What is instruction cycle

The control unit checks the IR to verify if the instruction has any operands present, specifying indirect addressing. If the indirect addressing is present in the instruction then the indirect cycle has to be run.

These N bits contain the address reference of the operand that has to be fetched. The control unit performs the memory read operation and fetch the address of the operand and transfer it into MBR. Here the indirect cycle gets over.

The execution cycle may be of various form and it totally depends on the type of instruction present in the IR. The execute cycle involves transferring data from registers to registers, read memory or write memory operations, ALU operations. The interrupt cycle starts when there arises an interrupt signal. The PC has the address of the next instruction of the program that has to be executed next.

The content of PC i. So, these are the various forms of the instruction cycle. We have seen the amendment in its structure when there is indirect addressing present in the instructor and even when an interrupt occurs. Your email address will not be published. In a basic computer, each instruction cycle consists of the following phases: Fetch instruction from memory.

Decode the instruction. Read the effective address from memory. Execute the instruction. Input-Output Configuration In computer architecture, input-output devices act as an interface between the machine and the user. The following block diagram shows the input-output configuration for a basic computer. The input-output terminals send and receive information.

The amount of information transferred will always have eight bits of an alphanumeric code. The information generated through the keyboard is shifted into an input register 'INPR'. The information for the printer is stored in the output register 'OUTR'. The transmitter interface receives information from the keyboard and transmits it to INPR. The receiver interface receives information from OUTR and sends it to the printer serially.

Design of a Basic Computer A basic computer consists of the following hardware components. The figure provides a large aspect of the instruction cycle of a basic computer, which is in the design of a state diagram. For an instruction cycle, various states can be null, while others can be visited more than once. What is Instruction Cycle in Computer Architecture? Computer Architecture Computer Science Network.

Previous Page Print Page. The other name of the instruction cycle is the fetch-decode-execute cycle. There are basically four phases in the instruction cycle: fetching an instruction from memory, decoding of the fetched instruction, reading of the address from memory, and the last phase include the instruction execution.

The computer processor executes it. It is defined as the basic cycle carried out in a computer system in which the computer system fetched the instruction from memory, decodes the instruction and then executes the instruction.

It is also known as Fetch-Execute-Cycle. In the computer system, all the instructions are executed in the RAM of the computer system. The CPU is responsible for executing the instruction.

The CPU system first fetches the data and instruction from the main memory and store in the temporary memory, which is known as registers.

This phase is known as the fetch cycle. After fetching an instruction from memory, the next step taken by the CPU is decoding of fetched instruction. This phase is known as the decode phase. The CPU contains an instructions set which contain all the predefined list of instructions.

In the last phase of the instruction cycle, data processing takes place. The instruction executes in this phase, and the result is stored in another register.