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Instructions In Microprocessor

Date: 7 Apr 2013

What is Instruction?

An instruction is a binary pattern designed inside the microprocessor to perform a specific function. In other words, it is actually a command to the microprocessor to perform a given task on specified data.

Instruction Set

The entire group of these instructions are called instruction set. The instruction set determines what functions the microprocessor can perform.

Instruction Format

Instruction Format

Instruction Format

Each instruction has two parts: one is the task to be performed called the operation code (opcode) and the other is the data to be operated on called the operand (data).

Instruction And Word Size

1. One word or one byte Instruction

It includes the opcode and operand in the same byte.

Example: ADD B

2. Two word or two byte Instruction

First byte specifies the opcode and second byte specifies the operand.

Example: MVI A, 05

3. Three word or three byte Instruction

The first byte specifies the opcode and the following two bytes specify the 16 bit address. The second byte is lower order and the other is higher order.

Example: JMP 2085H

  1. 7 Comments to “Instructions In Microprocessor”

    1. […] drive timing and control signals that regulate the data transfer in the system associated with each instruction. It also accepts the control signals generated by other devices in the microprocessor system which […]

    2. […] is a collection of instructions. Instruction specifies an operation such as add, subtract, multiply, store and so on. Computer […]

    3. […] microprocessor in which most instructions operate on n-bit data and its registers are of n-bit size is said to be a n-bit […]

    4. […] any microprocessor instruction, the source and the destination can be a register, memory content or an 8 bit number. In fact, […]

    5. […] is an electronic machine. It has the capacity to act depending on the given instructions. The instruction may be like “add 2 and 3” or “subtract 2 from 3”. But the instructions […]

    6. […] the basic operation regulated by control unit. It consists of sequential fetching and execution of instruction. The fetch state transports an instruction from memory into the microprocessor. The execute state […]

    7. […] code: Sequence of instructions in machine language Machine language: Numeric version of instructions   PC: Program Counter. It is a register acting as pointer to the next instruction   […]