4 Nov
2024
4 Nov
'24
7:29 a.m.
On Nov 4, 2024, at 12:34 AM, ben via cctalk
<cctalk(a)classiccmp.org> wrote:
On 2024-11-03 9:37 p.m., Tony Duell via cctalk wrote:
Yes, and they are documented in the PDP-11 architecture manual, in an appendix. But it
cases that are machine dependent are more exotic, things like mixing a register reference
with an auto inc/dec of the same register. The magic move will work on any of them.
On the "one word clear", I missed a detail. I pointed out you get to initialize
the registers. You can also initiate one memory word. In other words: choose two words
in memory, and registers contents, such that execution will give you a memory full of
zeroes and a halted machine.
paul
On Mon, Nov 4, 2024 at 4:06 AM Mychaela Falconia
via cctalk
<cctalk(a)classiccmp.org> wrote:
Where there any user instructions between models that gave strange behavior on the wrong
machine?
Paul Koning wrote:
Does that work on all models of PDP11?
I had an idea that (as in C) the order of the decrements and reads was
not specified by the instruction set definition and that on some
machines (the 11/45?) it doubly decrements PC before reading or
storing.
-tony 1. Show a one-word PDP-11 program that writes all
of memory, in reverse order.
MOV -(PC),-(PC)