Unsigned intger, sign magnitude notation (Binary)

Hey guys, I've searched and searched but I can't seem to find any help on this question I have.

Express the following bit pattern 10011001 in:

a) Unsigned integer

b) Signed integer in sign-magnitude notation

c) Signed integer in Twos-compliment

I don't understand what these means and I've looked online but I can only find converters etc but I need to learn how do do this with pen and pad for my exams. Please try to explain the best you can if you can. Thanks.

Re: Unsigned intger, sign magnitude notation (Binary)

OK I can do a and b. In binary there is no + or - so all numbers are unsigned integers unless otherwise specified, therefore converting the binary no to a decimal will give a). We know computers deal with signed integers too, in this case the first digit in binary assigns + or - to the figure (not sure which is which), so the signed int will be -/+ from the first digit and the decimal will be the representation of the rest of the digits.. not sure about c.

I suggest googling for how computers use numbers for this rather than just binary

Re: Unsigned intger, sign magnitude notation (Binary)

Can anyone else shed some light?

Re: Unsigned intger, sign magnitude notation (Binary)

"twos complement" has negative numbers with "1" as first bit and the magnitude given as the complement of each bit:

the number +1011011 would be stored as 01011011 while -1011011 would be stored as 10100100.