Computer System questions

1-What is the largest and smallest positive values in an 8 bit register given that 2¡¯s complement system is used? 2-What is the largest and smallest negative values in an 8 bit register given that 2¡¯s complement system is used? 3-Write the truth table for the case where we have 3 inputs and the output is 1 when two or more of the inputs are 1.