8085 BRANCHING INSTRUCTIONS

REVIEW ON INSTRUCTION SET BASED ON FUNCTIONS

 

DATA TRANSFER	ARITHMETIC	LOGICAL
MOV	ADD	CMP , CPI
MVI	ADI	CMA
LXI	ADC	CMC
LDA	ACI	STC
STA	DAD, DAA	RAR
LDAX	SUB	RAL
STAX	SUI	RRC
LHLD	SBB	RLC
SHLD	SBI	ANA , ANI
XCHG	INR, DCR	ORA ,ORI
	INX, DCX	XRA , XRI

Task	Opcode	Operand	Byte(s)	Flags	Addressing Mode
Jump to 16-bit address	JMP	16-bit address	03	None	Direct

Task	Opcode	Operand	Byte(s)	Flags	Addressing Mode
Jump on Carry i.e CY=1	JC	16-bit address	03	None	Direct
Jump on No Carry i.e CY=0	JNC	16-bit address	03	None	Direct
Jump on Even Parity i.e P=1	JPE	16-bit address	03	None	Direct
Jump on Odd Parity i.e P=0	JPO	16-bit address	03	None	Direct
Jump on Zero i.e Z=1	JZ	16-bit address	03	None	Direct
Jump on No Zero i.e Z=0	JNZ	16-bit address	03	None	Direct
Jump on Minus i.e S=1	JM	16-bit address	03	None	Direct
Jump on Positive i.e S=0	JP	16-bit address	03	None	Direct

Task	Opcode	Operand	Byte(s)	Flags	Addressing Mode
Call a subroutine	CALL	16-bit address	03	None	Direct

Task	Opcode	Operand	Byte(s)	Flags	Addressing Mode
Call on Carry i.e CY=1	CC	16-bit address	03	None	Direct
Call on No Carry i.e CY=0	CNC	16-bit address	03	None	Direct
Call on Even Parity i.e P=1	CPE	16-bit address	03	None	Direct
Call on Odd Parity i.e P=0	CPO	16-bit address	03	None	Direct
Call on Zero i.e Z=1	CZ	16-bit address	03	None	Direct
Call on No Zero i.e Z=0	CNZ	16-bit address	03	None	Direct
Call on Minus i.e S=1	CM	16-bit address	03	None	Direct
Call on Positive i.e S=0	CP	16-bit address	03	None	Direct

 The branching instructions are the most powerful instruction because

they allow the microprocessor to change the sequence of the program ,

either unconditionally or under certain test conditions.The

microprocessor is a sequential machine, it executes the machine code

from one memory location to the next Branch instructions instruct the

microprocessor to go to a different memory location, and the microprocessor 

continues executing machine code from that next location.

The branch instructions are classified in three categories

Jump Instructions

1. Unconditional Jump
2. Conditional Jump

Call Instructions

1. Unconditional 
2. Conditional 

Return Instructions 

1. Unconditional 
2. Conditional 

Jump Instructions

Unconditional Jump
JMP:  Jump Unconditionally To Specified Memory Location
 
Description: It is a 3-byte instruction which transfers the program
sequence to the memory location specified by the 1
6-bit address in the operand without checking any condition. 
Example:

To instruct the microprocessor to go to the memory
location F009H

Conditional Jump 
Instruction:  JMP F009H
Call Instructions

Unconditional Call
CALL:  Unconditionally Call To The Subroutine 

Description: The program sequence is transferred to the address
specified by the operand. Before the transfer, address
of the next instruction to CALL( the contents of the
program counter) is pushed on the stack

Instruction:  CALL 2050H
Call Instructions

Example: 

To instruct the microprocessor to call a subroutine located at 2050H

Conditional Call
 

Task	Opcode	Operand	Byte(s)	Flags	Addressing Mode
Return from subroutine	RET		01	None	Implied/ Implicit

Call Instructions
Unconditional Ret
RET :  Return From Subroutine Unconditionally
Description: The program sequence is transferred from the subroutine to the calling program. The two bytes from the top of the stack are copied into the program counter and the program execution begins at the new address.

Note: This instruction is used in conjunction with the CALL or conditional call instructions.

Call Instructions
Conditional Ret  

 

Task	Opcode	Operand	Byte(s)	Flags	Addressing Mode
Return on Carry i.e CY=1	RC		01	None	Implied/ Implicit
Return with No Carry i.e CY=0	RNC		01	None	Implied/ Implicit
Return on Parity i.e P=1	RPE		01	None	Implied/ Implicit
Return on Parity i.e P=0	RPO		01	None	Implied/ Implicit
Return on Zero i.e Z=1	RZ		01	None	Implied/ Implicit
Return on No Zero i.e Z=0	RNZ		01	None	Implied/ Implicit
Return on Minus i.e S=1	RM		01	None	Implied/ Implicit
Return on Positive i.e S=0	RP		01	None	Implied/ Implicit