gigabyte vs. Gibibyte

  Proposed standard.
  For the most part still not practiced.

Binary - usually used with memory addressing.
  Large
    Terabyte (TiB tebibyte) - 1 * 2^40
    Gigabyte (GiB gibibyte) - 1 * 2^30 = 1073741824
      = 1.074 GB or 1.074 * 10^9 bytes

    Megabyte (MiB mebibyte) - 1 * 2^20 = 1048576
    Kilobyte (KiB kibibyte) - 1 * 2^10 =    1024

    Other powers of 2
    1*2^16 = 65536 (memory range of many early cpus)
    1*2^8 = 256  (byte)
    1*2^4 = 16   (nibble)
    1*2^2 = 4
    1*2^1 = 2
    1*2^0 = 1

    Binary math.

    32 bit address line = 2^2 * 2^30 or 4 * 1 GiB or 4GiB


Example
  If cpu capable of address 1Mi byte memory, and memory chips come in 64Ki byte
  units, how many memory chips are needed?

  1MiB = 1*2^20 bytes,  64KiB = 64*1Ki = 2^6*2^10 = 2^16 bytes/chip

  (2^20 bytes)/(2^16 bytes/chip) = 2^(20-16) = 2^4 chips = 16 chips.

  How many address lines are on each chip?  16

  A decoder will be needed to select the appropriate chip, how
  many select lines are needed?  2^4 = 16  or  4 lines