Subject: "Structure of OS" Course and Real Life

From: Shlomi Fish <[email-masked]>
Date: Wed, 14 Nov 2001 21:03:37 +0200 (IST)

After I studied the EE "Structure of OS" course, it is my opinion that it
was one of Computer Science-related courses that is most relevant to day
to day life. The reason is that the tasks faced by an operating system are
very similar to a task a human being or an organization faces too.

As a small example let's take the common paradigm that says that if I have
a lot of homework to do, I'll start with the easiest ones first. This is a
variation of the Shortest-Job First (SJF) algorithm in process scheduling.

I'm not saying I'm going to implement any of the algorithms or
methodologies I learned there out of the book, but they do give a lot of
insight and intuition. And that's a good thing.<tm>

Do you share my opinion (or oppose it), or can relate a real-life story in
which your knowledge of OS Structure helped you in real-life?

Regards,

	Shlomi Fish

----------------------------------------------------------------------
Shlomi Fish        [email-masked]
Home Page:         http://t2.technion.ac.il/~shlomif/
Home E-mail:       [email-masked]

If:
1. A is A
2. A is not not-A
does it imply that
1. B is B
2. B is not not-B

---

From: "Nadav Har'El" <[email-masked]>
Date: Thu, 15 Nov 2001 00:27:41 +0200

On Wed, Nov 14, 2001, Shlomi Fish wrote about "[hackers-il] "Structure of OS" Course and Real Life":
>..
>..

:)

Ok, let's see: (it's a joke, and parts require some Linux inside information,
so don't take it too seriously!)

1. Virtual memory and paging:
   I have much more books than I can put on my night-stand. Books that are
   on my night-stand are quickly accessible (when I'm in bed, that is), and
   books on the shelf are not (I hate getting up from the cozy, warm, bed).
   So, when I suddenly feel like reading a book that is not on the night-
   stand, I have no choice but to go to sleep. In the morning, I wake up and
   always find the book I wanted next to the bed! As it turns out, when I was
   asleep, another process, known as "sleepwalkd" got me the book I wanted.
   Also, when my nightstand already has too many books on it, The sleepwalk
   process moves one of the books - the one I'm least likely to want to read
   next - back to the shelf.

   Last month, four Europeans with weird names decided to mess around with my
   book-reading system. One called Alan decided that in some cases I should
   move *all* my books to the shelf, go to bed without any books the same
   night, and instead fill the nightstand with crap. And if somehow all my
   shelves are full I should just burn one at random (if it burns the whole
   shelf, or the wrong shelf, who cares).
   Another one, called Andrea, decided that I should redesign my whole
   sleepwalking routine according to his master-plan. However, this made my
   sleepwalking become so strange, that people were hesitant to call me
   "stable" any more. Alan thought my new sleepwalking was a sure sign of
   be not being stable.
   But then a third European, Linus, finally made a judgment-call, and decided
   that I was stable, even with Andrea's new sleepwalking routine. He then
   told yet another European, Marcello, that from now he's resposible for
   keeping me stable. I thought it was my shrink's resposibility, but
   Marcello said no, that now that he finally has some responsibility he's not
   going to just give it up.

2. Journaling filesystems:
   Imagine writing stuff on a lot of different notes and pieces of papers,
   etc., and then suddenly getting hit in the head and forgetting everything
   (call this rebooting). You suddenly don't know which was the note you
   were in the middle of writing, and you may end up finding a note saying
   "kill <name>" not knowing you really meant to write "kill <name>'s jobs on
   the department's workstation, because they are hogging all resources" before
   you got hit on the head. That's why you should have a journal. Write
   everything that you do in there, one entry after another, and only when
   you complete a whole note, cut it out of the journal and keep it.

   Also, when you go to the bathroom, don't forget to write down in the
   journal about whether you're already done with #1, #2, or #3 (don't ask
   what #3 is...). That way, if you suddenly get hit on the head (say, the
   nice fake plant over the toilet falls on you) you won't get embaraced,
   asking yourself questions like "Oops, I don't remember if I did #2 or not,
   so should I reach for some toilet paper or not?" If you had a journal,
   everything would have been much simpler. Just look in there, and see what
   you've been up to.

3. Blue Screen of Death:
   Some people, after a bit of strenuous activity, or simply a couple of
   days of normal life, suddenly go blue and freeze up. Some people call it
   the blues, others just call it death, but in OS lingo it's simply the
   Blue Screen of Death. When that happens to a you, somebody passing by then
   needs to hit you on the head (this is called a "reboot", after the footwear
   usually worn while kicking someone's head). After a minute, you wake up,
   forgetting everything you didn't write down before the event, but
   functioning much better than you did before (at least for the first hour).

