Okay, Lets say i have two decimal values of $-102$ and $-87.$ I converted them both to hex using two's compliment representation. This yeiled me a result of $-102=9$A and $-87=$ A$9.$ Now i need to add these two numbers together. When i add them, i $1$st: Get an overflow because im adding two negative numbers as the result from the addition is $143$ which cannot be stored in an $8-$bit system. and $2$nd: I get the incorrect answer in decimal of $323$ when the correct answer should be $15.$ So my question is$,$ can somebody explain the logic to me of why adding two hex values that each represent a signed twos compliment binary value yeilds the incorrect result? also, what does the parameter of having an $8-$bit system play into this result. can someone point me in the right direction of solving this problem? Thanks!