CHAPTER 4
SECTION 4.8
Instruction set 8085
1. DATA TRANSFER GROUP INSTRUCTION.
4. ARITHMETIC GROUP INSTRUCTION.
7. LOGICAL GROUP INSTRUCTION.
10. BRANCHING GROUP INSTRUCTION.
Classification of instruction set:
1. 1 BYTE INSTRUCTION:
i. MOV C,A
ii. ADD B
3. 2 BYTE INSTRUCTION:
i. MVI A, 8-bit data
ii. OUT 8-bit address
5. 3 BYTE INSTRUCTION
i. LDA 2050
ii. STAX H
Length of Instructions:
SOURCE TO DESTINATION
LENGTH OF INSTRUCTION
EXAMPLES:
1. LDAX Rp
2. STAX Rp
3. LXI Rp, 16 bit immediate data
Data transfer group:
LENGTH OF INSTRUCTION
FUNCTION
FLAGS AFFECTED
T-STATE
LDAX Rp
LDAX B
Before execution
A00
B20
C01
D E
H L
2000
200150
2002
LDAX B
After execution
A50
B20
C01
D E
H L
2000
200150
2002
LENGTH OF INSTRUCTION
FUNCTION
FLAGS AFFECTED
T-STATE
STAX Rp
STAX D
Before execution
A20
B C
D25
E05
H L
2504
250510
2506
STAX D
After execution
A20
B C
D25
E05
H L
2504
250520
2506
LENGTH OF INSTRUCTION
FUNCTION
FLAGS AFFECTED
T-STATE
LXI Rp, 16 bit immediate data
LXI B, 1507H
Before execution
A
B00
C00
D E
H L
2504
2505
2506
LXI B, 1507H
After execution
A
B15
C07
D E
H L
2504
2505
2506
PERFORMS ARITHMETIC OPERATIONS.
LENGTH OF INSTRUCTION.
EXAMPLES:
1. ADD Rs
2. INR R
3. DCR R
Arithmetic group
LENGTH OF INSTRUCTION
FUNCTION
FLAGS AFFECTED
T-STATE
ADD Rs
ADD B
Before execution
A93
BB
C7
D E
H L
2504
2505
2506
ADD B
After execution
A4A
BB
C7
D E
H L
2504
2505
2506
Procedure
LENGTH OF INSTRUCTION
FUNCTION
FLAGS AFFECTED
T-STATE
INR R
INR R
Before execution
A93
B C
DB
E7
H L
2504
2505
2506
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