4. User Friendliness and Graphical User Interface:
   Most people are not very user-friendly. Try talking to a person (especially
   of the opposite sex) and trying to guess what you're supposed to do now,
   what the other person wants from you, what would happen if you did this,
   and what would happen if you did that, and how the heck to you get the
   other person to do what you really want. No more of that! People should
   get a graphical user interface. Why talk to the other person in that
   complex command line language we call "Hebrew", when you can just look at
   the menu, see the options "Leave me alone" and "Let's have sex" and just
   chose the one you want! Better yet, why not have a toolbar, with nice little
   icons?

5. Authentication:
   In the simple old days, to recognize someone you'd just look at his face
   and try to remember who it is (if you didn't forget it in one of the Blue
   Screen of Death episodes). But there's a much better way, which is more
   mathematically-sound: RSA! Why try to remember a (many times ugly) face,
   when instead you can remember a person's 1024 bit RSA key? (remembering
   1024 ones and zeros is a lot of fun! try it!) Then, when you meet the
   other person, and you want to be sure it is *really* that guy, not some
   Hannibal Lektor who pealed his face off and wore it, all you need to do is
   to make up a random number (try not to choose 7, because that is too easily
   guessable!), do some fun arithmetic with 1024 digit numbers, and then tell
   the other person the result (hoping that the other guy doesn't get bored
   by you reading out aloud the digits "one" and "zero" a thousand times) and
   ask him to try to guess the random number from it. If he succeeds, he's
   not Hannibal Lektor - but he's probably mad anyway.

-- 
Nadav Har'El                        |  Wednesday, Nov 14 2001, 29 Heshvan 5762
[email-masked]             |-----------------------------------------
Phone: +972-53-245868, ICQ 13349191 |Attention: There will be a rain dance
http://nadav.harel.org.il           |Friday night, weather permitting.

---

From: "Orna Shemesh" <[email-masked]>
Date: Thu, 15 Nov 2001 08:26:21 +0200

i usually do paging when i have a lot on my mind: i take a peace of paper,
and write every task which needs to be done on it. then i can go on and
process whatever it is i am currently doing, with enough memory space.

if i do not wear my glasses, my cpu must work harder on the image processing
and i get a headache. hence, i use the video card in my glasses to allow
more cpu for other processes.

Orna.

---

From: Oleg Goldshmidt <[email-masked]>
Date: 15 Nov 2001 10:28:49 +0200

"Nadav Har'El" <[email-masked]> writes:

> Ok, let's see: (it's a joke, and parts require some Linux inside
> information, so don't take it too seriously!)

We won't, but thanks - I enjoyed it ;-)

>    told yet another European, Marcello, 

Marcelo Tosatti, I presume. Does sound Italian, but IIRC he works for
Connectiva in Brasil. Is he European?

-- 
Oleg Goldshmidt | [email-masked] 
"If it ain't broken, it has not got enough features yet."

---

From: "Nadav Har'El" <[email-masked]>
Date: Thu, 15 Nov 2001 11:32:37 +0200

> Connectiva in Brasil. Is he European?

I'm not sure - I admit my fact-checking for that rediculous "piece" was a
little weak ;) Anyway, I assumed that just as Linus came from Finland and
is now working in the states, so does Marcelo come from Italy and now works
in Brazil (or just *for* Brazil, like Alan lives in the UK and works for
Redhat). I have no idea. Sorry about the somewhat racist attitude of assuming
all of them are European - I was just refering to the curious fact that the
most important Linux developers aren't American - contrary to the common belief
that all innovation comes from the US.

-- 
Nadav Har'El                        |   Thursday, Nov 15 2001, 29 Heshvan 5762
[email-masked]             |-----------------------------------------
Phone: +972-53-245868, ICQ 13349191 |If Barbie is so popular, why do you have
http://nadav.harel.org.il           |to buy her friends?

---

From: Adi Stav <[email-masked]>
Date: Thu, 15 Nov 2001 14:58:59 +0200

> that all innovation comes from the US.

Indeed. I think Al Viro is the only American citizen among the very
fuzzily defined "core group". Also consider the Dutch (Connectiva) 
Rik van Riel, and UK-born Aussie Keith Owens.

