Question

Given a 8 bit binary sequence 01111001, show the decimal number it represents in unsigned integer, sign-magnitude, one's complement, two's complement and execess-127.

Answer 1

since left most but is 0. No extra calculations are needed to calculate unsigned integer, sign-magnitude, one's complement, two's complement.
because in all of these representations this number is positive.
converting 01111001 to decimal
=> 0x2^7+1x2^6+1x2^5+1x2^4+1x2^3+0x2^2+0x2^1+1x2^0
=> 0x128+1x64+1x32+1x16+1x8+0x4+0x2+1x1
=> 0+64+32+16+8+0+0+1
=> 121
unsigned integer:   121
sign-magnitude:     121
one's complement:   121
two's complement:   121
excess-127 value is 121-127 = -6
excess-127: -6