1. FI (fetch instruction) - get the next instruction 2. DI (decode instruction) - decode the opcode and operands 3. CO (calculate operands) - calculate EA of the operands 4. FO (fetch operands) - fetch operands from memory (not necessary for register data) 5. EI (execute instruction) - execute instruction storing result if necessary 6. WO (write operand) - write the result in MEM
3 for opcode fetch, 1 for opcode decode, 3 for operand fetch, and 3 for opcode store, for a total of 10, not including wait states.
Instruction execution can be divided into five phases. These are Phase-I: INSTRUCTION FETCH (IF) II: INSTRUCTION DECODE & OPERAND FETCH (ID) III: EXECUTION (EX) V: MEMORY OPERATION (MEM) V: WRITE BACK (WB) - Regards, Subhradip Das
The possible states that define an instruction execution are as follows: Instruction address calculation - Determine the address of the next instruction to be executed. Instruction fetch - Read instruction from its memory location into the processor. Instruction operation decoding - Analyze instruction to determine type of operation to be performed and operand to be used. Operand address calculation - If the operation involves reference to an operand in memory or available via I/O, then determine the address of the operand. Operand fetch - Fetch the operand from memory or read it in from I/O. Data operation - Perform the operation indicated in the instruction. Operand store - Write the result into memory or out to I/O.
Fetch Decode Execute. This is the cycle that processors will follow. Fetch the Instruction, Decode it into machine code, Execute the commands
The two-phase process for executing instructions on a typical CPU involves a fetch step and an execute step. Fetch is where the instruction is loaded from memory and execute is where the actions detailed in the instruction are carried out.
1. Fetch 2. Decode 3. Execute
1.fetch 2.decode 3.execute
there are 4 phases in instruction cyclefetchdecodeexecutestore
when we execute a program, the starting address is loaded in the program counter. Then for each instruction the processor goes through fetch-decode-execute states. At the fetch state the instruction code is fetched then decoded to understand what exactly has to be done. Then finally it executes that instruction. This process goes on till it reaches the end of the program.
Three for opcode fetch, one for decode, two to process the manipulation of the stack pointer.
The CALL instruction uses 18 clock cycles. 3x3 fetch, 2x3 store, 1x1 decode, 2x1 decrement.