5.2 Numbering systems Flashcards
the most common numbering systems are
decimal - base10
binary - base2
octal - base8
hexadecimal - base16
decimal (base10) number system has its origin
from counting on the fingers
digit comes from the Latin word digitus which means finger
base is the number of different digits including zero in the number system e.g.
octal or base8 = 0 to 7
hexadecimal or base 16 = 0 to F
the value of the largest digit of a numbering system is one less than the base
the value of the smallest digit in the number system is zero
the standard shorthand form of writing numbers is known as the positional notation
.
the most common numbering system used in everyday life
is decimal.
the digit at the far right is called the (LSD) least significant digit
the digit at the far left is called the (MSD) most significant digit
octal system is a shorthand method of
representing three-bit binary words
binary coded decimal
.
the simplest number system employing positional notation is
binary.
has a base of 2
uses just two digits 1 and 0
the value of the largest digit of a numbering system is one less than the base. For example, in a binary system (base 2), the largest digit is 1.
.
The value of the smallest digit of a numbering system is
zero
Gray code is also known as
reflective binary code
The binary number system is used in digital electronics because the two basic conditions of electricity, ‘ON’ and ‘OFF’, can be represented by the two digits of the binary number system
ON’, it represents the digit 1, and when it is ‘OFF’, it represents the digit 0.
417 in the decimal system. As it is converted digit-by-digit, the first digit is the 4, which in binary is 0100. Second, the 1 is a binary 0001. Finally, the 7 is 0111
That makes the full number 417 in BCD equal to 0100 0001 0111 2
when is gray code useful
when rapidly changing values could result in errors due to hardware and interfacing constraints.
Gray codes are used in rotary and optical encoders, Karnaugh maps, and error detection
The hamming distance (a metric for comparing two binary data strings) of two neighbouring Gray codes is always
1
first Gray code and last Gray code also has hamming distance is always
1 so it is also called cyclic codes
In aircraft, where altimeters are normally mechanical, an encoding disk synced to the dials may produce a type of Gray code output
called the Gillham code to send to the transponder for processing
Gray code sequences must be converted to what if they are used in mathematical computations or for displays
binary or binary coded decimal (BCD)
2 to the power of 0 =
1
2 to the power of 1=
2
converting decimal to binary step 1.
divide 100 by 2
use quotient obtained in this step as the dividend for the next step
repeat the process until quotient becomes 0
binary equivalent is obtained by reading the remainders from bottom to top as shown below.
Dividend Remainder
100 ÷ 2 = 50 0
50 ÷ 2 = 25 0
25 ÷ 2 = 12 1
12 ÷ 2 = 6 0
6 ÷ 2 = 3 0
3 ÷ 2 = 1 1
1 ÷ 2 = 0 1
answer is = 1100100
in converting decimals to binary what is considered the most significant bit (MSB)
The first remainder obtained (at the bottom)
in converting decimals to binary what is considered the least significant bit (LSB)
The last remainder (at the top)