[TUHS] Work I've done with a PDP-11 simulator

SPC spedraja at gmail.com
Tue May 13 03:20:48 AEST 2014

Mmm... clearly a marginal case (derive it to another thread if you consider
it opportune), but... I got one PDP-11/23-PLUS without any kind of disk (by
now, I got one RL12 board plus one RL02 drive pending of cleaning and
arrangement)... I guess if could be possible to run V6 in this machine.
There's any kind of adaptation of this Unix version (or whatever) to run
under ?

Kind regards

Saludos | Greetings | Freundliche Grüße | Salutations
*Sergio Pedraja*
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No crea todo lo que ve, ni crea que está viéndolo todo

2014-05-12 19:06 GMT+02:00 Noel Chiappa <jnc at mercury.lcs.mit.edu>:

>     > From: John Cowan <cowan at mercury.ccil.org>
>     > Well, provided the compiler is honest, contra [Ken].
> A thought on this:
> The C compiler actually produces assembler, which can be (fairly easily)
> visually audited; yes, yes, I know about disassembly, but trust me, having
> done some recently (the RL bootstrap(s)), disassembled code is a lot harder
> to grok!
> So, really, to find the Thompson hack, we'd have to edit the binaries of
> the
> assembler!
> For real grins, we could write a program to convert .s format assembler to
> .mac syntax, run the results through Macro-11, and link it with the other
> linker... :-)
> Also, I found on what's going on here:
>     > What was wierd was that in the new one, the routine csv is one word
>     > shorter (and so is csv.o). So now I don't understand what made them
> the
>     > same sizes!? The new ones should have been one word shorter!? Still
>     > poking into this...
> The C compiler is linked with the -n flag, which produces pure code. What
> the linker documentation doesn't say (and I never realized this 'back in
> the
> day') is that when this option is used, it rounds up the size of the text
> segment to the nearest click (0100).
> So, in c2 (which is what I was looking at), the last instruction is at
> 015446, _etext is at 015450, but if you look at the executable header, it
> lists a text size of 015500 - i.e. 030 more bytes. And indeed there are 014
> words of '0' in the executable file before the data starts.
> And if you link c2 _without_ the -n flag, it shows 015450 in the header as
> the text size.
> So that's why the two versions of all the C compiler phases were the same
> size (as files); it rounded up to the same place in both, hiding the
> one-word
> difference in text size.
>         Noel
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