Consider an operating system capable of loading and executing a single sequential user process at a time. The disk head scheduling algorithm used is First Come First Served $$(FCFS).$$ If $$FCFS$$ is replaced by Shortest Seek Time First $$(SSTF),$$ claimed by the vendor to give $$50\% $$ better benchmark results, what is the expected improvement in the $${\rm I}/O$$ performance of user programs?

Using a larger block size in a fixed block size file system leads to

Which of the following requires a device driver?

Listed below are some operating system abstractions (in the left column) and the hardware components. Which matching pairs is correct?

$$\,\,\,\,\,\,\,\,\,\,$$$$\,\,\,\,\,\,\,\,\,\,$$$$\,\,\,\,\,\,\,\,\,\,$$List-$${\rm I}$$
(a) Thread $$\,\,\,\,\,\,\,\,\,\,$$$$\,\,\,\,\,\,\,\,\,\,$$(b) Virtual Address space
(c) File System $$\,\,\,\,\,\,\,\,\,\,$$(d) Signal

$$\,\,\,\,\,\,\,\,\,\,$$$$\,\,\,\,\,\,\,\,\,\,$$$$\,\,\,\,\,\,\,\,\,\,$$List-$${\rm II}$$
(1) Interrupt $$\,\,\,\,\,\,\,$$$$\,\,\,\,\,\,\,\,\,\,$$(2) Memory
(3) $$CPU$$ $$\,\,\,\,\,\,\,\,\,\,\,\,\,$$$$\,\,\,\,\,\,\,\,\,\,$$(4) Disk