Can I use Chocolate Chips in place of Semi-sweet baking chocolate?
Yes, you can use the choco. chips.  One square of chocolate is normally one ounce.  Half a cup of chocolate chips is usually around three ounces.  If you are looking to use 8 squares (8 ounces), you will need about 1 and a quarter cups of the chips (maybe just a tad more).
Some folks may come on and say that the chips are sweeter, less intense in flavour, etc., but when you are in  a pinch, you can sub them out just fine.  Doubtful you will notice any difference.