I/O System MCQs

1. A printer is a:

a) Shared device b) Dedicated device c) Virtual device d) None

Correct Answer: b) Dedicated device

Explanation:
Printers are typically dedicated devices that can only be used by one process at a time, though they may be shared through spooling.

2. Virtual devices use:

a) Spooling b) Buffering c) Both d) Neither

Correct Answer: a) Spooling

Explanation:
Virtual devices are created through spooling (Simultaneous Peripheral Operations Online) which queues requests to make slow devices appear faster.

3. Magnetic tapes are:

a) Direct access b) Serial access c) Random access d) None

Correct Answer: b) Serial access

Explanation:
Magnetic tapes are sequential-access devices that require linear traversal to reach specific data, unlike disks which allow direct access.

4. Hard disks are:

a) Sequential access b) Direct access c) Both d) Neither

Correct Answer: b) Direct access

Explanation:
Hard disks are direct-access storage devices (DASD) that can access any block directly by moving the read/write head to the correct track and sector.

5. FCFS services requests:

a) In order b) By seek time c) By priority d) None

Correct Answer: a) In order

Explanation:
First-Come-First-Served (FCFS) processes I/O requests in the order they arrive, without optimizing for seek time or location.

6. SSTF may cause:

a) Starvation b) High throughput c) Both d) Neither

Correct Answer: c) Both

Explanation:
Shortest-Seek-Time-First (SSTF) improves throughput by minimizing head movement but may starve requests that are far from the current head position.

7. SCAN is also called:

a) Elevator algorithm b) Round-robin c) Priority scheduling d) None

Correct Answer: a) Elevator algorithm

Explanation:
The SCAN algorithm moves the disk arm back and forth across the disk (like an elevator) servicing requests along its path.

8. C-SCAN moves:

a) Only inward b) Only outward c) Both directions d) None

Correct Answer: b) Only outward

Explanation:
Circular SCAN (C-SCAN) services requests only while moving outward (or inward), then returns to the start without servicing requests on the return trip.

9. A channel manages:

a) CPU execution b) I/O operations c) Memory d) None

Correct Answer: b) I/O operations

Explanation:
I/O channels are specialized processors that handle data transfers between devices and memory, offloading this work from the main CPU.

10. Control units handle:

a) Data transfer b) Process scheduling c) Both d) Neither

Correct Answer: a) Data transfer

Explanation:
Control units manage the operation of specific device types (like disk controllers) and handle the actual data transfer between devices and channels.

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