---

From: Oleg Goldshmidt <[email-masked]>
Date: 15 Nov 2001 12:06:15 +0200

"Nadav Har'El" <[email-masked]> writes:

> I was just refering to the curious fact that the most important
> Linux developers aren't American - contrary to the common belief

That was my hidden reason for nitpicking the way I did. I just decided
not to say it directly. The first PC (no, not the Altair), the first
consumer computer communication network (MiniTel), the Web, Linux and
so much other innovation - all coming from Europe and becoming
successful commerce thanks to the Americans. I find it curious...

---

From: "Nadav Har'El" <[email-masked]>
Date: Thu, 15 Nov 2001 15:51:44 +0200

> > > Connectiva in Brasil. Is he European?

http://linuxpr.com/releases/4305.html says Marcelo is Brazilian, with no
mention of him being Italian. Sorry for the mixup...

Another interesting point is that this guy is (only) 18 years old. Interesting.
Of course, if he was an Israeli, in this age he would have been drafted to the
army, and he would never have had this chance...

-- 
Nadav Har'El                        |   Thursday, Nov 15 2001, 29 Heshvan 5762
[email-masked]             |-----------------------------------------
Phone: +972-53-245868, ICQ 13349191 |The message above is just this
http://nadav.harel.org.il           |signature's way of propagating itself.

---

From: Dan Kenigsberg <[email-masked]>
Date: Thu, 15 Nov 2001 16:31:13 +0200 (IST)

>    I have much more books than I can put on my night-stand. Books that are

Attention, Nadav! You are straying from essays into fiction, and maybe even
poetry! 

Anyway, reading this one was time consuming, but rewarding..

Dan.

---

From: "Nadav Har'El" <[email-masked]>
Date: Thu, 15 Nov 2001 16:54:41 +0200

On Thu, Nov 15, 2001, [censored] wrote about "Re: [hackers-il] "Structure of OS" Course and Real Life":
> [censored]

:)

I see that some of you like this sort of computer fiction :) Here's another
one I wrote in 1998 (in private correspondence), and answers the all-important
question: "Where do deleted characters go?", as well as how Microsoft and
the ISO-8859-8 encoding *really* got started :)

From: "Nadav Har'El" <nyh>
Subject: the sad story of characters
Date: Mon, 12 Oct 1998 00:48:47 +0200 (IST)

> QUESTION: Where do delected characters go?

I think that characters are simply recycled! The byte holding the character
ceases to be a character, becoming 8 bits which can be used to make another
character, when one is needed :)

Crashing a computer is not moral - what it really does is to throw all
homeless characters, wandering the RAM streets of your computer, into the
recycling bin. In contrast, characters that have secured themselves a nice
cozy home in the luxurious neighborhood called "the hard-disk", or that have
taken the train (named "the network") away from your computer before the
catastrophe, are saved :)
Millions of homeless characters are recycled in this way in each second
throughout the world, and most people don't do anything to stop it!

   #    ######   #####  ######  ####### #######  #####  #     #   ###         #
  # #   #     # #     # #     # #       #       #     # #     #    #          #
 #   #  #     # #       #     # #       #       #       #     #    #          #
#     # ######  #       #     # #####   #####   #  #### #######    #          #
####### #     # #       #     # #       #       #     # #     #    #    #     #
#     # #     # #     # #     # #       #       #     # #     #    #    #     #
#     # ######   #####  ######  ####### #        #####  #     #   ###    #####

However, characters are doing their best to save themselves and their
relatives from the terrible fate of recycling. The dwindling population of
backslashes ("\"'s) which were not needed by anybody, caused the backslashes
and the members of the "save the backslash foundation" to hold an emergency
meeting in 1980. The operative decision was to create an operating system
where backslashes hold a key role, which would prevent them from ever becoming
extinct. To head this operation, they selected Bill Gates, a well-known
backslash supporter. Gates and other members of the "save the backslash
foundation" (later renamed "Microsoft", a much more catchy title) wrote an
operating system called MS-DOS, which was trash but kept a key role for
backslashes in its file's pathnames. The "save the backslash" operation
was a smashing success, saving the backslashes from the fate of extinction
and making Gates the richest man in the world.
Unfortunately the population slashes ("/"'s), has decreased as the population
of their sworn enemies, the backslashes, increased. However, large
communities slashes still exist on many islands throughout the world known
as "UNIX computers", where they still hold the key positions given by
Gate's supporters to their enemies, the backslashes.

