In 8085 Instruction set, we are having one mnemonic JC a16, which stands for “Jump if Carry” and “a16” stands for any 16-bit address. This instruction is used to jump to the address a16 as provided in the instruction. But as it is a conditional jump so it will happen if and only if the present carry flag value is 1.If carry flag value is 0, program flow continues sequentially. It is a 3-Byte instruction.Mnemonics, OperandOpcode(in HEX)BytesJC LabelDA3Let us consider one example of this instruction type JC 4000H. It is a 3-Byte instruction. The result of execution of this instruction ... Read More

In 8085 Instruction set, we are having one mnemonic JNC a16, which stands for “Jump if Not Carry” and “a16”stands for any 16-bit address. This instruction is used to jump to the address a16 as provided in the instruction. But as it is a conditional jump so it will happen if and only if the present carry flag value is 0. If carry flag value is 1, program flow continues sequentially. It is a 3-Byte instruction.Mnemonics, OperandOpcode(in HEX)BytesJNCLabelD23Let us consider one example of this instruction type JNC 4000H. It is a 3-Byte instruction. The result of execution of this instruction ... Read More

In 8085 Instruction set, there are a set of jump instructions, which can transfer program control to a certain memory location. So after these branching mnemonics, we shall have to mention 16-bit target address of the location. These jump instructions can be divided into two categories– Unconditional jump instructions andConditional jump instructionsHere we shall discuss conditional jump instructions in details. Under conditional Jump instructions, we are having 8 different mnemonics. We know that there are 5 flag bits in 8085 Flag register. They are S, Z, P, Cy, AC. Out of them only on AC flag bit, there is no jump ... Read More

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 andConditional jump instructionsHere 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 ... Read More

In 8085 Instruction set, there are a set of jump instructions, which can transfer program control to a certain memory location. So after these branching mnemonics we shall have to mention 16-bit target address of the location. These jump instructions can be divided into two categories– Unconditional jump instructions andConditional jump instructionsUnder unconditional jump instructions there is only one mnemonic i.e. JUMP. But under conditional Jump instructions we are having 8 different mnemonics. We know that there are 5 flag bits in 8085 Flag register. They are S, Z, P, Cy, AC. Out of them only on AC flag bit, there ... Read More

In 8085 Instruction set, there a set of instructions which can Accumulator contents left orright. It is to be noted here that rotate operation can be performedonly on Accumulator contents. These instructions set is listed below– Mnemonics, OperandOpcode(in HEX)BytesRAL171RAR1F1RLC071RRC0F1Mnemonic RLC stands for “Rotate Left Accumulator”. It rotates the Accumulator contents to the left by 1-bit position. The following Fig. shows the operation explicitly – In this fig. it has been depicted that the mostsignificant bit of the Accumulator will come out and left rotate willcreate an empty space at the least significant bit place and thiscome out bit will be copied at ... Read More

In 8085 Instruction set, we are having a set of instructions to perform compare operation where we shall compare two operands, and which will affect the status flags values depending on the result of the comparison. In this operation, 8085 imposes the restriction that one of the operands must be in the Accumulator. The other operand can be one of the following –ClassificationsExamplesThe other operand can be kept in 8-bit immediate data in the instruction.CPI 43HCPI FFHThe other 8-bit operand can be kept in a memory location and whose memory address will be pointed by HL register pair.CMP MThe other ... Read More

In 8085 Instruction set, there are two instructions to control the Cy flag bit content. Thesemnemonics are STC and CMC. Both are 1-Byteinstructions. There hex codes are given in the following table – Mnemonics, OperandOpcode(in HEX)BytesSTC371CMC3F1Using STC instruction we can set the Cy flag bit to 1 irrespective of itsprevious value. And using CMC instruction we can complement the current value of the Cy fag bit andresult will update the current Cy flag bit value. Here STC stands for “SeT the Carry flag” and CMC stands for “CoMplement the Carry flag”. Note that, there isno dedicated instruction in 8085 instruction set ... Read More

In 8085 Instruction set, logical type there is one complement instruction with the mnemonic CMA. It actually stands for “CoMplement the Accumulator”. It performs1's complement operation on the current contents of Accumulator, and the result is stored back in the Accumulator replacing its previous contents. It is to be noted that, there are no other instructions tocomplement any other register’s contents. Though it is a logicaltype of instruction, Flag bits are not affected by the execution of this instruction. It occupies only 1 Byte in memory. Mnemonics, OperandOpcode(in HEX)BytesCMA2F1Let us suppose that example, the initial content of Accumulator is AAH i.e. ... Read More

In 8085 Instruction set, and specially in its logical group of instructions, we have AND, OR, XOR, NOT type of instructions. 8085 does not have instructions to perform NAND, NOR, XNOR operations directly. Now let us discuss the instructions to perform XOR operations only.To perform XORing of two numbers, 8085 imposes the restriction that one of the operands must be kept in the Accumulator. The other operand can be at any one of the following possible locations −ClassificationsExamplesThe other operand can be kept in 8-bit immediate data in the instruction.XRI 43HXRI FFHThe other 8-bit operand can be kept in a ... Read More