GATE CSE 1996 | Question: 1.24

Question

For the daisy chain scheme of connecting I/O devices, which of the following statements is true?

• A. It gives non-uniform priority to various devices
• B. It gives uniform priority to all devices
• C. It is only useful for connecting slow devices to a processor device
• D. It requires a separate interrupt pin on the processor for each device

Comments

Along with option A, What about option C ?

As it is interrupt driven I/O , it is only useful for connecting slow devices to a processor device

this statement also makes sense.

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Asked in GATE 2020

Answer 1

Daisy chaining approach tells the processor in which order the interrupt should be handled by providing priority to the devices.
In daisy-chaining method, all the devices are connected in serial. The device with the highest priority is placed in the first position, followed by lower priority devices. The interrupt pin is common to all.

So answer is option (A).

Comments

VAD – Vector Address

PI(P1) – Priority In

PO(P0) – Priority Out

Source: https://www.geeksforgeeks.org/priority-interrupts-sw-polling-daisy-chaining/

Answer 2

nly useful for slow devices is not correct because

e.g. Firewire interface which is fast cable use to connect devices in daisy chain scheme

.