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