The document provides instructions on the 'add' operation in assembly language within the University of Duhok's Computer Science Department. It explains the format for the 'add' instruction, notes the operand types, and gives examples for adding hexadecimal values using registers. It emphasizes that two memory operands cannot be included in one instruction and describes how immediate values are sign-extended.

1. ADD instructions
Part #1
University of Duhok,
Computer Science Dept.

2. ADD instruction
The ADD instruction has the following format:
ADD destination,source
The ADD instruction tells the CPU to add the source and the
destination operands and put the result in the destination.
Destination = Destination + Source
• The destination operand can be a register or a memory location.
• The source operand can be an immediate, a register, or a memory
location.
By: Jawaher A. Fadhil Computer Science Dept.

3. • Two memory operands cannot be used in one instruction.
• When an immediate value is used as an operand, it is sign-
extended to the length of the destination operand format.
ADD AL,1355H
ADD instruction
ADD [500],[502]
By: Jawaher A. Fadhil Computer Science Dept.

4. Example#1
To add two numbers such as 25H and 34H, each can be
moved to a register and then added together:
MOV AL,25h
MOV BL,34h
ADD AL,BL AL= 25H +34H
AL=59H BL=34H
By: Jawaher A. Fadhil Computer Science Dept.

5. Example#2
Write the Assembly language instructions to add the values
6BH and A8H. Place the result in register AX?
MOV AX,0000
MOV AL,6BH
ADD AL,A8
By: Jawaher A. Fadhil Computer Science Dept.
AL=AL+A8
6 B
+
A 8
HEX
0
1
2
.
.
9
A
B
C
D
E
F
10
11
12
13
14
15
16
3
1
1 1
AX= 00 13CF= 1

7. Example#2
Write the Assembly language instructions to add the values
6BH and A8H. Place the result in register AX?
MOV AX,0000
MOV AL,6BH
ADD AX,A8
By: Jawaher A. Fadhil Computer Science Dept.
AX=AL+A8
6 B
+
A 8
3
1
1 1
AX= 01 13
CF= 0

8. By: Jawaher A. Fadhil Computer Science Dept.