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Re: New Vax - future directions :-)

[Replying to two messages at once, here.]

>> ISTR something about keeping "an old, sourceless, Zork binary"
>> running.  [...]

> The Zork binary for 2.11BSD is a really odd hack.  It sortof
> implements part of the RT-11 environment, and uses sortof the RT-11
> binary, [...].

> o.s             Assembler driver to make dungeon run under UNIX.
> 		  [...]

>> I could add PDP-11 mode to my KA630 simulator and then add support
>> for it to NetBSD, so that if/when an FPGA version exists there'll be
>> a little more software ready for it.
> You just need some software then.


> And no, ZORK won't cut it.  It uses separate I/D space. :-)

Well, to switch messages....

>>> (Anyone talked about execute-only protection of memory... The
>>> PDP-11 [has] it. :-) )
>> Does it?  Split I/D isn't really execute-only protection in the
>> usual sense.  [...]
> Isn't that the definition of execute only? :-)

That's why I said "in the usual sense".

>> It wouldn't be hard to, for example, define a variant of PDP-11
>> compatability mode for which instruction fetches came from
>> 00010000-0001ffff while data accesses used 00000000-0000ffff.
> Unfortunately, the rules are more complicated than that.  Any
> reference through R7 (PC) goes to the I-space, even data.

Sure.  Anything that goes to I-space on a split I/D -11 gets mapped to
0001xxxx; D-space, 0000xxxx.  If you want to emulate a non-split
system, you just map the same physical pages into both ranges.

>> But running something like 2.11BSD would require more than just
>> classic VAX compatability mode, because it's more than just user
>> mode.  [...]
> Right.  Which was part of my question why bother with the PDP-11
> mode.

ZORK, of course! :)

I thought I'd seen something on a VAX system which talked about that
"old, sourceless Zork binary".  Maybe my memories are getting
conflated; that would have been decades ago by now.

If it could run under 2.11, I'm moderately sure I could make it run
under NetBSD/vax, given compatability-mode-capable hardware (or
emulated hardware).  I don't suppose you'd happen to know where I might
be able to get hold of that 2.11 binary?

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