hi i am new to electronics and i have just decided to make a dotmatrix pong game 7x8 matrix (pog game is just two paddles and a ball that you batt around until someone misses) and someone said to use a 74LS138 3-to-8 decoder i am not sue on what these are and how the work ive looked around on the net and all i get is mostly junk can someone please help and tell me please thanks