I was thinking about the LGP-30, as used by Mel, the
Real Programmer.
Did that have indirect addressing, or was it indexed?
I'm not sure about the LGP-30, but according to the story, the RPC-4000
did have indexing.
Mel wouldn't have
used either of those new-fangled inventions, of course.
Are you sure you grok the story? The story claims that Mel used indexing.
In general, Mel would have used any available feature of the machine when
it helped him improve his program.