How to get a read-only prompt in emacs shell

[vnsingh]

Hi,

I extensively invoke a Unix shell within emacs to execute any Unix commands
or run a script.
But I notice when I press backspace the prompt also gets edited or if enter
C-a which I expect 
to get to beginning of cmd, it goes to beginning of prompt.
Is there any way emacs can know the prompt is read-only and that it is a
prompt.
That is, can it behave like a shell where the prompt is a prompt and not
just some text.

Could you please help me on how to do this.
I am a novice user of emacs and I have beginning to love it.

Three cheers to your work. 

- Thanks,
  Vish