How CPU registers comes into picture during process execution?

ujjwal bansal
3 min readAug 27, 2023


During the program execution, at what stage CPU registers came into picture while performing computation on our program?

As we all know our code is compile from plain English/human-readable language to machine code. This machine code consists primarily of CPU instructions, not data. CPU instructions are the low-level commands that the CPU can directly execute to perform operations like arithmetic, logic, and control flow.

Data, on the other hand, is typically separate from the machine code. Data includes variables, constants, arrays, and other values that the program uses during its execution. This data is not directly included in the machine code itself but is managed separately in memory.

Here’s a breakdown of the components involved:

  1. Machine Code (CPU Instructions):
  • These are the low-level instructions that the CPU can understand and execute.
  • Instructions include operations like arithmetic, logic, data movement, and control flow (branches and jumps).
  • They control the behavior of the program and define how data is manipulated.

2. Data:

  • Data includes variables, constants, arrays, and any other values the program needs to store or manipulate.
  • Data is stored in memory (RAM) and is accessed by the CPU instructions.
  • The machine code instructions reference memory locations where data is stored.

When you compile a program, the compiler generates machine code instructions based on the source code’s logic and structure. The generated machine code includes the sequence of instructions required to perform the operations specified by the program. Data used by the program is stored separately in memory, and the machine code instructions interact with this data during execution.

In summary, machine code primarily consists of CPU instructions that define the program’s logic and operations. Data used by the program is stored in memory and is referenced by the machine code instructions during execution.

Step-1: The discussion we had so far made us clear that before the program can be executed, the machine code, along with any data that the program uses (variables, arrays, etc.), is loaded into RAM. This process is managed by the operating system. Loading the program into RAM allows for faster access and execution compared to running directly from secondary storage (e.g., hard drive).

Step-2(Execution): Once the program’s code and data are in RAM, the CPU fetches instructions from RAM, decodes them, and executes them. The program interacts with the data stored in RAM to perform calculations, process inputs, and produce outputs.

Step-3 Cache Usage: The CPU also uses its cache memory to store frequently accessed instructions and data. Cache memory provides faster access than RAM, helping to reduce the time the CPU spends waiting for data.

Step-4 Registers: During execution, the CPU uses its internal registers to hold data and intermediate results. Registers offer the fastest possible access times.

In essence, loading the program and its data into RAM is an essential step because RAM provides a much faster access time compared to secondary storage like hard drives. This allows the CPU to execute the program more efficiently. Caching and using registers also help optimize execution speed by minimizing data access latencies.





ujjwal bansal

Propagating a life-changing perspective to everyone is my motive. Writing my own expirences or learnings to empower others.