Paging is solution to external fragmentation problem which 
is to permit the logical address space of a process to be 
noncontiguous, thus allowing a process to be allocating 
physical memory wherever the latter is available.

micro-kernel based operating systems like minix 
      device drivers  are isolated from kernel and loaded in
their user addressspaces...they will intract with message
passing. speed is very less here because of switching
between kernel and user space and context switching..

macro-kernel based operating systems like windows and linux
   device drivers are part of kernel ..to interact with
kernel need not switch to kernel mode...
speed is high..

When two or more threads of your program are blocked from 
gaining access to a resource and as a result cannot make 
ant progress, such a situation is called Starvation.

The ultimate form of Starvation is Deadlock. Deadlock 
occurs when two or more threads are waiting on a condition 
that cannot be satisfied. Most often a Deadlock occurs when 
two or more threads are each waiting for the other to do 
something.

Semaphores are used to avoid Deadlock situations.

Dead lock is the situation which occurs when a process is
waiting for a resource which is already handled by someother
process and that particular process is waiting for some
other resource to complete its task which is handled by some
other differnt process
it is cyclic

The process is in blocked state, when a process is waiting 
for some event(I/O completion)to occour.

the process is in BLOCKED STATE which waits for an event to 
be occured in order to be executed.

A hard real time system guarantees that critical tasks 
complete on time this goal reqires that all delays in the 
system be bounded from the retrieval of the stored data to 
the time that it takes the o.s to finish any request made 
of it.
A soft real time system where a critical real time task 
gets priority over other tasks and retains that priority
until it completes.As in hard real time system kernel 
delays need to be bounded.

In Vechile we are using Hard RTOS.
Soft RTOS using in Live telecasting, Flight updation...

If HRTOS meets any delay, system ill b destoryed.
Delay is d problem , but delay is possible in SRTOS.

A system is said to be real-time if the total correctness of
an operation depends not only upon its logical correctness,
but also upon the time in which it is performed.

wipro

whenever the time constraint is important ...real time
systems come into view. These systems are intended to be
made for alone big project usually like rocket launching.

microprocessor:
1 general purpose digital computer
2 many operational codes for moving data from external 
memory to cpu
3 rapid movement of code and data from externel address to 
chip

microcontroller
1 specific purpose digital computer
2 one or two codes for moving data from external memory to 
cpu
3 rapid movements of bits within the chip

Microprocessor:-1.The ability to execute a stored set of 
instructions to carry out user defined tasks. 
                2.The ability to be able to access external 
memory chips to both read and write data from and to the 
memory. 

Microcontroller:-A microcontroller is a device which 
integrates a number of the components of a microprocessor 
system onto a single microchip. 

So a microcontroller combines onto the same microchip :