Will its a C Compiler switch (-i) and create 411 files instead of 407.
I like to refer to it as the 17th address bit.

I was first brought out with the 11/45 (which was SSI/MSI TTL), and the
biggest differences between it and the 11/40.  They were both early 1970s
and both of these processors were multiple boards. By 1976, the 780 has
started and that sucked off most of the HW folks.   A new hire in 1976,
Jeff Mitchell supposedly had a bet with Bill Strecker that he could
implement an 11 on a single"hex high" CPU board if he got rid of the lights
and switches.  He ran out of room to implement seperate I/D, so it became
an 11/40 class [and it has an 8008-1 that runs the front panel].

The 11/70 came out between the 11/45 and the 34 and had a number of
the STAR folks on it it original but it was also multiple boards.   It was
not until 11/44 that DEC was able to make a hex height implementation of
the 11 that managed to cram a full 11/70 into that system.   The later J-11
chip set took things beyond the 11/70.

If you look at the conf directory in the sys sources for V6, you see m40.s
and m45.s - but if you look at the link line of sys/run the 45 does not
have -i; but if you look in sys/sys1.c you'll see the in the routine
getxfile the support for 0407/0411/0405/0410 files for user mode.

If you look at the conf directory in the sys sources for V7, you see mch.s
and m45.s  its common and the makefile adds -i

ᐧ

On Thu, Aug 3, 2023 at 4:35 PM Will Senn <will.senn@gmail.com> wrote:

> Does unix (v7) know about the PDP-11 45's split I/D space through
> configuration or is it convention and programmer's responsibility to
> know and manage what's actually available?
>
> Will
>
> On 8/3/23 12:00, Rich Salz wrote:
> > What, we all need something to kick now that we've beaten sendmail?
> > How about something unix, ideally a decade old?
>
>