That's a construction that's left over from B. The number on the left is a PDP-11 address, probably for some kind of control register.

In B, all data was stored in the same sized bucket. For arrays, the bucket contained the address of the beginning of the storage allocated for the array. For data, the bucket contained the data. On a byte-addressed machine, Dennis had to do some real magic to load and execute these programs (e.g., shift addresses right by a bit). And, of course, because there were no types, there was no type checking, and thus no way to disambiguate structure members, so all names of structure members had to be unique. If one structure had a member "next", no other structure could have a member "next". (actually, it could if they were at the same offset in the two structures, but that was pretty dangerous...). And early C (originally called nb, "new B") had to be able to run most B programs by just adding some declarations...

I can't help you with nm, but it might not tell you much if you had it...

Steve

----- Original Message -----
From:
"Diomidis Spinellis" <dds@aueb.gr>

To:
"TUHS main list" <tuhs@minnie.tuhs.org>
Cc:

Sent:
Mon, 19 Dec 2016 21:47:28 +0200
Subject:
[TUHS] nm on Third Edition .o files?

. . .

However, I stumbled on the use of structure fields on things that aren't
structures, e.g. "0177776->int =| 300"