11. When did IBM release the first version of disk operating system DOS version 1.0?

A. 1981
B. 1982
C. 1983
D. 1984
E. None of the above

12. Which of the following is false about disk when compared to main memory?

A. non-volatile
B. longer storage capacity
C. lower price per bit
D. faster
E. None of the above

13. Producer consumer problem can be solved using

A. semaphores
B. event counters
C. monitors
D. all of the above
E. None of the above

14. Most of the microcomputer’s operating systems like Apple DOS, MS DOS and PC DOS, etc. are called disk operating systems because

A. they are memory resident
B. they are initially stored on disk
C. they are available on magnetic tapes
D. they are partly in primary memory and partly on disk
E. None of the above

15. The CPU, after receiving an interrupt from an I/O device

A. halts for a predetermined time
B. hands over control of address bus and data bus to the interrupting device
C. branches off to the interrupt service routine immediately
D. branches off to the interrupt service routine after completion of the current instruction
E. None of the above