GATE CSE 1996 | Question: 1.18

Question

The process state transition diagram in the below figure is representative of

• A. a batch operating system

• B. an operating system with a preemptive scheduler

• C. an operating system with a non-preemptive scheduler

• D. a uni-programmed operating system

Comments

@Arjun @ajaysoni1924 Sir, how can a process go from terminated state to running state ?

---

@Satbir  the arrow is wrong printed , refer https://www.geeksforgeeks.org/gate-gate-cs-1996-question-18/

---

Please, update the diagram in the Go book. The arrow (terminated → running) is wrong printed.

---

it's updated now

---

Maybe not directly related to the question, but after a process is blocked, it is stuck there and cannot even terminate?

---

Okay, the arrow is wrong - the arrow should be from Blocked to Ready and not vice-versa.
Refer https://www.geeksforgeeks.org/questions/the-process-state-transition-diagram-in-below-figure-is/

---

why isnt there any transition from the Blocked state?

Answer 1

Answer is (B). The transition from running to ready indicates that the process in the running state can be preempted and brought back to ready state.

Comments

what is uni programmed os in option (D)?

---

The option a. Is batch operating system its not premptive in nature is that the reason for discarding this option? Or there is any other approach?  And  is uniprogrammed os always non preemptive?

---

Uniprogrammed OS allows to run only one program at a time. That's what we can understand but there's no clarity about whether it's preemptive or non-preemptive.

Answer 2

The definitive clue lies in the two bidirectional arrows between the RUNNING and READY states:

1. RUNNING -> READY: This arrow represents preemption (e.g., a timer interrupt or a higher priority process arriving). A process is forced off the CPU even though it hasn't finished its work or blocked for I/O.
2. READY -> RUNNING: This arrow represents scheduling (when the short-term scheduler picks a process to run).

Hence, Option B is Correct

---

Other Options: 

• C. non-preemptive scheduler: In a non-preemptive system, once a process is RUNNING, it cannot be kicked out. It stays on the CPU until it finishes (TERMINATED) or waits for an event (BLOCKED). Therefore, a non-preemptive diagram would completely lack the arrow pointing from RUNNING -> READY.
• A & D. batch / uni-programmed system: These primitive systems run only one process at a time until completion without interactive switching or time-slicing.

---

Batch System (Option A)

• No Multitasking: One job runs directly from start to finish.
• No Queue: Memory holds the OS and exactly one single job. Other jobs wait outside on disk/cards. There is no READY queue in memory.

┌───────┐      ┌─────────┐      ┌────────────┐
│  NEW  │ ───► │ RUNNING │ ───► │ TERMINATED │
└───────┘      └─────────┘      └────────────┘
                    │
                    │ Wants I/O (CPU sits completely idle)
                    ▼
               ┌─────────┐
               │ BLOCKED │
               └─────────┘

---

Uni-Programmed System (Option D)

• Has a Queue: : Memory holds the OS and multiple waiting jobs inside a structured READY queue. However, the CPU can still only pick and execute one program at a time non-preemptively.
• No Preemption: A running process cannot be kicked back to READY.

┌───────┐      ┌───────┐      ┌─────────┐      ┌────────────┐
│  NEW  │ ───► │ READY │ ───► │ RUNNING │ ───► │ TERMINATED │
└───────┘      └───────┘      └─────────┘      └────────────┘
                   ▲               │
                   │               │ Wants I/O
                   │ I/O Done      ▼
                   └───────────┌─────────┐
                               │ BLOCKED │
                               └─────────┘

---

---

Answer 3

Best Answer

Since there is arrow from Running to Ready So it is Pre-emptive

Answer 4

Option B is TRUE

Option A: False Batch system is not the correct answer .Proof is taken from 

Galvin OS ninth edition page number :66

Batch os many processes are submitted and then can be executed immediately 

BATCH SYSTEM processed jobs in bulk,with predetermined input from files or other data sources.

From these we can conclude that Batch os executes jobs sequentially and no preemption.

So 

Comments

@buriburizaemon
Bro if its gets blocked, then from Running->Blocked State->Ready state, not directly to ready state right??

 

---

" A process that is ready to run but waiting for the CPU can be considered blocked " - Galvin

now from the above statement ,if the job needs resources (like I/O), it will go to the Blocked state first and then return to Ready once resources are available, i think 

@Adib9687 for your question

Preemptive : 

i think it may go to ready state directly because of the preemptive scheduler. It can also go to Blocked if waiting for resources before returning to Ready.

for Non Preemptive : 

it will not go to ready state as the jobs are using non preemptive scheduler, once the process is in running state.They will only transition to the Blocked state if they require resources (like I/O). Otherwise, they continue to execute until completion.

for Batch system :

the job are secheduled sequentially, can queue and manage resources, The scheduler may allow for resource waiting that could lead to a Blocked state but it will not preempt jobs while they are in the running state

correct my understanding if i am wrong here !! 

---

https://gateoverflow.in/2237/gate-cse-1997-question-3-6
Batch Operating system -> Batch processing -> FIFO ( so non-preemtive) @buriburizaemon