[comp.realtime] Speed costs

chip@tct.uucp (Chip Salzenberg) (05/25/90)

[[ Followups to comp.arch ]]

According to jca@pnet01.cts.com (John C. Archambeau):
>peter@ficc.ferranti.com (Peter da Silva) writes:
>>Did you know that C-news runs in small model?
>
>So what if C-News runs in small model.
>A vast majority of C compilers won't.

Competent C compilers can be written in small model.  I once worked on
a C compiler that ran on a PDP-11, which as everyone knows, is limited
to 64K of data under most (all?) Unix implementations.

The old saw that programs will expand to fill the memory available to
them is true.  It points out that the primary reason why mundane
programs use large memory spaces is the tendency of programmers to use
brute force to attack problems until the computer they're using runs
out of force.  It used to be that the brute force line was crossed
quite early; not so today.  Too bad.

I have in the past focussed almost exclusively on kernel bloat as the
Evil Memory Waster Of Our Time.  However, I now believe that I was
mistaken.  As much as the Unix kernel hackers have caused their baby
to grow in recent years, the utility programs and support code have
caused as much, if not more, bloat than the kernel.  There is plenty
of blame to go around.

As Henry Spencer has so often pointed out, thinking small seems to be
a lost art[*], which is a pity.  The X window system could use a small
thinker, possibly for the purpose of discarding X entirely.

[*] Were I a cynic, I might wonder if thought of any kind is in short
supply among today's programmers.  I might also cite Sturgeon's Law:
"Ninety percent of everything is crap."  However, as I am not a cynic,
I shall refrain.
-- 
Chip Salzenberg at ComDev/TCT   <chip%tct@ateng.com>, <uunet!ateng!tct!chip>

jca@pnet01.cts.com (John C. Archambeau) (05/27/90)

chip@tct.uucp (Chip Salzenberg) writes:
>[[ Followups to comp.arch ]]
>
>According to jca@pnet01.cts.com (John C. Archambeau):
>>peter@ficc.ferranti.com (Peter da Silva) writes:
>>>Did you know that C-news runs in small model?
>>
>>So what if C-News runs in small model.
>>A vast majority of C compilers won't.
>
>Competent C compilers can be written in small model.  I once worked on
>a C compiler that ran on a PDP-11, which as everyone knows, is limited
>to 64K of data under most (all?) Unix implementations.

Which brings forth the argument in favor of progress.  How many people
actually use PDP-11's anymore?  I've seen a few go in and out at garage sales.
 
     // JCA

 /*
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 ** INTERNET: jca@pnet01.cts.com            | of here!
 ** UUCP    : {nosc ucsd hplabs!hd-sdd}!crash!pnet01!jca
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greg@sce.carleton.ca (Greg Franks) (05/29/90)

In article <2832@crash.cts.com> jca@pnet01.cts.com (John C. Archambeau) writes:
>Which brings forth the argument in favor of progress.  How many people
>actually use PDP-11's anymore?  I've seen a few go in and out at garage sales.

Ontario Hydro's got nine at the Darlington NGS running the reactors.*
Maybe they replaced them with VAXes running PDP-11 emulation -
probably not though.  Back when the station was designed, chips like
the 68000 and 8088 did not even exist.  I wonder what's running the
Hubble Space telescope.  I'll bet it isn't an 88000, SPARC, 29K or
R3000.

* 256K and drum memory.  The older stations use Varian computers
(remember them?) and ancient IBM's with a whopping 32 kilowords of
store.  32 K to run a reactor - 600 K to edit its source code :-(.
-- 
Greg Franks, (613) 788-5726              |"The reason that God was able to
Systems Engineering, Carleton University,|create the world in seven days is
Ottawa, Ontario, Canada  K1S 5B6.        |that he didn't have to worry about
greg@sce.carleton.ca uunet!mitel!sce!greg|the installed base" -- Enzo Torresi

mitchh@gold.GVG.TEK.COM (Mitch Hendrickson) (05/30/90)

In article <2832@crash.cts.com> jca@pnet01.cts.com (John C. Archambeau) writes:
>Which brings forth the argument in favor of progress.  How many people
>actually use PDP-11's anymore?  I've seen a few go in and out at garage sales.

Well, we for one are still building very functional video editing
systems (basically a realtime control problem) based on PDP-11's (we
did recently start requiring memory management hardware and at least
256k, but...).  We're doing far more with them than many competitors
with "more advanced" hardware.  Works for us....

-Mitch

mcculley@alien.enet.dec.com (05/31/90)

In article <854@sce.carleton.ca>, greg@sce.carleton.ca (Greg Franks) writes...
>In article <2832@crash.cts.com> jca@pnet01.cts.com (John C. Archambeau) writes:
>>Which brings forth the argument in favor of progress.  How many people
>>actually use PDP-11's anymore?  I've seen a few go in and out at garage sales.
> 
>[...]I wonder what's running the
>Hubble Space telescope.  I'll bet it isn't an 88000, SPARC, 29K or
>R3000.
> 
That reminds me, when I first joined Digital (about 10 years ago) teaching 
RSX customer training courses, my first onsite course was taught in an IBM (!)
facility where they were working on a contract to do a ground support system
for the space telescope using an 11/70 running RSX-11M.  Seems IBM was (is?) a
DEC OEM...	:-)	:-)
(I think they produced some Unibus hardware options for interprocessor comms.)

Bruce McCulley
RSX Software Development
Digital Equipment Corp.

drd@siia.mv.com (David Dick) (05/31/90)

In <2832@crash.cts.com> jca@pnet01.cts.com (John C. Archambeau) writes:

>Which brings forth the argument in favor of progress.  How many people
>actually use PDP-11's anymore?  I've seen a few go in and out at garage sales.

There must be an enormous number of them in the field.  

DEC recently bowed to their pressure and released two new
processors based on the (J11?) chipset they've been using 
most recently.

David Dick
Software Innovations, Inc. [the Software Moving Company(sm)]