Consider the following code fragment:

if (fork() == 0)
{
   a = a + 5;
   printf("%d, %d \n", a, &a);
}
else
{
   a = a - 5;
   printf ("%d, %d \n", a, &a);
}

Let $$u,v$$ be the values printed by the parent process, and $$x,y$$ be the values printed by the child process. Which one of the following is TRUE?

What is the swap space in the disk used for?

Normally user programs are prevented from handling $${\rm I}/O$$ directly by $${\rm I}/O$$ instructions in the for $$CPU$$ having explicit $${\rm I}/O$$ instructions, such $${\rm I}/O$$ protection is ensured by having the $${\rm I}/O$$ instructions privilege in $$CPU$$ with memory mapped $${\rm I}/O$$ there is no explicit $${\rm I}/O$$ instruction. Which one of the following is true for a $$CPU$$ with memory mapped $${\rm I}/O$$?

Consider a disk drive with the following specifications:
$$16$$ surfaces, $$512$$ tracks/surface, $$512$$ sectors/track, $$1$$KB/Sector, rotation speed $$3000$$ rpm. The disk is operated in cycle stealing mode whereby whenever one $$4$$ byte word is ready it it's sent to memory; similarly, for writing, the disk interface reads a $$4$$ byte word from the memory in each $$DMA$$ cycle Memory cycle time is $$40$$nsec. The maximum percentage of time that the $$CPU$$ gets blocked during $$DMA$$ operation is: