[TUHS] Emacs and undump

[tfb@tfeb.org (tfb@tfeb.org)]

On 27 Feb 2017, at 07:19, Lars Brinkhoff <lars at nocrew.org> wrote:
> 
> Emacs came from ITS, and many Lisps derive from Maclisp which also came
> from ITS.  In ITS, it was common for applications to be dumped into a
> loadable core image, even if they were written in assembly language.

I think the history of this must go back beyond ITS.  InterLisp did the same thing, and it's a west-coast Lisp so probably not influenced by ITS (and it probably predates ITS in its beginnings).  So either the idea was just pervasive (which is at least plausible I think) or it has its roots somewhere further back: I wonder what Lisp 1.5 did?

Oddly I once learned something important about TCP because of this.  I had a Xerox D-machine (an 1186, which was a Daybreak I think), which I needed to move somewhere.  I was logged into it and running a Lisp image with lots of state, so I did whatever incantation was needed to write all the dirty pages to disk halt Lisp, turned the machine off and carried it wherever it needed to go, plugged power and network back in and restarted the image.  Unbeknownst to me I had a couple of telnet windows open to Unix machines: when I turned the machine back on they were not only still open but they still had live sessions in them.

Well, it seems obvious now, but that was the moment when I understood how TCP worked.

--tim