1. Microprocessor and Assembly Language
Lecture-12-Multiplication and Division Instructions
Muhammad Hafeez
Department of Computer Science
GC University Lahore

2. Today’s Agenda Signed and Unsigned Multiplication
Signed and Unsigned Division

3. Multiplication Instructions
The process of multiplication is different for signed and unsigned numbers
Example:
Take 2 number
and
As unsigned numbers are 255 and 128
Product = 32640
As signed numbers are -128 and -1
Product = 128

4. Instruction for Signed and Unsigned Multiplication
MUL is used for Unsigned multiplication
IMUL is used for singed multiplication
Syntax is:
MUL Source
IMUL Source

5. Byte Form For byte x byte, one operand must be in source
Second operand is assumed in AL register
16-bit result is stored in AX register
The source must be a register or a memory location, constants are not allowed

6. Word Form For Word multiplication one number must be in source
Second number is assumed in AX register
32-bit result is stored in DX:AX
DX holds the Most significant bits
AX holds the Least Significant bits

7. Examples:
Translate A= 5 x A – 12 X B using IMUL Instruction.

8. Examples:

9. Division Instructions
DIV instruction is used for unsigned division
Syntax:
DIV Divisor
IDIV instruction is used for signed division
Syntax
IDIV Divisor

10. Division Instructions
Byte Form:
The divisor is 8-bit register or memory location
The dividend is 16-bit that is assumed to be in AX
After division
AL = Quotient
AH = Remainder
Divisor must not be a constant

11. Division Instructions
Word Form:
The divisor is 16-bit register or memory location
The dividend is 32-bit that is assumed to be in DX:AX
After division
AX = Quotient
DX = Remainder
Execution of DIV or IDIV could result in divide overflow

12. Decimal Input/ Output In memory everything is represented in binary.
Decimal Input and Output could be done through a program

13. Decimal Input/ Output In memory everything is represented in binary.
Decimal Input and Output could be done through a program

14. Decimal Output

15. Decimal Output

16. Test Program

17. Decimal Input
Convert a string of ASCII digits to the binary representation of a decimal equivalent

18. Decimal Input

19. Decimal Input