title: How 2's complement of -128 in Bit representation for 8 bit register is 1000 0000?
body: <p>I have got a basic question for signed number representation in computer 
  Q) As i have learned in a 8-bit representation the 7th bit ( count from 0-7) is always the sign bit and the remaining 0-6 bits are the magnitude of the number </p>
  
  <p>so in case of negative number 7th bit always be 1. 
  Then how is -128 equal to 1000 0000?? </p>
  
  <p>As we see 1000 0000 this we assume its a negative number and take 000 0000 to be magnitude .. and if take the 2's complement for this it comes to be 1000 0000 </p>
  
  <p>so does in this case does the sign bit get overwritten in 8-bit register .. please explain someone .. hope i am clear at my explanation </p>