Draw to show architecture of a process

A process architecture typically includes several key components that reside in memory and are managed by the operating system. Here's a description of its main parts:

1. Text Segment (Code Segment): This read-only segment contains the executable machine code of the program. It's often shareable among multiple processes running the same program.

2. Data Segment: This segment holds global and static variables that are initialized before the program starts. It can be further divided into:

   • Initialized Data Segment: For global and static variables explicitly initialized by the programmer.
   • Uninitialized Data Segment (BSS - Block Started by Symbol): For global and static variables that are not explicitly initialized; they are typically zero-initialized by the system.

3. Heap Segment: This segment is used for dynamic memory allocation during program execution (e.g., using malloc in C or new in C++). It grows upwards from the data segment.

4. Stack Segment: This segment is used for local variables, function parameters, and return addresses during function calls. It grows downwards from a higher memory address.

5. Process Control Block (PCB): While not a memory segment in the same way as the others, the PCB is a data structure maintained by the operating system for each process. It contains vital information about the process, such as:

   • Process ID (PID)
   • Process state (e.g., running, ready, waiting)
   • CPU registers (program counter, stack pointer, general-purpose registers)
   • CPU scheduling information (priority)
   • Memory management information (page tables, base/limit registers)
   • I/O status information (list of open files, I/O devices allocated)
   • Accounting information (CPU time used, time limits)

Visually, the memory layout of a process often looks like this, with the stack and heap growing towards each other:

+-----------------------+  <-- Highest Memory Address
|        Stack          |  (grows downwards)
|                       |
|                       |
|          ...          |
|                       |
|                       |
+-----------------------+
|                       |
|        (Free)         |
|                       |
+-----------------------+
|         Heap          |  (grows upwards)
|                       |
+-----------------------+
|    Uninitialized Data |  (BSS)
+-----------------------+
|    Initialized Data   |
+-----------------------+
|      Text Segment     |  (Code)
+-----------------------+  <-- Lowest Memory Address (0)