Newsgroups: vmsnet.pdp-11
Subject: Re: UNIX for 18-bit pdp-11:s...
From: <sms@wlv.iipo.gtegsc.com>
Date: Sun, 13 Sep 92 01:22:22 -0700
Organization: The Internet
Return-Path: <pat+@transarc.com>
CC: info-pdp11@transarc.com

> From: Chris Petrilli <petrilli@gnu.ai.mit.edu>
> On anything less than a high-end PDP (ie. 11/70, 11/84, etc..) I think

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

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

> RSX is a much better route.  Even RSTS would be a better choice than
> Unix.

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

> I have played with various Unix implementations on the 22bit
> machines, and while usable, I just don't think that it's going to cut

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

> it for most people.  I guess working on a 50+MIPS RS/6000 spoils me,
> but I still enjoy playing with older machines.  However, the problems

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

	*start soapbox*

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

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

	* end soapbox *

> come about in that V7 and early BSD (pre 4.2) are not well supported
> any more by PD code, much less good compilers.

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

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

> My experience with the C compiler that is on the PDP is pretty bad.

	How recent?  Granted noone's been knocking down the doors demanding
	to do a better compiler lately, but the current C compiler isn't
	all bad -- it's rather simple minded for sure, the optimizer cleans
	up after it to a great extent -- enums, structure passing, etc are
	present, seems to have all the comforts of home to me.  It's not
	ANSI though, thankfully (function prototypes are _ugly_).

> Last I recall, not only does it have quite a few bugs but it also
> generates pretty bad code.

	No bugs here.  Everything from the kernel (which is 4.3BSD ported
	over with _minimal_ changes - 'long' vs. 'int' stuff, usw.) to
	'rn', to C-Kermit5A(183) compiles just fine (but again you need a
	"high end" pdp-11 to  do it.

> I don't want to discourage anyone, just tell them what they are getting
> themselves into.

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

	Steven M. Schultz
	sms@wlv.iipo.gtegsc.com