How to identify old microcontrollers?
None of these are microcontrollers, they're all logic (programmable logic in the case of the GAL, fixed in the other two).  Goto sites like Digikey &amp; Mouser to enter full or partial part numbers - if there's ambiguity that a partial part number happens to match two entirely different types of components, it should be pretty clear which it is (usually).

For more generic googling, try just the first several alphanumeric characters of the part number (e.g. GAL16V8, 74LS138, 74LS74), the later characters are not usually helpful to a "just curious" search, and sometimes you need to remove the first one or two characters, but knowing when to do that is an 'acquired skill' :)