Another story of mass character extinction that was averted, is the story
of characters named (in octal, as most characters like to be named) 340-372.
This tribe of characters was fast becoming extinct. Nobody wanted to use them.
Trying to repeat the success of the "save the backslash" operation failed,
because nobody wanted to use these ugly, hard to remember, characters.
Most computer manufacturers didn't even bother to show the pictures of these
characters on the displays, or used ugly and unimaginative combination of
letters and accents for them. Some bigots even said that "all these
characters look alike". The only thing saving these characters from the fate
of extinction was their sporadic appearances in binary files. It seemed that
even though nobody wanted those characters in their file, they still needed
them for the dirty jobs in executable files - such as a "increase accumulator
by 7 and then divide by 4" machine instruction, that no other character
wanted to do.
However, in the last decade the population of the 340-372 tribe has increased.
Rumors started arriving that a tiny country in the Middle-East, called Israel,
was a heaven for the 340-372 characters. The rumors said that such characters
were hired all the time, and ruler over the other characters. They said that
the characters of the tribe were referred to in Israel as "Hebrew characters",
or characters of the holy language. Characters hearing the rumors soon started
crossing oceans and arriving into Israel by whatever means they found. Some
took an airplane, using "diskette class" or "CD-ROM class", for lack of money
to buy even an economy-class ticket. Others took the dangerous, but even
cheaper, way of the network train, which took a high death toll (many packets
full of characters were reported missing and never made it through the journey.
other characters arrived disfigured by errors). But fortunately, most of the
340-372 population has succeeded in immigrating to Israel, where they
prospered.

#    #  #       #     # #     # ####### ######   #####  ######   #####  #######
#   #   #       ##   ## ##    # #     # #     # #     # #     # #     #    #
#  #    #       # # # # # #   # #     # #     # #     # #     # #          #
###     #       #  #  # #  #  # #     # ######  #     # ######   #####     #
#  #    #       #     # #   # # #     # #       #   # # #   #         #    #
#   #   #       #     # #    ## #     # #       #    #  #    #  #     #    #
#    #  ####### #     # #     # ####### #        #### # #     #  #####     #

-- 
Nadav Har'El                        |   Thursday, Nov 15 2001, 29 Heshvan 5762
[email-masked]             |-----------------------------------------
Phone: +972-53-245868, ICQ 13349191 |Computers are like air conditioners. Both
http://nadav.harel.org.il           |stop working if you open windows.

---

From: Omer Zak <[email-masked]>
Date: Thu, 15 Nov 2001 17:48:06 +0200 (IST)

> Anyway, reading this one was time consuming, but rewarding..

There are OS counterparts of the real life phenomenon of being infected by
viruses.  But how about food, reproduction, raising and educating
children, war, lawsuits, crime, welfare?
                                             --- Omer
There is no IGLU Cabal.  The IGLU Cabal Founders decided (foolishly) that
there must be an OS analogy to the act of funding and running the IGLU
Cabal.  Then they found no such OS analogy even after 1000 man years of
effort.
WARNING TO SPAMMERS:  see at http://www.zak.co.il/spamwarning.html

---

From: Omer Zak <[email-masked]>
Date: Thu, 15 Nov 2001 17:50:56 +0200 (IST)

> army, and he would never have had this chance...

... unless he's Arab (Linus is Swede-Finnish, the closest Scandinavian
parallel to being Arab-Israeli) or has a disability like deafness.
                                             --- Omer
There is no IGLU Cabal.  No Jewish-Saudi was found to complete the cabal.
WARNING TO SPAMMERS:  see at http://www.zak.co.il/spamwarning.html

---

From: "Nadav Har'El" <[email-masked]>
Date: Thu, 15 Nov 2001 18:04:20 +0200

> I see that some of you like this sort of computer fiction :) Here's another

Apparently, this last piece of crap^H^H^H^Hfiction also brought out some
creativity in some of those who read it :) Here's one of the interesting
replies I got (identity withheld to protect the innocent, but posted with
permission):

----------------------------------------------------------------------------
> or characters of the holy language. Characters hearing the rumors soon started

What you and the rest of the Zionist entity seem to ignore is that indeed
this tribe had proven claims for that land, and had every right for characterian
aid and refuge.
However, the range 340-372 was not totally vacant when they arrived. In fact, it
is mostly an integral part of a much larger population, including the 301-332
range too, known as "ISO-8859-6 (Arabic)" characters. Many members of the tribe
you mentioned thought that the current residents of these vast ranges could
spare a portion of it for them, but sadly, they did not. This clash of interests
and perceived justices contributed to a conflict that lasts many years.

