Clocks (also called timers) are essential to the operation of any multiprogrammed system. They maintain the time of day, and prevent one process from monopolizing the CPU. How are clocks implemented?

a)

when a piece of quartz crystal is properly cut and mounted, it can be made to generate a periodic signal of very great accuracy; using electronics this base signal can be multiplied by a small integer to provide synchronizing signal and to cause CPU interrupts

b)the clock is entirely implemented in software including maintaining the time of day, preventing processes from running too long, and accounting for CPU usage

c)the system clock is implemented in very similar way as peoples watches

d)the clock driver simulates multiple physical clocks with a single virtual clock to achieve watch-dog timers

Which of the following statements is incorrect in relation to power management?

a)power management is getting attention because of environmental considerations, and because of battery powered computers

b)	reducing energy consumption can be achieved by reducing the number of transistors on a chip

c)	from hardware perspective, an approach to battery conservation is to provide several states to the CPU, memory, I/O devices, such as: on, sleeping, hibernating, and off

d)	from operating system perspective, it needs to make a decision when and which devices to shut down, in order to conserve energy; the most important ones are the display and the hard disk