[TUHS] history of virtual address space

[Warner Losh via TUHS]

On Tue, Jan 20, 2026, 9:49 AM Rich Salz <rich.salz at gmail.com> wrote:

>
>
> On Mon, Jan 19, 2026 at 7:05 PM Warner Losh via TUHS <tuhs at tuhs.org>
> wrote:
>
>> 4.2BSD on the Vax dereferencing 0 would seg fault. I'm not sure when this
>> started. I am sure that System V or 32V on the Vax dereferencing 0 gave
>> 0.
>
>
> Are you sure?  My memory is the opposite.  For example,
> https://www.tuhs.org/Usenet/comp.bugs.4bsd/1989-July/003016.html
>


Maybe it was a local hack. I know for sure that the vax assembler i wrote
definitely core dump when i did *NULL... it may have been 4.3 by then... I
also recall a prof or TA saying that 4.1BSD burned a lot of time on
infinite loops that students wrote, but now they are core dumps... But I've
not looked at the 4.3 sources to see if that's unmapped.

Warner

>
>