Unconditional JUMP instruction in 8085 Microprocessor

Microprocessor8085

In 8085 Instruction set,there are a set of jump instructions, which can transfer programcontrol to a certain memory location. So after these branchingmnemonics we shall have to mention 16-bit target address of thelocation. These jump instructions can be divided into two categories– 

  • Unconditional jump instructions and

  • Conditional jump instructions

Here in this section we shall discuss only the unconditional jump instruction. Tre required mnemonic is JUMP a16. Here in this instruction a16 denotes 16-bit memory location address.This instruction does not depend on the current conditions of theflag bits in the flag register. It is a 3-Byte instruction. The firstByte will contain the opcode of the instruction and the second andlast Byte will contain low-order Byte and high-order Byte of theinstruction. Here is the mnemonic details – 

Mnemonics,Operand
Opcode(in HEX)
Bytes
JMP Label
C3
3


The following table shows the JUMP Branching instructions with their meanings.

Opcode
Operand
Meaning
Explanation
JMP
16-bit address
Jump unconditionally
The program sequence is transferred to the memory address given in the operand.


Let us consider the following program segment –

Address
Hex Codes
Mnemonic
Comment
2000
C3
JMP 4000H
Unconditionally Jump to the memory address 4000H
2001
00


Low order Byte of the address
2002
40


High order Byte of the address


The timing diagram against this instruction JMP 4000H execution is as follows –

Summary − So this instruction JMP requires 3-Bytes, 3-Machine Cycles (Opcode Fetch, Memory Read, MemoryRead) and 10 T-States for execution as shown in the timing diagram.

raja
Published on 27-Dec-2018 15:40:28
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