Computer Architecture & organization ALU S.CIYAMALA KUSHBU ASSISTANT PROFESSOR/ECE
Division Restoring algorithm Non-Restoring algorithm
DIVISION  Implemented by successive subtractions  Result must verify the equality Dividend = Multiplier× Quotient + Remainder PAPER PENCIL BASED UNSIGNED BINARY DIVISION
UNSIGNED DIVISION (RESTORING ALGORITHM-Version-1) 64 bit Divisor, 64 bit ALU unit,64 bit Remainder and 32 bit Quotient
MSB=1MSB=0
OBSERVATION IN FIRST VERSION  ½ bits in divisor is zero  64 bit adder is wasted
REFINED VERSION
NON-RESTORING ALGORITHM- FLOWCHART
CALCULATION  M  00011  -M MEANS 2’S COMPLEMENT OF +M 00011 11100 (1’S) -M11101 (2’S) A-M=A+(-M) 00001 (A) 00001 (A) 11101 (-M) 00011 (M) ------------------- ----------------- 11110 A+(-M) 11110 (A-M) ------------------- --------------------
Advantage :  A test subtraction is not required  The sign bit determines whether an addition or subtraction is used. Disadvantage:  An extra bit must be maintained in the partial remainder to keep track of the sign
SIGNED DIVISION SIMPLEST SOLUITON:  Convert to positive and adjust the sign later CONVENTION:  Dividend and remainder have the same sign  Quotient is negative if signs disagree
UNSIGNED AND SIGNED BINARY DIVISION

UNSIGNED AND SIGNED BINARY DIVISION