Computer Organization and Architecture Multiple Choice Questions on “Bus Arbitration”.
1. To resolve the clash over the access of the system BUS we use ______
a) Multiple BUS
b) BUS arbitrator
c) Priority access
d) None of the mentioned
Answer: b
Clarification: The BUS arbitrator is used to allow a device to access the BUS based on certain parameters.
2. The device which is allowed to initiate data transfers on the BUS at any time is called _____
a) BUS master
b) Processor
c) BUS arbitrator
d) Controller
Answer: a
Clarification: The device which is currently accessing the BUS is called as the BUS master.
3. ______ BUS arbitration approach uses the involvement of the processor.
a) Centralised arbitration
b) Distributed arbitration
c) Random arbitration
d) All of the mentioned
Answer: a
Clarification: In this approach, the processor takes into account the various parameters and assigns the BUS to that device.
4. The circuit used for the request line is a _________
a) Open-collector
b) EX-OR circuit
c) Open-drain
d) Nand circuit
Answer: c
Clarification: None.
5. The Centralised BUS arbitration is similar to ______ interrupt circuit.
a) Priority
b) Parallel
c) Single
d) Daisy chain
Answer: d
Clarification: None.
6. When the processor receives the request from a device, it responds by sending _____
a) Acknowledge signal
b) BUS grant signal
c) Response signal
d) None of the mentioned
Answer: b
Clarification: The Grant signal is passed from one device to the other until the device that has requested is found.
7. In Centralised Arbitration ______ is/are is the BUS master.
a) Processor
b) DMA controller
c) Device
d) Both Processor and DMA controller
Answer: d
Clarification: The BUS master is the one that decides which will get the BUS.
8. Once the BUS is granted to a device ___________
a) It activates the BUS busy line
b) Performs the required operation
c) Raises an interrupt
d) All of the mentioned
Answer: a
Clarification: The BUS busy activated indicates that the BUS is already allocated to a device and is being used.
9. The BUS busy line is made of ________
a) Open-drain circuit
b) Open-collector circuit
c) EX-Or circuit
d) Nor circuit
Answer: b
Clarification: None.
10. After the device completes its operation _____ assumes the control of the BUS.
a) Another device
b) Processor
c) Controller
d) None of the mentioned
Answer: b
Clarification: After the device completes the operation it releases the BUS and the processor takes over it.
11. The BUS busy line is used __________
a) To indicate the processor is busy
b) To indicate that the BUS master is busy
c) To indicate the BUS is already allocated
d) None of the mentioned
Answer: c
Clarification: None.
12. Distributed arbitration makes use of ______
a) BUS master
b) Processor
c) Arbitrator
d) 4-bit ID
Answer: d
Clarification: The device uses a 4bit ID number and based on this the BUS is allocated.
13. In Distributed arbitration, the device requesting the BUS ______
a) Asserts the Start arbitration signal
b) Sends an interrupt signal
c) Sends an acknowledge signal
d) None of the mentioned
Answer: a
Clarification: None.
14. How is a device selected in Distributed arbitration?
a) By NANDing the signals passed on all the 4 lines
b) By ANDing the signals passed on all the 4 lines
c) By ORing the signals passed on all the 4 lines
d) None of the mentioned
Answer: c
Clarification: The OR output of all the 4 lines is obtained and the device with the larger value is assigned the BUS.
15. If two devices A and B contesting for the BUS have ID’s 5 and 6 respectively, which device gets the BUS based on the Distributed arbitration.
a) Device A
b) Device B
c) Insufficient information
d) None of the mentioned
Answer: b
Clarification: The device Id’s of both the devices are passed on the lines and since the value of B is greater after the Or operation it gets the BUS.