This content covers second unit COMPUTER ARCHITECTURE AND ORGANIZATION framed as per syllabus of Anna University 2017 Regulation.. This upload covers unsigned and signed division algorithms. Under unsigned division, restoring and non-restoring algorithms are covered with hardware diagrams,flowchart and example.

1. Computer
Architecture & organization
ALU
S.CIYAMALA KUSHBU
ASSISTANT PROFESSOR/ECE

2. Division
Restoring algorithm Non-Restoring algorithm

3. DIVISION
 Implemented by successive subtractions
 Result must verify the equality
Dividend = Multiplier× Quotient + Remainder
PAPER PENCIL BASED UNSIGNED BINARY DIVISION

4. UNSIGNED DIVISION
(RESTORING ALGORITHM-Version-1)
64 bit Divisor, 64 bit ALU unit,64 bit Remainder and 32 bit
Quotient

5. MSB=1MSB=0

6. OBSERVATION IN FIRST VERSION
 ½ bits in divisor is zero
 64 bit adder is wasted

7. REFINED VERSION

8. NON-RESTORING
ALGORITHM-
FLOWCHART

10. 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)
------------------- --------------------

11. 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

12. 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