well though you cannot guess at the internal ckt by just looking at it, there are a whole lot of books and websites out there that will give you just what you need.
like nigel pointed out, the first thing to do is to check the number of the chip, for instance OP07C is an op-amp.
once you do that, you cann look up www.vishay.com or www.datasheetlocator.com
if your chip is from texas instruments, you can go straight to their home page and search for your component there!
datasheetlocator is pretty extensive, if you know your manufacturer, things are all the more simple!