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Mnemonic means memory aid.
Instruction mnemonics are easy to remember short alphanumeric strings that stand for op codes.
Op codes are numbers that are understood by the computer and command it to perform various operations. They are usually inherently difficult for humans to remember.
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What are the difference between opcode and operand?
An opcode is an instruction. An operand is information used by the opcode. Not all opcodes require operands.
What is the difference between operand and opcode?
op code is used as the value of instruction . And operand is address location where the instruction can meet.
How an assembler converts assembly mnemonics to machine language?
Each mnemonic maps directly to a machine instruction code, known as an opcode. Some mnemonics map to more than one opcode, however the instruction's operand types will determine which specific opcode will be generated.
Difference between LDA and STA instruction in 8085?
In the 8085, the LDA instruction loads the accumulator from memory, while the STA instruction stores the accumulator to memory. LDA is a read, while STA is a write. LDA is opcode 3AH, while STA is opcode 32H.
What is opcode fetch?
The process of transferring instruction codes from memory location to instruction queue register is called opcode fetch.
Is instruction opcode a type of memory?
The instruction opcode is a type of data contained in memory, pointed to by the PC (Program Counter) register.
What is the necessity to use opcode fetch cycle for every instruction?
The microprocessor uses an opcode fetch cycle for every instruction because it has to know the opcode in order to execute it, and that is located in memory.
What is the difference between LDA and STA instructions?
In the 8085, the LDA instruction loads the accumulator from memory, while the STA instructionstores the accumulator to memory. LDA is a read, while STA is a write. LDA is opcode 3AH, while STA is opcode 32H.
What happens to ip after completion of fetch of instruction code?
IP is incremented after fetch of instruction opcode. Specifically, IP is incremented by the number of opcode bytes.
How does microprocessor differentiate between data and instruction code?
i) Instruction code deals only with mnemonics and its corresponding opcode but data code refers to your data like 10h which is always of 8 bits or a particular address say 8080h which is of 16 bits. ii) Data is your input to the instruction but an opcode is native to your machine. iii) Data is user specific instruction while opcode is machine specific instruction iv) You can alter data code but you cannot modify an instruction opcode.
Difference between code segment and data segment of an instruction?
In the 8086/8088 microprocessor, the code segment is used to fetch the opcode and any additional instruction bytes that might be part of the instruction, while the data segment is used to fetch and/or store any operand bytes that the instruction requires to be manipulated.This is in the case of no segment override prefix.
How does 8086 differentiate between op code and instruction data?
The 8086 microprocessor differentiates between opcodes and instruction data through its instruction format, where the first byte(s) typically represent the opcode, while subsequent bytes represent operands or data. The opcode specifies the operation to be performed, while the data can include registers, memory addresses, or constants. Additionally, the instruction pointer and segment registers help the processor understand the context of the instruction, allowing it to interpret the opcode and associated data correctly. This structured format enables the 8086 to efficiently decode and execute instructions.
