Newsgroups: vmsnet.pdp-11
Subject: Re: UNIX for 18-bit pdp-11:s...
From: Chris Petrilli <petrilli@gnu.ai.mit.edu>
Date: Sun, 13 Sep 92 13:11:31 -0600
Organization: The Internet
Return-Path: <pat+@transarc.com>
CC: info-pdp11@transarc.com


>>>>> On Sun, 13 Sep 92 01:22:22 -0700, sms@WLV.IIPO.GTEGSC.COM (Steven M. Schultz) said:

Steven> Sounds like a "high-end" pdp-11 is anything that _excludes_
Steven> split I/D and supervisor mode.  Guess that leave the 11/44,
Steven> 11/53, 11/73, 11/83 out.  11/44s are _dirt_ cheap these days
Steven> and run Unix just fine.  11/84s are also "cheap" (but cheap !=
Steven> free).  Heck, even the 11/45 (ca. 1975) had those
Steven> capabilities.  Only the "low end" models left them out.

Right, that would be the basic break down on PDP-11 machines.  The
``low end'' models were excrutiatingly slow.  Unix, even in its early
days was not a small system, and a system, such as the normal 11/23
with it's memory limitations is not going to be able to cut it.

Steven> A 70 is a "labor of love" these days - it was the last of the
Steven> "real computer" since it had a front panel mit lights and
Steven> switches. Gads i miss having a 70 but the house wiring and my
Steven> budget can't stand one.  Super machine when it was working
Steven> right, but heaven help you if anything ever went wrong with
Steven> one.

My last PDP-11 was a 11/70, fully loaded with MASSBUS toys and was a
fun thing to play with, but gods save my electric bill :-)  I have an
11/785 right now that uses less power, though for the time being it
stays in storage until I can give it a decent ``environment'' to work
in.

Steven> Depends on what a person plans to do.  RSX and RSTS were hand
Steven> crafted in assembly to do their jobs well, and they do it very
Steven> well indeed.  I used to work with RSX/IAS (in MACRO-11 of
Steven> course) and i don't miss at all the UPPERCASEFILENAMES and 6+3
Steven> character file names, lack of IP/TCP networking, effort to
Steven> OPEN$ a file (gads, setting up a FDB was a chore), etc.

Agreed, but unless you really NEED the facilities of Unix, then it's
probably a better choice.  as for TCP networking, that is something
that is going to be a BIG problem in the upcoming years, as Internet
moves away from IP4 (what most people call TCP/IP) to a new protocol
(I *HOPE* Pip, since I'm working on that).  Honestly, I don't think
the PDP line is going to have the CPU cycles to handle the new
protocols, since they place a slightly higher load on the host, and
simplify the router's job (for various reasons).

Steven> How recently?  Tried 2.11BSD at all?  It might be a bit
Steven> different than earlier experiences with Unix on a pdp-11.  I
Steven> know V7 was a real PITA (especially on a 11/23 - had enough
Steven> room left over after the kernel to run 1 or 2 user processes,
Steven> the system spent most of its time swapping).

Yes, I have a version of 2.11BSD here, in adition to 2.6 and 2.9.
While it is an enormous step forward, it still isn't what a lot of
people might expect.

Steven> It's spoiled almost everyone except the really hardcore folks
Steven> who know that "good computing" (like good cooking) takes time
Steven> ;-)

As at least one person on here can attest to, I'm far from a ``cushy''
hardware person, and the ammount of ``old junk'' (as others refer to
it) that I own can attest to that :-)

Steven> Why bring up a superdooper workstation and then confess to a
Steven> fondness for old machines?  I'm tempted to wager that a goodly
Steven> percentage of the 50mips is doing nothing more than driving
Steven> the glitzy displays...  Over the years i've noticed machines
Steven> getting faster, the screens more colourful and glitzy, but not
Steven> a whole lot more work getting done.

I agree, I don't think the amount of work has kept pace with the speed
increases, though I can do things today on the machines I use that I
could never do on a PDP, and certainly I wouldn't be able to do
software developemnt nearly as fast.  But that isn't the issue, I
brought it up because I think people need to understand what they are
getting into when they are looking at a PDP running Unix.

Steven> One does not buy (or accept for free) a pdp-11 because of it's
Steven> blinding speed (although the 11/93 introduced in 1990 is quite
Steven> fast for an 11).  Speed comparisons between almost anything
Steven> against a 11/44 or 11/73 would show the 11 as a slower
Steven> machine.  So what?  I kinda like taking a watercloset break
Steven> once in a while ;-)


Buy a PDP?  I haven't paid for one yet :-)  Well, I can usually take a
break while i'm waiting for Emacs to load *laugh* :-)

Steven> I have to disagree somewhat.  V7 and descendants were never PD
Steven> in the first place (the DEATHSTAR you know). Unix for the
Steven> pdp-11 will never be PD (or easily affordable) given USL's
Steven> current attitude, etc.  Current PD code takes at least a "high
Steven> end" pdp-11 to even attempt a port (and forget anything that
Steven> comes out of the GNU project - it typically takes more memory
Steven> than you can put on a 11).

No, I mean PD code, not the OS itself, though being a kernel hacker,
it would be nice to be able to play with the kernel.  As for GNU
software, since I'm part of hte project, I should defend it, but i
won't since I bitch as much as anyone about the bloated nature.
However, much of that is NOT do to our work, but the fact that things
in general are getting bloated.  When a simple ``hello world'' program
is compiled and takes 77K (the code is about a page), you can't blame
the programmer that wrote the program, it lies squarely on the
shoulders of the people that wrote the OS.

Steven> Agreed, the earlier compilers (the DECUS C compiler is based on
Steven> a ~V7'ish version) were rather poor, but that reflects the era
Steven> rather than the machine/system.  Again, noone's done much - they're
Steven> all "spoiled" and can't be bothered with less than ~50 mips machines.

Well, that's far from the truth.  I use everything from Sun-3s ('bout
3-4 MIPS) to Convex C3480 mini-supercomputers, and I keep coming back
to whatever machine lets me get the work done easiest (usually a
NeXT).  The problem is  that many people dont' have the TIME to spend
on a new compiler.

Steven> Can't discourage me - i'm a hardcore 11'er :-) What they'd be
Steven> getting into is some serious $$$ though, pdp-11 peripherals
Steven> are not in the "PC" price range - it takes a certain
Steven> "obsession" level to have a pdp-11 these days.

Obsession is a good word :-) Right Scott? :-)

And yes, peripherals are outrageous.  An 80Mb HD shouldn't cost
several thousand dollars :-)

Chris