From: utzoo!decvax!decwrl!sun!megatest!fortune!hpda!hplabs!sri-unix!gwyn@brl-vld.arpa Newsgroups: net.unix-wizards Title: Re: PDP-11 stack use Article-I.D.: sri-arpa.747 Posted: Fri Mar 4 17:10:26 1983 Received: Fri Apr 1 09:59:45 1983 From: Doug Gwyn (VLD/VMB) Fine, except there is not a "blank word" in the stack frame after the saved R2; it is part of allocated auto storage. The cell "(sp)" is available for scratch use by the C code generator and percolates to the top of the stack as it grows. The same stack frame is used on modern Bell PDP-11 UNIX, but the procedure linkage was changed from "jsr r5,csv" to "jsr r0,csav" to solve a problem discussed in this mailing list not very long ago. Bell UNIX documents the stack frame, although not as thoroughly as you have done, in the sources for csav and cret.