Abandonware does not, in any LEGAL sense, exist. It's a made up concept for gamers to feel better about themselves when they pirate. Hey! The game's been ABANDONED! It doesn't count, right??
Well, legally, yes it does.
Practically, maybe it doesn't, though. If the entity that holds the copyright on the game chooses not to enforce its rights, then as a PRACTICAL matter, you're safe in pirating it. Legally, it's still just pirating, though.
Unless the game has gone into the public domain (and to my knowledge, it hasn't), it's still illegal to download without paying.