Instruction Cycle

It represents the sequence of events that takes place as an instruction is read from memory and executed.

A simple instruction cycle consists of the following

steps

1.    Fetching the instruction from the memory.

2.   Decoding the instruction for operation.

3.   Executing the instruction.

4.   Storing in memory.

In above steps, step 1 and 2 instructions are same and known as fetch cycle and step 3 and 4 instructions are different and known as execute cycle.

 

Instructions Format

Computer understands instructions only in terms of 0’s and 1’s, which is called the machine language. A computer program is a set of instructions that describes the steps to be performed for carrying out a computational task. The processor must have two inputs; instructions and data.

The instructions tell the processor what actions are neeed to be performed on the data. An instruction is further divided into two parts; operation (op-code) and operand.

The op-code represents action that the processor must execute and operand defines the parameters of the action and depends on the operation.

 

Tit-Bits

Machine cycle is defined by the time, that takes to fetch two operands from registers and performs ALU operation and stores the result in a register.

Pipelining improves execution speed by putting the execution steps of several instructions into parallel. It is called implement instruction prefetch.

Sockets are the connecting points of chip on the motherboard.