I have found them in a manga. It is a dialogue discussing to the third person going into a Pachinko shop.
Here is the full sentence.
What do the words やった台 and はずしてあった mean?
台 in this context is a short for パチンコ台, a Pachinko machine. やった is the past tense of やる, a verb "to play" in this context. Thus the topic of the sentense is "The Machine which Joe played". ガラス is a glass panel which is placed on the front of a machine. はずしてあった is the past ～てある form of a verb 外す, to remove. Thus the main sentence is "the front glass had been removed (at that time)". だと is a short for だと言うのか？, which is a rhetorical question "Are you saying that...?".
It's the past (or perfect) form of a verb やる. This word doesn't contain more meaning than "do" does, but compared with する, it slightly emphasizes that the action involves physical movement. According to your context, it'd mean "played" here.
That's the way we casually call machine like in "slot machine".
You can refer here for this grammatical construction. One point is: the
V + てある pattern always requires a transitive verb's active form in V's position, but V is not necessarily what the subject of the sentence has done.