In article ,
Robert Chambers wrote:

I bet you one of those AI's is suction driven. That's all you'd have in
the event of an electrical failure.

Nope; both primary AI's are painted on CRT screens anyway, and they're
powered by 115VAC, as I mentioned in an earlier post.

Electrical failure is covered by a third electric AI, which has an
independent rechargeable battery backup good for at least 30 minutes.