In 8085 Instruction set, STC stands for “SeT the Carry flag”. It sets the cy flag to the 1 state, immaterial of its earlier value. It performs set operation on the cy flag, and the result is stored back in the cy flag. Mnemonics, Operand Opcode(in HEX) Bytes STC 37 1 The result of execution of this instruction has been depicted in the following tracing table − Before After (Cy) 1 1 (Cy) 0 1 Address Hex Codes Mnemonic Comment ... Read More

In 8085 Instruction set, CMC stands for “CoMplement the Carry flag”. It performs complement operation on the cy flag, and the result is stored back in the cy flag. Mnemonics, Operand Opcode(in HEX) Bytes CMC 3F 1 The result of execution of this instruction has been depicted in the following tracing table − Before After (Cy) 1 0 Address Hex Codes Mnemonic Comment 2001 3F CMC Complement of Cy when Cy=1 The timing diagram against this instruction CMC execution is as follows − Summary − So this instruction CMC requires 1-Byte, 1-Machine Cycle (Opcode Fetch) and 4 T-States for execution as shown in the timing diagram.

In 8085 Instruction set, XRI is a mnemonic that stands for “eXclusive OR Immediate with Accumulator” and “d8” stands for any 8-bit data. This instruction is used to Ex-OR 8-bit immediate data with the Accumulator. The result of Ex-ORing will be stored in the Accumulator overwriting its previous content. As it is a Logical instruction, so S, P, and Z flags are affected based on the result thus produced. Cy and AC are reset to 0. It occupies 2-Bytes in memory during execution. Mnemonics, Operand Opcode(in HEX) Bytes XRI Data EE 2 Let ... Read More

In 8085 Instruction, XRA is a mnemonic that stands for “eXclusive OR Accumulator” and “R” stands for any of the following registers, or memory location M pointed by HL pair. R = A, B, C, D, E, H, L, or M This instruction is used to Ex-OR contents of R with the Accumulator. The result of Ex-OR operation will be stored in the Accumulator. As R can have any of the eight values, there are eight opcodes for this type of instruction. It occupies only 1-Byte in memory. Mnemonics, Operand Opcode(in HEX) Bytes ... Read More

In 8085 Instruction set, ORI is a mnemonic that stands for “OR Immediate with Accumulator” and “d8” stands for any 8-bit data. This instruction is used to OR 8-bit immediate data with the Accumulator. The result of ORing will be stored in the Accumulator itself. As it is a logical instruction, the S, P, and Z flags are affected based on the result. Cy and AC are reset to 0. It occupies 2-Bytes in memory. Mnemonics, Operand Opcode(in HEX) Bytes ORI Data F6 2 Let us consider ORI CDH as an example instruction ... Read More

In 8085 Instruction set, ORA is a mnemonic, which stands for “OR Accumulator” and “R” stands for any of the following registers, or memory location M pointed by HL pair. R = A, B, C, D, E, H, L, or M This instruction is used to OR contents of R with the Accumulator. The result of OR operation will be stored back in the Accumulator. As R can have any of the eight values, there are eight opcodes for this type of instruction. It occupies only 1-Byte in memory. Mnemonics, Operand Opcode(in HEX) Bytes ... Read More

In 8085 Instruction set, ANI is a mnemonic, which stands for “ANd Immediate with Accumulator” and “d8” stands for any 8-bit or 1-Bytedata. This instruction is used to AND 8-bit immediate data with the Accumulator’s content. The result of this ANDingoperation will be stored in the Accumulator itself over writing its previous content. As it is an arithmetic operation do S, P, and Z flags are affected based on the result. Cy is reset to 0, and AC is set to 1. It occupies 2-Bytes in the memory. Mnemonics, Operand Opcode(in HEX) Bytes ANI Data E6 ... Read More

In 8085 Instruction set, ANA is a mnemonic, which stands for “ANd Accumulator” and “R” stands for any one of the following registers, or memory location M pointed by HL pair. R = A, B, C, D, E, H, L, or M This instruction is used to AND contents of R with Accumulator’s content. The result thus produced for this AND operation will be stored back in to the Accumulator over writing its previous content. As R can have any of the eight values, there are eight opcodes for this type of instruction. It occupies only 1-Byte in ... Read More

In spite of the fact that 8085 is an 8-bit microprocessor, but there are some instructions are there available in the 8085 instruction set which can do 16-bit additions also. As the 8085 internal architecture is only 8-bits, this instruction easily takes double the time needed to add two 8-bit numbers. Here, DAD is a mnemonic, which stands for Double ADd and also rp stands for any one of the following register pairs as mentioned below. rp = BC, DE, or HL As rp can have any of the three values, there are three opcodes for this type ... Read More

In 8085 Instruction set, DCX is a mnemonic that stands for “DeCrementeXtended register” and rp stands for register pair. And it can be any one of the following register pairs − rp = BC, DE, or HL This instruction will be used to subtract 1 from the present content of the rp. And thus the result of the decremented content will remain stored in rp itself. Though, it is an arithmetic instruction, note that flags are not at all affected by the execution of this instruction. A register pair is generally used to store 16-bit memory address. If ... Read More