Currently, it seems neither a sharing of the range, nor its devision solves the
problem. Some optimists hope that an international intervension (know as
Unicode) would solve it, or at least calm the aggrievences.
----------------------------------------------------------------------------

-- 
Nadav Har'El                        |   Thursday, Nov 15 2001, 29 Heshvan 5762
[email-masked]             |-----------------------------------------
Phone: +972-53-245868, ICQ 13349191 |The meek shall inherit the Earth, for
http://nadav.harel.org.il           |they are too timid to refuse it.

---

From: Eran Tromer <[email-masked]>
Date: Thu, 15 Nov 2001 18:48:26 +0200

> character, when one is needed :)
[snip]

This is a rather amusing bytewise variant of the bit bucket, "where the
last bit goes when you shift a register" [1].

Interestingly, the bit bucket story actually has a good thermodynamical
foundation: when you erase a bit the entropy of your system decreases,
so the entropy of the environment must increase. Thus, any operation
that erases a bit necessarily dissipates heat -- forgetting costs energy
[2]. This was once believed to place a bound on the amount of
computation physically possible, because the amount of energy in the
universe is finite. This turned out to be wrong, as explained below
(there are claims for other universal bounds on computation, but they
are more involved [3]).

Is forgetting really essential to efficient computation? To tackle this
we define the notion of reversible computation, in which each primitive
operation must be reversible: for every logical gate, the number of
input bits is equal to the number of output bits, and the implemented
function is a bijection from the set of inputs to the set of outputs.
Thus, for instance, you can't have an AND gate, but you can have the
gate 
  (a,b,c)->(a, b, (a AND b) XOR c)
which is just like AND except it has some spare wires which you can
ignore (but not discard). There is no information loss, so there's no
lower bound on energy dissipation, i.e., the computation can be made
arbitrarily efficient in terms of energy [4]. It has been shown that
(appropriately defined) reversible Turing machines are computationally
equivalent to deterministic Turing machines, up to a constant factor
[5]. Thus, reversible computers can do anything normal computers can,
with a bit of overhead.

So, why aren't they using reversible computation to reduce the insane
energy requirement of modern CPUs? Simply, the heat dissipation of those
CPUs is larger (by many orders of magnitude) than the lower bound
implied by their irreversibility -- they're energetically inefficient
for totally different reasons. I've seen popular press go as far as
suggesting reversible computing as a solution to California's energy
crisis, which is ludicrous.

Curiously, the quantum computation model is fully reversible (more
precisely "unitary", which is a generalization of reversibility to
superposition states). So reversible computation may yet be of much
practical interest.

  Regards,
    Eran Tromer

[1] http://www.tuxedo.org/~esr/jargon/html/entry/bit-bucket.html
[2] R. Landauer, "Irreversibility and heat generation in the computing 
    process", IBM J. Research and Development 5:183-192, 1961
[3] Seth Lloyd, "Ultimate Physical Limits to Computation", 
    Nature, 406:1047-1054, 2000
    http://xxx.lanl.gov/abs/quant-ph/9908043
    See also a new preprint:
    http://xxx.lanl.gov/abs/quant-ph/0110141
[4] C. H. Bennett, "The thermodynamics of computation -- a review",
    Intl. J. Theoretical Physics, 21:905-940, 1973
[5] C. H. Bennett, "Logical reversibility of computation", IBM J.
    Research and Development, 17:525-532, 1973

[2][4][5] can be found in this wonderful anthology:
    H. S. Leff and A. F. Rex, "Maxwell's Demon", Adam Hilger, 1990

---

From: Oleg Goldshmidt <[email-masked]>
Date: 15 Nov 2001 18:58:50 +0200

Omer Zak <[email-masked]> writes:

> viruses.  

Or bacteria, such as anthrax...

> But how about food, reproduction, 

Seems that clone() is a recent invention in this area...

> raising and educating children,

Do you mean teaching them how to use fork()?

> war, 

Race conditions? OS flame wars on the 'net?

> lawsuits, 

Mostly related to property ownership, similar to permissions...

> crime, 

cracking, intrusion, denial of service?

> welfare?

MS tech support? About as effective...

---

From: "Nadav Har'El" <[email-masked]>
Date: Thu, 15 Nov 2001 19:09:23 +0200

> Seems that clone() is a recent invention in this area...

Older releases of Emacs (I checked 20.2, I'm not sure about the current ones)
had manuals named
	celibacy.1
	condom.1
	sex.6
about these issues...

