GATE CSE 1996 | Question: 1.20, ISRO2008-56

Question

Which of the following is an example of spooled device?

• A. A line printer used to print the output of a number of jobs

• B. A terminal used to enter input data to a running program

• C. A secondary storage device in a virtual memory system

• D. A graphic display device

Comments

Why B) is wrong ? I think A), B) both should be answer. Check here

“ The most common can be found in I/O devices like keyboard printers and mouse”.

 

Answer 1

Answer is (A).

Spooling(simultaneous peripheral operations online) is a technique in which an intermediate device such as disk is interposed between process and low speed i/o device. For ex. in printer if a process attempt to print a document but printer is busy printing another document, the process, instead of waiting for printer to become available,write its output to disk. When the printer become available the data on disk is printed. Spooling allows process to request operation from peripheral device without requiring that the device be ready to service the request.

Comments

I think option B is also correct (please correct me if I am wrong). As we know keyboard is a slow input peripheral, so it should also be considered as a spooled device.

As in the link  https://en.wikipedia.org/wiki/Spooling it is mentioned

for slow input peripherals, such as a card reader, a spooler can maintain a sequence of computational jobs waiting for data, starting each job when all of the relevant input is available

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I think option B could not be the answer. In comparison to printer, keyboard is very fast device so it doesn't require spooling at all.

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in comparistion to printer keyboard is slower right because keyboard runs at user speed where as printer at internal motor or component speed??? not sure tho someone clarify

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Why not option D?

Answer 2

A.

http://en.wikipedia.org/wiki/Spooling

Comments

What is the meaning of terminal in option b here?

Answer 3

Spool Device

Spool Device is a buffer that is used to store/hold output for a device . Certain devices such as tape drives and printers are incapable of multiplexing different I/O requests from different applications at the same time . The OS performs the operation by simply using spooling process which is handled by in-kernel thread or system daemon process , since printers can only service one request at a time so by using spooling process the different requests (output from the application ) are spooled to a disk file which are later queued and transferred to the printer one at a time.

 

(A) is the correct answer as Printer cannot accept interleaved data-streams , it needs spooling to service multiple requests .

Answer 4

ANSWER IS: (A)

Spooling is like having a waiting room for tasks that need to use a slow device (like a printer).

• Imagine you want to print something, but the printer is already busy with someone else's document. Instead of making you wait, the system takes your document and puts it in a "waiting area" (like a folder on the computer's disk).
• When the printer finishes its current job, it goes to the waiting area, picks up the next document, and prints it.

Why Spooling is Useful:

• No Waiting: You don’t have to stand around until the printer is free. You can go back to doing other work.
• Efficient: The printer doesn’t need to wait for you to send data. It always has something ready to print from the waiting area.
• Fair Processing: The waiting area works like a queue, so jobs are handled one at a time, in order.

Answer 5

Correct Answer is (A)

In operating systems, a spooled device refers to a device (such as a printer) that utilizes a spooling (Simultaneous Peripheral Operations On-line) technique for handling input/output operations.

When a spooled device is used, data to be printed or processed is first stored in a buffer or a spool file on the system's disk or in memory. This allows the system to handle multiple requests concurrently without having to wait for the device to become available. The spooling system then manages the process of transferring data from the spool file to the device, allowing the application to continue its operation without waiting for the device to finish processing.

Spooling helps improve system performance and efficiency by decoupling the device operation from the application, reducing idle time, and enabling multiple tasks to use the same device simultaneously. It is commonly used for printers, where multiple users may submit print jobs simultaneously, and the spooler manages the print queue and schedules jobs for printing.

Answer 6

BEST ANSWER

SO OPTION A IS CORRECT