Concept Notes: Operating Systems – Process Management
🔹 1. What is a Process?
- A process is a program in execution.
- Every process has:
➤ Program Code (text section)
➤ Process Stack (function calls, local variables)
➤ Data Section (global variables)
➤ Heap (dynamic memory)
🔹 2. Process States
| State | Description |
|---|---|
| New | Process is being created |
| Ready | Process is waiting to be assigned CPU |
| Running | Process is executing |
| Waiting | Process is waiting for I/O |
| Terminated | Process has finished execution |
🔹 3. Process Control Block (PCB)
- Each process is represented by a PCB.
- Contains:
➤ Process ID
➤ Process State
➤ CPU Registers
➤ Memory info
➤ I/O status
🔹 4. Context Switching
- When CPU switches from one process to another, it saves current process state & loads next.
- Overhead but essential for multitasking.
🔹 5. Process Scheduling
| Type | Description |
|---|---|
| Preemptive | Process can be interrupted |
| Non-preemptive | Runs until complete or blocked |
Common Scheduling Algorithms:
- FCFS (First Come First Serve)
- SJF (Shortest Job First)
- RR (Round Robin)
🧠 MCQs – OS Process Management
1️⃣ What is a process in OS?
A) A running thread
B) A program in memory
C) A program in execution
D) A file in hard disk
2️⃣ Which of these is not a process state?
A) Waiting
B) Executing
C) Sleeping
D) Ready
3️⃣ In Round Robin scheduling, each process gets:
A) Equal priority
B) Equal time slice
C) Fixed memory
D) Random CPU time
4️⃣ PCB stands for:
A) Process Computer Block
B) Process Control Block
C) Program Control Block
D) Program CPU Block
5️⃣ Which of the following is a preemptive scheduling algorithm?
A) FCFS
B) SJF (non-preemptive)
C) Round Robin
D) Priority (non-preemptive)
6️⃣ What happens during context switching?
A) The OS shuts down
B) CPU switches from one process to another
C) Memory is formatted
D) File system is changed
7️⃣ A process that has finished execution is in which state?
A) Ready
B) Terminated
C) New
D) Waiting
8️⃣ What does the Ready state mean?
A) Process is being created
B) Process is waiting for input
C) Process is queued for CPU
D) Process is being terminated
9️⃣ Which of the following is not stored in PCB?
A) Program Counter
B) Process ID
C) CPU registers
D) Keyboard layout
🔟 Which process scheduling is most suitable for time-sharing systems?
A) FCFS
B) SJF
C) RR (Round Robin)
D) LIFO
✅ Answer Key
| Q.No | Answer |
|---|---|
| 1 | C |
| 2 | C |
| 3 | B |
| 4 | B |
| 5 | C |
| 6 | B |
| 7 | B |
| 8 | C |
| 9 | D |
| 10 | C |
🧠 Explanations
- Q1: A process is a program that is currently being executed.
- Q2: “Sleeping” isn’t a standard OS process state.
- Q3: Round Robin uses a fixed time quantum for each process.
- Q4: PCB = Process Control Block (holds all process info).
- Q5: Round Robin is preemptive.
- Q6: Context switch = saving current and loading next process info.
- Q7: Finished processes are in the Terminated state.
- Q8: Ready = waiting for CPU assignment.
- Q9: Keyboard layout isn’t process-specific info.
- Q10: Round Robin = best fit for time-sharing environments.
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💬 Comment Task
🗣 What confused you the most – PCB vs Context Switching or Process States?
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