There's also a joke I saw once (I don't remember where) about a varient of
fork(), called baby(), which takes two parent processes and forks a child :)

> > war, 

Yeah, like
	kill /bin/laden

-- 
Nadav Har'El                        |     Thursday, Nov 15 2001, 1 Kislev 5762
[email-masked]             |-----------------------------------------
Phone: +972-53-245868, ICQ 13349191 |The software said it requires Windows 95
http://nadav.harel.org.il           |or better, so I installed Linux.

---

From: "Nadav Har'El" <[email-masked]>
Date: Fri, 16 Nov 2001 00:41:57 +0200

> [2]. This was once believed to place a bound on the amount of

Reminds me of some profiling I was doing on some program, and it turned out
that 10% of the runtime was doing memset()s to zero memory. I guess these
memset()s were not only CPU hogs, they also are the worst entropy decreasers
:)

> (there are claims for other universal bounds on computation, but they

According to this, "The universe can have performed no more than $10^{120}$
ops on $10^{90}$ bits.". Wow, God must have one heck of a computer lab :)

> superposition states). So reversible computation may yet be of much

Yes, if you're interested in 8 bit machines :) (and I'm not talking about
a machine with 8 bits in a byte - I'm talking about a machine with only
8 bits, and that's it)

[I hope I'm not offending any of the quantum computing researchers that I
know read this list ;) I know measuring the number of qubits is a gross
oversimplification of the quantum computer's power - I also heard the
quantum computation course, you know]

-- 
Nadav Har'El                        |       Friday, Nov 16 2001, 1 Kislev 5762
[email-masked]             |-----------------------------------------
Phone: +972-53-245868, ICQ 13349191 |Drink varnish and you'll get a lovely
http://nadav.harel.org.il           |finish.

---

From: "Nadav Har'El" <[email-masked]>
Date: Fri, 16 Nov 2001 18:55:01 +0200

> ops on $10^{90}$ bits.". Wow, God must have one heck of a computer lab :)

I tried to make a caclulation (really stupid, given the limits of our universe
and a few religious theories that contradict that article's conclusion)
on how close we are to everyone being able to play god on their own PC.

In 1982, the first personal computer I ever saw was a Commodore VIC 20. It
had 3000 bytes of memory, or roughly 10^4.4 bits. 18 years later, in 2000,
my personal computer has 128MB of memory, or roughly 10^9 bits. If we
continue in this pace (again, this suggestion is silly, but it's just thought
experiment), of adding roughly 4.5 orders of magnitude per 18 years, it will
take us only 324 years to make up the extra 81 orders of magnitude of memory
capacity (again, ignoring the limits of the universe :))

So, in 2325, everyone could potentially play god on their PC.

Why do I get the feeling that instead we'll just find a more efficient way
to kill or abuse each other?

-- 
Nadav Har'El                        |       Friday, Nov 16 2001, 2 Kislev 5762
[email-masked]             |-----------------------------------------
Phone: +972-53-245868, ICQ 13349191 |In Fortran, God is real unless declared
http://nadav.harel.org.il           |an integer.

---

From: Eran Tromer <[email-masked]>
Date: Fri, 16 Nov 2001 19:28:44 +0200

> So, in 2325, everyone could potentially play god on their PC.

Actually Lloyd means qubits rather than classical bits, so add the ~60
years from the first electronic computer to the first quantum computer.
But one nifty thing about considering the universe as a quantum computer
is that there is no decoherence due to interaction with the environment,
so maybe you can subtract a couple of years. :-)

  Regards,
    Eran Tromer

---

From: "Nadav Har'El" <[email-masked]>
Date: Sat, 17 Nov 2001 17:01:40 +0200

On Thu, Nov 15, 2001, Nadav Har'El wrote about "Re: [hackers-il] "Structure of OS" Course and Real Life":
>...

I found it - it was posted in 1991 on rec.humor.funny. You can find the
entire baby(1) fictionaly man page in

http://www.netfunny.com/rhf/jokes/91q2/babyman.html

Of course, there's also the UNIX Guru's View of Sex, in
http://www.netfunny.com/rhf/jokes/97/Nov/unixsex.html

Another gem (not all about sex) is
http://www.netfunny.com/rhf/jokes/old90/18951.html

-- 
Nadav Har'El                        |     Saturday, Nov 17 2001, 2 Kislev 5762
[email-masked]             |-----------------------------------------
Phone: +972-53-245868, ICQ 13349191 |The knowledge that you are an idiot, is
http://nadav.harel.org.il           |what distinguishes you from one.