Difference Between Program Counter (PC) and Instruction Register (IR)
A computer’s CPU has two important components, the program-counter(PC) & the instruction register(IR). They respectively carry out different operations during the execution cycle of an instruction. Here are the key differences between the two:
Program Counter (PC) |
Instruction Register (IR) |
---|---|
A program counter is a register which stores the address of the next instruction to be retrieved from the memory. It indicates the place in the memory where the next instruction is kept. |
Instruction register is one of the registers used in holding the present instruction that is currently being executed or decoded by the CPU. It consists of the binary code for the instruction that has been fetched from memory. |
Holds the memory address that will fetch the next instruction. |
It stores a binary code of the currently running instruction. |
The PC ensures that it keeps on recording the order in which instructions will be performed and always points at the address where the next instruction should continue. The PC typically proceeds with an update after it has fetched an instruction from a specified address. |
The instruction is fetched from memory and stored in the IR, whose content is subsequently used by the CPU for decoding and executing. In many cases, information contained in this field is interpreted according to op code stored in register for instructions. |
As the program runs through different steps, the PC gets incremented or changed such that it can direct the computer towards the next instruction sequentially. |
During every cycle, new instructions are fetched from memory and the content of the IR is updated. |
Instruction Register
Do you ever wonder how your computer makes sense of your commands and responds accordingly? What is there to say? It is no magic, but a thing called the Instruction Register. “Fancier” is perhaps one way to say “It’s akin to the conductor at an orchestra where every note (instruction) should be perfect.”
Today in this article, we are going to explore about mystery that exists in the Instruction Register. Whether you are techie or just anyone who is interested in knowing what it actually does inside one’s computer; here comes our trip to unraveling these mysteries. Therefore, fasten you seat belts, come with me and allow us take a close look at the Instruction Register but in an easy-to-understand version.
- Central Processing Unit (CPU): These include a central processing unit (CPU) that is responsible for interpreting and following instructions from memory stored within various parts of a computing system. This unit has several parts which include the Instruction Register, ALU, and the Control Unit.
- Memory: Data and instructions are stored in memory in a computer system. Memory communicates with the CPU in the sense that it fetches, stores as well as processes the data.
Table of Content
- What is an Instruction Register?
- What is Program Counter?
- Difference Between Program Counter (PC) and Instruction Register (IR)
- How do Instruction Registers Work?
- Workflow Diagram of Instruction Register
- Types of Instruction Register
- Features of Instruction Register
- Importance of Instruction Register
Contact Us