PDP-11 architecture Was: internet blocking problem ?

Noel Chiappa jnc at mercury.lcs.mit.edu
Fri Sep 11 12:36:26 CDT 2015

    > From: Johnny Billquist

    > it really is a few bits short of perfect ...
    > .. when you look at the EIS and FPP extensions, which could not
    > retain the general instruction layout format because of a lack of bits.

Well, if they'd tried to keep the same general layout, I don't think EIS,
floating point, etc would have all fit in 16 bits. Maybe they should have
made it a 18-bit machine? ;-)

But I keep circling back to the observation that the -11 architecture's
incredible flexibility/complexity ratio happened precisely _because_ it had to
be crammed into 16 bits (along with a big dollop of genius :-). Given that I
think the big challenge of the next generation of computer science is going to
be managing complexity, it's too bad we don't teach more young CS students the
-11 and UnixV6 - to show them just how much you _can_ do, with how _little_,
if you put your mind to it.

    > I still would not consider overlays as any part of the PDP-11
    > architecture. But maybe that is just me.

No, I agree with you 100%. Plenty of PDP-11 OS's did not support them.


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