1
Signed Binary Number
Z. Aliyazicioglu
Class #3
April 8, 2002
Introduction
•Signed binary numbers means that both
positive and negative numbers may be
represented.
•The most significant bit represents the sign.
•Three main signed binary number codes are
used.
–Sign magnitude
–2s complement
–1s complement
Signed Magnitude Codes
•The most significant bit position is 0 for
all positive values
•The most significant bit position is 1 for
all negative values
•The rest of the bits represent the
absolute value
Example:
Decimal Number Sign magnitude
+15 01111
+10 01010
+8 01000
+6 00100
+3 00011
+0 00000
-0 10000
-3 10011
-5 10101
-10 11010
-
15
11111
1’s Complement Code
•The most significant bit position is also used
to represent sign for 1’s complement
•1’s complement of binary number N defined
as (rn-1)-N.
–r is the based
–n is the number of digits
•1’s complement number is formed by
changing 1’s into 0’s and 0’s into 1’s.
Example:
Decimal Number 1’s complement
+15 01111
+10 01010
+8 01000
+6 00100
+3 00011
+0 00000
-0 11111
-3 11100
-5 11010
-10 10101
-15 10000
